Add supports of Consul Service tagged_addresses

Inherit from Consul.Agent.Service and override register() method.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,48 +0,0 @@
----
-name: Bug report
-about: Create a report to help us improve
-title: ''
-labels: ''
-assignees: ''
-
----
-
-**Describe the bug**
-A clear and concise description of what the bug is.
-
-**To Reproduce**
-Steps to reproduce the behavior:
-
-**Expected behavior**
-A clear and concise description of what you expected to happen.
-
-**Screenshots**
-If applicable, add screenshots to help explain your problem.
-
-**Environment**
-- Patroni version:
-- PostgreSQL version:
-- DCS (and its version):
-
-**Patroni configuration file**
-```
-Please copy&paste your Patroni configuration file here
-```
-
-**patronictl show-config**
-```
-Please copy&paste the output of "patronictl show-config" command here
-```
-
-**Have you checked Patroni logs?**
-Please provide a snippet of Patroni log files here
-
-**Have you checked PostgreSQL logs?**
-Please provide a snippet here
-
-**Have you tried to use GitHub issue search?**
-Maybe there is already a similar issue solved.
-
-
-**Additional context**
-Add any other context about the problem here.

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,97 @@
+name: Bug Report
+description: Create a report to help us improve
+labels:
+- bug
+body:
+- type: markdown
+  attributes:
+    value: |
+      If you have a question please post it on channel [#patroni](https://postgresteam.slack.com/archives/C9XPYG92A) in the [PostgreSQL Slack](https://pgtreats.info/slack-invite).
+      Before reporting a bug please make sure to **reproduce it with the latest Patroni version**!
+      Please fill the form below and provide as much information as possible.
+      Not doing so may result in your bug not being addressed in a timely manner.
+
+- type: textarea
+  id: problem
+  attributes:
+    label: What happened?
+  validations:
+    required: true
+
+- type: textarea
+  id: repro
+  attributes:
+    label: How can we reproduce it (as minimally and precisely as possible)?
+  validations:
+    required: true
+
+- type: textarea
+  id: expected
+  attributes:
+    label: What did you expect to happen?
+  validations:
+    required: true
+
+- type: textarea
+  id: environment
+  attributes:
+    label: Patroni/PostgreSQL/DCS version
+    value: |
+      -   Patroni version: 
+      -   PostgreSQL version: 
+      -   DCS (and its version): 
+  validations:
+    required: true
+
+- type: textarea
+  id: patroniConfig
+  attributes:
+    label: Patroni configuration file
+    description: Please copy and paste Patroni configuration file here. This will be automatically formatted into code, so no need for backticks.
+    render: yaml
+  validations:
+    required: true
+
+- type: textarea
+  id: globalConfig
+  attributes:
+    label: patronictl show-config
+    description: Please copy and paste `patronictl show-config` output here. This will be automatically formatted into code, so no need for backticks.
+    render: yaml
+  validations:
+    required: true
+
+- type: textarea
+  id: patroniLogs
+  attributes:
+    label: Patroni log files
+    description: Please copy and paste any relevant Patroni log output. This will be automatically formatted into code, so no need for backticks.
+    render: shell
+  validations:
+    required: true
+
+- type: textarea
+  id: postgresLogs
+  attributes:
+    label: PostgreSQL log files
+    description: Please copy and paste any relevant PostgreSQL log output. This will be automatically formatted into code, so no need for backticks.
+    render: shell
+  validations:
+    required: true
+
+- type: checkboxes
+  id: issueSearch
+  attributes:
+    label: Have you tried to use GitHub issue search?
+    description: Maybe there is already a similar issue solved.
+    options:
+    - label: 'Yes'
+      required: true
+  validations:
+    required: true
+
+- type: textarea
+  id: additional
+  attributes:
+    label: Anything else we need to know?
+    description: Add any other context about the problem here.

.github/ISSUE_TEMPLATE/config.yml

@@ -1 +1,5 @@
 blank_issues_enabled: false
+contact_links:
+- name: Question
+  url: https://pgtreats.info/slack-invite
+  about: "Please ask questions on channel #patroni in the PostgreSQL Slack"

.github/workflows/install_deps.py

@@ -5,7 +5,6 @@ import subprocess
 import stat
 import sys
 import tarfile
-import time
 import zipfile
 
 
@@ -20,7 +19,7 @@ def install_requirements(what):
     requirements = ['mock>=2.0.0', 'flake8', 'pytest', 'pytest-cov'] if what == 'all' else ['behave']
     requirements += ['coverage']
     # try to split tests between psycopg2 and psycopg3
-    requirements += ['psycopg[binary]'] if sys.version_info >= (3, 6, 0) and\
+    requirements += ['psycopg[binary]'] if sys.version_info >= (3, 8, 0) and\
         (sys.platform != 'darwin' or what == 'etcd3') else ['psycopg2-binary']
     for r in read('requirements.txt').split('\n'):
         r = r.strip()
@@ -46,14 +45,10 @@ def install_packages(what):
     packages['exhibitor'] = packages['zookeeper']
     packages = packages.get(what, [])
     ver = versions.get(what)
+    if float(ver) >= 15:
+        packages += ['postgresql-{0}-citus-12.1'.format(ver)]
     subprocess.call(['sudo', 'apt-get', 'update', '-y'])
-    subprocess.call(['sudo', 'apt-get', 'install', '-y', 'wget', 'ca-certificates', 'gnupg', 'expect-dev'])
-    subprocess.call(['sudo', 'sh', '-c', "wget -qO - https://www.postgresql.org/media/keys/ACCC4CF8.asc"
-                     " | gpg --dearmor > /etc/apt/trusted.gpg.d/apt.postgresql.org.gpg"])
-    subprocess.call(['sudo', 'sed', '-i', 's/pgdg main.*$/pgdg main {0}/'.format(ver),
-                     '/etc/apt/sources.list.d/pgdg.list'])
-    subprocess.call(['sudo', 'apt-get', 'update', '-y'])
-    return subprocess.call(['sudo', 'apt-get', 'install', '-y', 'postgresql-' + ver] + packages)
+    return subprocess.call(['sudo', 'apt-get', 'install', '-y', 'postgresql-' + ver, 'expect-dev'] + packages)
 
 
 def get_file(url, name):
@@ -90,8 +85,8 @@ def unzip_all(archive):
 
 
 def chmod_755(name):
-    os.chmod(name, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR |
-             stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH)
+    os.chmod(name, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR
+             | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH)
 
 
 def unpack(archive, name):
@@ -103,7 +98,7 @@ def unpack(archive, name):
 
 
 def install_etcd():
-    version = os.environ.get('ETCDVERSION', '3.3.13')
+    version = os.environ.get('ETCDVERSION', '3.4.23')
     platform = {'linux2': 'linux', 'win32': 'windows', 'cygwin': 'windows'}.get(sys.platform, sys.platform)
     dirname = 'etcd-v{0}-{1}-amd64'.format(version, platform)
     ext = 'tar.gz' if platform == 'linux' else 'zip'
@@ -115,59 +110,17 @@ def install_etcd():
 
 
 def install_postgres():
-    version = os.environ.get('PGVERSION', '14.1-1')
+    version = os.environ.get('PGVERSION', '16.1-1')
     platform = {'darwin': 'osx', 'win32': 'windows-x64', 'cygwin': 'windows-x64'}[sys.platform]
+    if platform == 'osx':
+        return subprocess.call(['brew', 'install', 'expect', 'postgresql@{0}'.format(version.split('.')[0])])
     name = 'postgresql-{0}-{1}-binaries.zip'.format(version, platform)
     get_file('http://get.enterprisedb.com/postgresql/' + name, name)
     unzip_all(name)
     bin_dir = os.path.join('pgsql', 'bin')
     for f in os.listdir(bin_dir):
         chmod_755(os.path.join(bin_dir, f))
-    subprocess.call(['pgsql/bin/postgres', '-V'])
-    return 0
-
-
-def setup_kubernetes():
-    get_file('https://storage.googleapis.com/minikube/k8sReleases/v1.7.0/localkube-linux-amd64', 'localkube')
-    chmod_755('localkube')
-
-    devnull = open(os.devnull, 'w')
-    subprocess.Popen(['sudo', 'nohup', './localkube', '--logtostderr=true', '--enable-dns=false'],
-                     stdout=devnull, stderr=devnull)
-    for _ in range(0, 120):
-        if subprocess.call(['wget', '-qO', '-', 'http://127.0.0.1:8080/'], stdout=devnull, stderr=devnull) == 0:
-            break
-        time.sleep(1)
-    else:
-        print('localkube did not start')
-        return 1
-
-    subprocess.call('sudo chmod 644 /var/lib/localkube/certs/*', shell=True)
-    print('Set up .kube/config')
-    kube = os.path.join(os.path.expanduser('~'), '.kube')
-    os.makedirs(kube)
-    with open(os.path.join(kube, 'config'), 'w') as f:
-        f.write("""apiVersion: v1
-clusters:
-- cluster:
-    certificate-authority: /var/lib/localkube/certs/ca.crt
-    server: https://127.0.0.1:8443
-  name: local
-contexts:
-- context:
-    cluster: local
-    user: myself
-  name: local
-current-context: local
-kind: Config
-preferences: {}
-users:
-- name: myself
-  user:
-    client-certificate: /var/lib/localkube/certs/apiserver.crt
-    client-key: /var/lib/localkube/certs/apiserver.key
-""")
-    return 0
+    return subprocess.call(['pgsql/bin/postgres', '-V'])
 
 
 def main():
@@ -176,8 +129,6 @@ def main():
     if what != 'all':
         if sys.platform.startswith('linux'):
             r = install_packages(what)
-            if r == 0 and what == 'kubernetes':
-                r = setup_kubernetes()
         else:
             r = install_postgres()
 

.github/workflows/mapping.py

@@ -1 +1 @@
-versions = {'etcd': '9.6', 'etcd3': '14', 'consul': '13', 'exhibitor': '12', 'raft': '11', 'kubernetes': '15'}
+versions = {'etcd': '9.6', 'etcd3': '16', 'consul': '13', 'exhibitor': '12', 'raft': '14', 'kubernetes': '15'}

.github/workflows/release.yaml

@@ -24,8 +24,11 @@ jobs:
     - name: Run tests and flake8
       run: python .github/workflows/run_tests.py
 
+    - name: Install Python packaging build frontend
+      run: python -m pip install build
+
     - name: Build a binary wheel and a source tarball
-      run: python setup.py sdist bdist_wheel
+      run: python -m build
 
     - name: Publish distribution to Test PyPI
       if: github.event_name == 'push'

.github/workflows/run_tests.py

@@ -29,20 +29,19 @@ def main():
         path = '/usr/lib/postgresql/{0}/bin:.'.format(version)
         unbuffer = ['timeout', '900', 'unbuffer']
     else:
-        path = os.path.abspath(os.path.join('pgsql', 'bin'))
         if sys.platform == 'darwin':
-            path += ':.'
-        unbuffer = []
+            version = os.environ.get('PGVERSION', '16.1-1')
+            path = '/usr/local/opt/postgresql@{0}/bin:.'.format(version.split('.')[0])
+            unbuffer = ['unbuffer']
+        else:
+            path = os.path.abspath(os.path.join('pgsql', 'bin'))
+            unbuffer = []
     env['PATH'] = path + os.pathsep + env['PATH']
     env['DCS'] = what
+    if what == 'kubernetes':
+        env['PATRONI_KUBERNETES_CONTEXT'] = 'k3d-k3s-default'
 
-    ret = subprocess.call(unbuffer + [sys.executable, '-m', 'behave'], env=env)
-
-    if ret != 0:
-        if subprocess.call('grep . features/output/*_failed/*postgres?.*', shell=True) != 0:
-            subprocess.call('grep . features/output/*/*postgres?.*', shell=True)
-        return 1
-    return 0
+    return subprocess.call(unbuffer + [sys.executable, '-m', 'behave'], env=env)
 
 
 if __name__ == '__main__':

.github/workflows/tests.yaml

@@ -5,8 +5,11 @@ on:
   push:
     branches:
     - master
-    tags:
-    - v.*
+    - 'REL_[0-9]+_[0-9]+'
+
+env:
+  CODACY_PROJECT_TOKEN: ${{ secrets.CODACY_PROJECT_TOKEN }}
+  SECRETS_AVAILABLE: ${{ secrets.CODACY_PROJECT_TOKEN != '' }}
 
 jobs:
   unit:
@@ -18,26 +21,6 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-    - name: Set up Python 2.7
-      uses: actions/setup-python@v4
-      with:
-        python-version: 2.7
-      if: matrix.os != 'windows'
-    - name: Install dependencies
-      run: python .github/workflows/install_deps.py
-      if: matrix.os != 'windows'
-    - name: Run tests and flake8
-      run: python .github/workflows/run_tests.py
-      if: matrix.os != 'windows'
-
-    - name: Set up Python 3.6
-      uses: actions/setup-python@v4
-      with:
-        python-version: 3.6
-    - name: Install dependencies
-      run: python .github/workflows/install_deps.py
-    - name: Run tests and flake8
-      run: python .github/workflows/run_tests.py
 
     - name: Set up Python 3.7
       uses: actions/setup-python@v4
@@ -75,6 +58,15 @@ jobs:
     - name: Run tests and flake8
       run: python .github/workflows/run_tests.py
 
+    - name: Set up Python 3.11
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.11
+    - name: Install dependencies
+      run: python .github/workflows/install_deps.py
+    - name: Run tests and flake8
+      run: python .github/workflows/run_tests.py
+
     - name: Combine coverage
       run: python .github/workflows/run_tests.py combine
 
@@ -92,26 +84,23 @@ jobs:
     runs-on: ${{ matrix.os }}-latest
     env:
       DCS: ${{ matrix.dcs }}
-      ETCDVERSION: 3.3.13
-      PGVERSION: 12.1-1  # for windows and macos
+      ETCDVERSION: 3.4.23
+      PGVERSION: 16.1-1  # for windows and macos
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu]
-        python-version: [2.7, 3.6, 3.9]
+        python-version: [3.7, '3.10']
         dcs: [etcd, etcd3, consul, exhibitor, kubernetes, raft]
-        exclude:
-        - dcs: kubernetes
-          python-version: 2.7
         include:
         - os: macos
-          python-version: 3.7
+          python-version: 3.8
           dcs: raft
         - os: macos
-          python-version: 3.8
+          python-version: 3.9
           dcs: etcd
         - os: macos
-          python-version: '3.10'
+          python-version: 3.11
           dcs: etcd3
 
     steps:
@@ -120,28 +109,40 @@ jobs:
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Add postgresql apt repo
-      run: sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
+    - uses: nolar/setup-k3d-k3s@v1
+      if: matrix.dcs == 'kubernetes'
+    - name: Add postgresql and citus apt repo
+      run: |
+        sudo apt-get update -y
+        sudo apt-get install -y wget ca-certificates gnupg debian-archive-keyring apt-transport-https
+        sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
+        sudo sh -c 'wget -qO - https://www.postgresql.org/media/keys/ACCC4CF8.asc | gpg --dearmor > /etc/apt/trusted.gpg.d/apt.postgresql.org.gpg'
+        sudo sh -c 'echo "deb [signed-by=/etc/apt/trusted.gpg.d/citusdata_community.gpg] https://packagecloud.io/citusdata/community/ubuntu/ $(lsb_release -cs) main" > /etc/apt/sources.list.d/citusdata_community.list'
+        sudo sh -c 'wget -qO - https://packagecloud.io/citusdata/community/gpgkey | gpg --dearmor > /etc/apt/trusted.gpg.d/citusdata_community.gpg'
       if: matrix.os == 'ubuntu'
     - name: Install dependencies
       run: python .github/workflows/install_deps.py
     - name: Run behave tests
       run: python .github/workflows/run_tests.py
-    - uses: actions/setup-python@v4
+    - name: Upload logs if behave failed
+      uses: actions/upload-artifact@v3
+      if: failure()
       with:
-        python-version: '3.10'
-    - name: Install coveralls
-      run: python -m pip install coveralls
-    - name: Upload Coverage
-      env:
-        COVERALLS_FLAG_NAME: behave-${{ matrix.os }}-${{ matrix.dcs }}-${{ matrix.python-version }}
-        COVERALLS_PARALLEL: 'true'
-        GITHUB_TOKEN: ${{ secrets.github_token }}
-      run: python -m coveralls --service=github
+        name: behave-${{ matrix.os }}-${{ matrix.dcs }}-${{ matrix.python-version }}-logs
+        path: |
+          features/output/*_failed/*postgres?.*
+          features/output/*.log
+        if-no-files-found: error
+        retention-days: 5
+    - name: Generate coverage xml report
+      run: python -m coverage xml -o cobertura.xml
+    - name: Upload coverage to Codacy
+      run: bash <(curl -Ls https://coverage.codacy.com/get.sh) report -r cobertura.xml -l Python --partial
+      if: ${{ env.SECRETS_AVAILABLE == 'true' }}
 
   coveralls-finish:
     name: Finalize coveralls.io
-    needs: [unit, behave]
+    needs: unit
     runs-on: ubuntu-latest
     steps:
     - uses: actions/setup-python@v4
@@ -149,3 +150,52 @@ jobs:
     - run: python -m coveralls --service=github --finish
       env:
         GITHUB_TOKEN: ${{ secrets.github_token }}
+
+  codacy-final:
+    name: Finalize Codacy
+    needs: behave
+    runs-on: ubuntu-latest
+    steps:
+    - run: bash <(curl -Ls https://coverage.codacy.com/get.sh) final
+      if: ${{ env.SECRETS_AVAILABLE == 'true' }}
+
+  pyright:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Set up Python 3.11
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.11
+
+    - name: Install dependencies
+      run: python -m pip install -r requirements.txt psycopg2-binary psycopg
+
+    - uses: jakebailey/pyright-action@v1
+      with:
+        version: 1.1.347
+
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Set up Python 3.11
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.11
+        cache: pip
+
+    - name: Install dependencies
+      run: pip install tox
+
+    - name: Install package dependencies
+      run: |
+        sudo apt update \
+        && sudo apt install -y \
+            latexmk texlive-latex-extra tex-gyre \
+            --no-install-recommends
+
+    - name: Generate documentation
+      run: tox -m docs

.gitignore

@@ -27,14 +27,15 @@ lib64
 pip-log.txt
 
 # Unit test / coverage reports
-.coverage
+.coverage*
 .tox
 nosetests.xml
 coverage.xml
 htmlcov
 junit.xml
-features/output
+features/output*
 dummy
+result.json
 
 # Translations
 *.mo
@@ -48,12 +49,24 @@ pgpass
 scm-source.json
 
 # Sphinx-generated documentation
+docs/_build/
 docs/build/
 docs/source/_static/
 docs/source/_templates/
+docs/modules/
+docs/pdf/
 
 # Pycharm IDE
 .idea/
 
 #VSCode IDE
 .vscode/
+
+# Virtual environment
+venv*/
+
+# Default test data directory
+data/
+
+# macOS
+**/.DS_Store

.readthedocs.yaml

@@ -0,0 +1,26 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/conf.py
+
+formats:
+  - epub
+  - pdf
+  - htmlzip
+
+python:
+  install:
+    - requirements: requirements.docs.txt
+    - requirements: requirements.txt

Dockerfile

@@ -1,6 +1,6 @@
 ## This Dockerfile is meant to aid in the building and debugging patroni whilst developing on your local machine
 ## It has all the necessary components to play/debug with a single node appliance, running etcd
-ARG PG_MAJOR=15
+ARG PG_MAJOR=16
 ARG COMPRESS=false
 ARG PGHOME=/home/postgres
 ARG PGDATA=$PGHOME/data
@@ -25,8 +25,7 @@ RUN set -ex \
             | grep -Ev '^python3-(sphinx|etcd|consul|kazoo|kubernetes)' \
             | xargs apt-get install -y vim curl less jq locales haproxy sudo \
                             python3-etcd python3-kazoo python3-pip busybox \
-                            net-tools iputils-ping --fix-missing \
-    && pip3 install dumb-init \
+                            net-tools iputils-ping dumb-init --fix-missing \
 \
     # Cleanup all locales but en_US.UTF-8
     && find /usr/share/i18n/charmaps/ -type f ! -name UTF-8.gz -delete \
@@ -43,24 +42,36 @@ RUN set -ex \
     && echo 'syntax on\nfiletype plugin indent on\nset mouse-=a\nautocmd FileType yaml setlocal ts=2 sts=2 sw=2 expandtab' > /etc/vim/vimrc.local \
 \
     # Prepare postgres/patroni/haproxy environment
-    && mkdir -p $PGHOME/.config/patroni /patroni /run/haproxy \
-    && ln -s ../../postgres0.yml $PGHOME/.config/patroni/patronictl.yaml \
+    && mkdir -p "$PGHOME/.config/patroni" /patroni /run/haproxy \
+    && ln -s ../../postgres0.yml "$PGHOME/.config/patroni/patronictl.yaml" \
     && ln -s /patronictl.py /usr/local/bin/patronictl \
     && sed -i "s|/var/lib/postgresql.*|$PGHOME:/bin/bash|" /etc/passwd \
     && chown -R postgres:postgres /var/log \
 \
     # Download etcd
-    && curl -sL https://github.com/coreos/etcd/releases/download/v${ETCDVERSION}/etcd-v${ETCDVERSION}-linux-amd64.tar.gz \
+    && curl -sL "https://github.com/coreos/etcd/releases/download/v$ETCDVERSION/etcd-v$ETCDVERSION-linux-$(dpkg --print-architecture).tar.gz" \
             | tar xz -C /usr/local/bin --strip=1 --wildcards --no-anchored etcd etcdctl \
 \
-    # Download confd
-    && curl -sL https://github.com/kelseyhightower/confd/releases/download/v${CONFDVERSION}/confd-${CONFDVERSION}-linux-amd64 \
-            > /usr/local/bin/confd && chmod +x /usr/local/bin/confd \
+    && if [ $(dpkg --print-architecture) = 'arm64' ]; then \
+        # Build confd
+        apt-get install -y git make \
+        && curl -sL https://go.dev/dl/go1.20.4.linux-arm64.tar.gz | tar xz -C /usr/local go \
+        && export GOROOT=/usr/local/go && export PATH=$PATH:$GOROOT/bin \
+        && git clone --recurse-submodules https://github.com/kelseyhightower/confd.git \
+        && make -C confd \
+        && cp confd/bin/confd /usr/local/bin/confd \
+        && rm -rf /confd /usr/local/go; \
+    else \
+        # Download confd
+        curl -sL "https://github.com/kelseyhightower/confd/releases/download/v$CONFDVERSION/confd-$CONFDVERSION-linux-$(dpkg --print-architecture)" \
+            > /usr/local/bin/confd && chmod +x /usr/local/bin/confd; \
+    fi \
 \
     # Clean up all useless packages and some files
     && apt-get purge -y --allow-remove-essential python3-pip gzip bzip2 util-linux e2fsprogs \
                 libmagic1 bsdmainutils login ncurses-bin libmagic-mgc e2fslibs bsdutils \
-                exim4-config gnupg-agent dirmngr libpython2.7-stdlib libpython2.7-minimal \
+                exim4-config gnupg-agent dirmngr \
+                git make \
     && apt-get autoremove -y \
     && apt-get clean -y \
     && rm -rf /var/lib/apt/lists/* \
@@ -83,14 +94,14 @@ RUN set -ex \
         /usr/share/locale/??_?? \
         /usr/share/postgresql/*/man \
         /usr/share/postgresql-common/pg_wrapper \
-        /usr/share/vim/vim80/doc \
-        /usr/share/vim/vim80/lang \
-        /usr/share/vim/vim80/tutor \
+        /usr/share/vim/vim*/doc \
+        /usr/share/vim/vim*/lang \
+        /usr/share/vim/vim*/tutor \
 #        /var/lib/dpkg/info/* \
     && find /usr/bin -xtype l -delete \
     && find /var/log -type f -exec truncate --size 0 {} \; \
     && find /usr/lib/python3/dist-packages -name '*test*' | xargs rm -fr \
-    && find /lib/x86_64-linux-gnu/security -type f ! -name pam_env.so ! -name pam_permit.so ! -name pam_unix.so -delete
+    && find /lib/$(uname -m)-linux-gnu/security -type f ! -name pam_env.so ! -name pam_permit.so ! -name pam_unix.so -delete
 
 # perform compression if it is necessary
 ARG COMPRESS
@@ -99,8 +110,10 @@ RUN if [ "$COMPRESS" = "true" ]; then \
         # Allow certain sudo commands from postgres
         && echo 'postgres ALL=(ALL) NOPASSWD: /bin/tar xpJf /a.tar.xz -C /, /bin/rm /a.tar.xz, /bin/ln -snf dash /bin/sh' >> /etc/sudoers \
         && ln -snf busybox /bin/sh \
-        && files="/bin/sh /usr/bin/sudo /usr/lib/sudo/sudoers.so /lib/x86_64-linux-gnu/security/pam_*.so" \
-        && libs="$(ldd $files | awk '{print $3;}' | grep '^/' | sort -u) /lib/x86_64-linux-gnu/ld-linux-x86-64.so.* /lib/x86_64-linux-gnu/libnsl.so.* /lib/x86_64-linux-gnu/libnss_compat.so.*" \
+        && arch=$(uname -m) \
+        && darch=$(uname -m | sed 's/_/-/') \
+        && files="/bin/sh /usr/bin/sudo /usr/lib/sudo/sudoers.so /lib/$arch-linux-gnu/security/pam_*.so" \
+        && libs="$(ldd $files | awk '{print $3;}' | grep '^/' | sort -u) /lib/ld-linux-$darch.so.* /lib/$arch-linux-gnu/ld-linux-$darch.so.* /lib/$arch-linux-gnu/libnsl.so.* /lib/$arch-linux-gnu/libnss_compat.so.* /lib/$arch-linux-gnu/libnss_files.so.*" \
         && (echo /var/run $files $libs | tr ' ' '\n' && realpath $files $libs) | sort -u | sed 's/^\///' > /exclude \
         && find /etc/alternatives -xtype l -delete \
         && save_dirs="usr lib var bin sbin etc/ssl etc/init.d etc/alternatives etc/apt" \
@@ -130,6 +143,7 @@ ARG PGBIN=/usr/lib/postgresql/$PG_MAJOR/bin
 
 ENV LC_ALL=$LC_ALL LANG=$LANG EDITOR=/usr/bin/editor
 ENV PGDATA=$PGDATA PATH=$PATH:$PGBIN
+ENV ETCDCTL_API=3
 
 COPY patroni /patroni/
 COPY extras/confd/conf.d/haproxy.toml /etc/confd/conf.d/
@@ -141,17 +155,18 @@ WORKDIR $PGHOME
 
 RUN sed -i 's/env python/&3/' /patroni*.py \
     # "fix" patroni configs
-    && sed -i 's/^\(  connect_address:\|  - host\)/#&/' postgres?.yml \
     && sed -i 's/^  listen: 127.0.0.1/  listen: 0.0.0.0/' postgres?.yml \
     && sed -i "s|^\(  data_dir: \).*|\1$PGDATA|" postgres?.yml \
     && sed -i "s|^#\(  bin_dir: \).*|\1$PGBIN|" postgres?.yml \
     && sed -i 's/^  - encoding: UTF8/  - locale: en_US.UTF-8\n&/' postgres?.yml \
-    && sed -i 's/^\(scope\|name\|etcd\|  host\|  authentication\|  pg_hba\|  parameters\):/#&/' postgres?.yml \
+    && sed -i 's/^\(scope\|name\|etcd\|  host\|  authentication\|  connect_address\|  parameters\):/#&/' postgres?.yml \
     && sed -i 's/^    \(replication\|superuser\|rewind\|unix_socket_directories\|\(\(  \)\{0,1\}\(username\|password\)\)\):/#&/' postgres?.yml \
-    && sed -i 's/^      parameters:/      pg_hba:\n      - local all all trust\n      - host replication all all md5\n      - host all all all md5\n&\n        max_connections: 100/'  postgres?.yml \
+    && sed -i 's/^      parameters:/&\n        max_connections: 100/'  postgres?.yml \
+    && sed -i 's/^      pg_hba:/&\n      - local all all trust/' postgres?.yml \
+    && sed -i 's/^\(.*\) \(.*\) md5/\1 all md5/' postgres?.yml \
     && if [ "$COMPRESS" = "true" ]; then chmod u+s /usr/bin/sudo; fi \
     && chmod +s /bin/ping \
-    && chown -R postgres:postgres $PGHOME /run /etc/haproxy
+    && chown -R postgres:postgres "$PGHOME" /run /etc/haproxy
 
 USER postgres
 

Dockerfile.citus

@@ -0,0 +1,201 @@
+## This Dockerfile is meant to aid in the building and debugging patroni whilst developing on your local machine
+## It has all the necessary components to play/debug with a single node appliance, running etcd
+ARG PG_MAJOR=16
+ARG COMPRESS=false
+ARG PGHOME=/home/postgres
+ARG PGDATA=$PGHOME/data
+ARG LC_ALL=C.UTF-8
+ARG LANG=C.UTF-8
+
+FROM postgres:$PG_MAJOR as builder
+
+ARG PGHOME
+ARG PGDATA
+ARG LC_ALL
+ARG LANG
+
+ENV ETCDVERSION=3.3.13 CONFDVERSION=0.16.0
+
+RUN set -ex \
+    && export DEBIAN_FRONTEND=noninteractive \
+    && echo 'APT::Install-Recommends "0";\nAPT::Install-Suggests "0";' > /etc/apt/apt.conf.d/01norecommend \
+    && apt-get update -y \
+    # postgres:PG_MAJOR is based on debian, which has the patroni package. We will install all required dependencies
+    && apt-cache depends patroni | sed -n -e 's/.*Depends: \(python3-.\+\)$/\1/p' \
+            | grep -Ev '^python3-(sphinx|etcd|consul|kazoo|kubernetes)' \
+            | xargs apt-get install -y vim curl less jq locales haproxy sudo \
+                            python3-etcd python3-kazoo python3-pip busybox \
+                            net-tools iputils-ping lsb-release dumb-init --fix-missing \
+    && if [ $(dpkg --print-architecture) = 'arm64' ]; then \
+        apt-get install -y postgresql-server-dev-$PG_MAJOR \
+                           git gcc make autoconf \
+                           libc6-dev flex libcurl4-gnutls-dev \
+                           libicu-dev libkrb5-dev liblz4-dev \
+                           libpam0g-dev libreadline-dev libselinux1-dev\
+                           libssl-dev libxslt1-dev libzstd-dev uuid-dev \
+        && git clone -b "main" https://github.com/citusdata/citus.git \
+        && MAKEFLAGS="-j $(grep -c ^processor /proc/cpuinfo)" \
+        && cd citus && ./configure && make install && cd ../ && rm -rf /citus; \
+    else \
+        echo "deb [signed-by=/etc/apt/trusted.gpg.d/citusdata_community.gpg] https://packagecloud.io/citusdata/community/debian/ $(lsb_release -cs) main" > /etc/apt/sources.list.d/citusdata_community.list \
+        && curl -sL https://packagecloud.io/citusdata/community/gpgkey | gpg --dearmor > /etc/apt/trusted.gpg.d/citusdata_community.gpg \
+        && apt-get update -y \
+        && apt-get -y install postgresql-$PG_MAJOR-citus-12.1; \
+    fi \
+\
+    # Cleanup all locales but en_US.UTF-8
+    && find /usr/share/i18n/charmaps/ -type f ! -name UTF-8.gz -delete \
+    && find /usr/share/i18n/locales/ -type f ! -name en_US ! -name en_GB ! -name i18n* ! -name iso14651_t1 ! -name iso14651_t1_common ! -name 'translit_*' -delete \
+    && echo 'en_US.UTF-8 UTF-8' > /usr/share/i18n/SUPPORTED \
+\
+    # Make sure we have a en_US.UTF-8 locale available
+    && localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8 \
+\
+    # haproxy dummy config
+    && echo 'global\n        stats socket /run/haproxy/admin.sock mode 660 level admin' > /etc/haproxy/haproxy.cfg \
+\
+    # vim config
+    && echo 'syntax on\nfiletype plugin indent on\nset mouse-=a\nautocmd FileType yaml setlocal ts=2 sts=2 sw=2 expandtab' > /etc/vim/vimrc.local \
+\
+    # Prepare postgres/patroni/haproxy environment
+    && mkdir -p $PGHOME/.config/patroni /patroni /run/haproxy \
+    && ln -s ../../postgres0.yml $PGHOME/.config/patroni/patronictl.yaml \
+    && ln -s /patronictl.py /usr/local/bin/patronictl \
+    && sed -i "s|/var/lib/postgresql.*|$PGHOME:/bin/bash|" /etc/passwd \
+    && chown -R postgres:postgres /var/log \
+\
+    # Download etcd
+    && curl -sL https://github.com/coreos/etcd/releases/download/v${ETCDVERSION}/etcd-v${ETCDVERSION}-linux-$(dpkg --print-architecture).tar.gz \
+            | tar xz -C /usr/local/bin --strip=1 --wildcards --no-anchored etcd etcdctl \
+\
+    && if [ $(dpkg --print-architecture) = 'arm64' ]; then \
+        # Build confd
+        curl -sL https://go.dev/dl/go1.20.4.linux-arm64.tar.gz | tar xz -C /usr/local go \
+        && export GOROOT=/usr/local/go && export PATH=$PATH:$GOROOT/bin \
+        && git clone --recurse-submodules https://github.com/kelseyhightower/confd.git \
+        && make -C confd \
+        && cp confd/bin/confd /usr/local/bin/confd \
+        && rm -rf /confd /usr/local/go; \
+    else \
+        # Download confd
+        curl -sL "https://github.com/kelseyhightower/confd/releases/download/v$CONFDVERSION/confd-$CONFDVERSION-linux-$(dpkg --print-architecture)" \
+            > /usr/local/bin/confd && chmod +x /usr/local/bin/confd; \
+    fi \
+    # Prepare client cert for HAProxy
+    && cat /etc/ssl/private/ssl-cert-snakeoil.key  /etc/ssl/certs/ssl-cert-snakeoil.pem > /etc/ssl/private/ssl-cert-snakeoil.crt \
+\
+    # Clean up all useless packages and some files
+    && apt-get purge -y --allow-remove-essential python3-pip gzip bzip2 util-linux e2fsprogs \
+                libmagic1 bsdmainutils login ncurses-bin libmagic-mgc e2fslibs bsdutils \
+                exim4-config gnupg-agent dirmngr \
+                postgresql-server-dev-$PG_MAJOR git gcc make autoconf \
+                libc6-dev flex libicu-dev libkrb5-dev liblz4-dev \
+                libpam0g-dev libreadline-dev libselinux1-dev libssl-dev libxslt1-dev libzstd-dev uuid-dev \
+    && apt-get autoremove -y \
+    && apt-get clean -y \
+    && rm -rf /var/lib/apt/lists/* \
+        /root/.cache \
+        /var/cache/debconf/* \
+        /etc/rc?.d \
+        /etc/systemd \
+        /docker-entrypoint* \
+        /sbin/pam* \
+        /sbin/swap* \
+        /sbin/unix* \
+        /usr/local/bin/gosu \
+        /usr/sbin/[acgipr]* \
+        /usr/sbin/*user* \
+        /usr/share/doc* \
+        /usr/share/man \
+        /usr/share/info \
+        /usr/share/i18n/locales/translit_hangul \
+        /usr/share/locale/?? \
+        /usr/share/locale/??_?? \
+        /usr/share/postgresql/*/man \
+        /usr/share/postgresql-common/pg_wrapper \
+        /usr/share/vim/vim*/doc \
+        /usr/share/vim/vim*/lang \
+        /usr/share/vim/vim*/tutor \
+#        /var/lib/dpkg/info/* \
+    && find /usr/bin -xtype l -delete \
+    && find /var/log -type f -exec truncate --size 0 {} \; \
+    && find /usr/lib/python3/dist-packages -name '*test*' | xargs rm -fr \
+    && find /lib/$(uname -m)-linux-gnu/security -type f ! -name pam_env.so ! -name pam_permit.so ! -name pam_unix.so -delete
+
+# perform compression if it is necessary
+ARG COMPRESS
+RUN if [ "$COMPRESS" = "true" ]; then \
+        set -ex \
+        # Allow certain sudo commands from postgres
+        && echo 'postgres ALL=(ALL) NOPASSWD: /bin/tar xpJf /a.tar.xz -C /, /bin/rm /a.tar.xz, /bin/ln -snf dash /bin/sh' >> /etc/sudoers \
+        && ln -snf busybox /bin/sh \
+        && arch=$(uname -m) \
+        && darch=$(uname -m | sed 's/_/-/') \
+        && files="/bin/sh /usr/bin/sudo /usr/lib/sudo/sudoers.so /lib/$arch-linux-gnu/security/pam_*.so" \
+        && libs="$(ldd $files | awk '{print $3;}' | grep '^/' | sort -u) /lib/ld-linux-$darch.so.* /lib/$arch-linux-gnu/ld-linux-$darch.so.* /lib/$arch-linux-gnu/libnsl.so.* /lib/$arch-linux-gnu/libnss_compat.so.* /lib/$arch-linux-gnu/libnss_files.so.*" \
+        && (echo /var/run $files $libs | tr ' ' '\n' && realpath $files $libs) | sort -u | sed 's/^\///' > /exclude \
+        && find /etc/alternatives -xtype l -delete \
+        && save_dirs="usr lib var bin sbin etc/ssl etc/init.d etc/alternatives etc/apt" \
+        && XZ_OPT=-e9v tar -X /exclude -cpJf a.tar.xz $save_dirs \
+        # we call "cat /exclude" to avoid including files from the $save_dirs that are also among
+        # the exceptions listed in the /exclude, as "uniq -u" eliminates all non-unique lines.
+        # By calling "cat /exclude" a second time we guarantee that there will be at least two lines
+        # for each exception and therefore they will be excluded from the output passed to 'rm'.
+        && /bin/busybox sh -c "(find $save_dirs -not -type d && cat /exclude /exclude && echo exclude) | sort | uniq -u | xargs /bin/busybox rm" \
+        && /bin/busybox --install -s \
+        && /bin/busybox sh -c "find $save_dirs -type d -depth -exec rmdir -p {} \; 2> /dev/null"; \
+    else \
+        /bin/busybox --install -s; \
+    fi
+
+FROM scratch
+COPY --from=builder / /
+
+LABEL maintainer="Alexander Kukushkin <[email protected]>"
+
+ARG PG_MAJOR
+ARG COMPRESS
+ARG PGHOME
+ARG PGDATA
+ARG LC_ALL
+ARG LANG
+
+ARG PGBIN=/usr/lib/postgresql/$PG_MAJOR/bin
+
+ENV LC_ALL=$LC_ALL LANG=$LANG EDITOR=/usr/bin/editor
+ENV PGDATA=$PGDATA PATH=$PATH:$PGBIN
+ENV ETCDCTL_API=3
+
+COPY patroni /patroni/
+COPY extras/confd/conf.d/haproxy.toml /etc/confd/conf.d/
+COPY extras/confd/templates/haproxy-citus.tmpl /etc/confd/templates/haproxy.tmpl
+COPY patroni*.py docker/entrypoint.sh /
+COPY postgres?.yml $PGHOME/
+
+WORKDIR $PGHOME
+
+RUN sed -i 's/env python/&3/' /patroni*.py \
+    # "fix" patroni configs
+    && sed -i 's/^  listen: 127.0.0.1/  listen: 0.0.0.0/' postgres?.yml \
+    && sed -i "s|^\(  data_dir: \).*|\1$PGDATA|" postgres?.yml \
+    && sed -i "s|^#\(  bin_dir: \).*|\1$PGBIN|" postgres?.yml \
+    && sed -i 's/^  - encoding: UTF8/  - locale: en_US.UTF-8\n&/' postgres?.yml \
+    && sed -i 's/^scope:/log:\n  loggers:\n    patroni.postgresql.citus: DEBUG\n#&/' postgres?.yml \
+    && sed -i 's/^\(name\|etcd\|  host\|  authentication\|  connect_address\|  parameters\):/#&/' postgres?.yml \
+    && sed -i 's/^    \(replication\|superuser\|rewind\|unix_socket_directories\|\(\(  \)\{0,1\}\(username\|password\)\)\):/#&/' postgres?.yml \
+    && sed -i 's/^postgresql:/&\n  basebackup:\n    checkpoint: fast/' postgres?.yml \
+    && sed -i 's|^      parameters:|&\n        max_connections: 100\n        shared_buffers: 16MB\n        ssl: "on"\n        ssl_ca_file: /etc/ssl/certs/ssl-cert-snakeoil.pem\n        ssl_cert_file: /etc/ssl/certs/ssl-cert-snakeoil.pem\n        ssl_key_file: /etc/ssl/private/ssl-cert-snakeoil.key\n        citus.node_conninfo: "sslrootcert=/etc/ssl/certs/ssl-cert-snakeoil.pem sslkey=/etc/ssl/private/ssl-cert-snakeoil.key sslcert=/etc/ssl/certs/ssl-cert-snakeoil.pem sslmode=verify-ca"|'  postgres?.yml \
+    && sed -i 's/^      pg_hba:/&\n      - local all all trust/' postgres?.yml \
+    && sed -i 's/^\(.*\) \(.*\) \(.*\) \(.*\) \(.*\) md5.*$/\1 hostssl \3 \4 all md5 clientcert=verify-ca/' postgres?.yml \
+    && sed -i 's/^#\(ctl\|  certfile\|  keyfile\)/\1/' postgres?.yml \
+    && sed -i 's|^#  cafile: .*$|  verify_client: required\n  cafile: /etc/ssl/certs/ssl-cert-snakeoil.pem|' postgres?.yml \
+    && sed -i 's|^#  cacert: .*$|  cacert: /etc/ssl/certs/ssl-cert-snakeoil.pem|' postgres?.yml \
+    && sed -i 's/^#  insecure: .*/  insecure: on/' postgres?.yml \
+    # client cert for HAProxy to access Patroni REST API
+    && if [ "$COMPRESS" = "true" ]; then chmod u+s /usr/bin/sudo; fi \
+    && chmod +s /bin/ping \
+    && chown -R postgres:postgres $PGHOME /run /etc/haproxy
+
+USER postgres
+
+ENTRYPOINT ["/bin/sh", "/entrypoint.sh"]

README.rst

@@ -8,11 +8,13 @@ You can find a version of this documentation that is searchable and also easier
 
 There are many ways to run high availability with PostgreSQL; for a list, see the `PostgreSQL Documentation <https://wiki.postgresql.org/wiki/Replication,_Clustering,_and_Connection_Pooling>`__.
 
-Patroni is a template for you to create your own customized, high-availability solution using Python and - for maximum accessibility - a distributed configuration store like `ZooKeeper <https://zookeeper.apache.org/>`__, `etcd <https://github.com/coreos/etcd>`__, `Consul <https://github.com/hashicorp/consul>`__ or `Kubernetes <https://kubernetes.io>`__. Database engineers, DBAs, DevOps engineers, and SREs who are looking to quickly deploy HA PostgreSQL in the datacenter-or anywhere else-will hopefully find it useful.
+Patroni is a template for high availability (HA) PostgreSQL solutions using Python. For maximum accessibility, Patroni supports a variety of distributed configuration stores like `ZooKeeper <https://zookeeper.apache.org/>`__, `etcd <https://github.com/coreos/etcd>`__, `Consul <https://github.com/hashicorp/consul>`__ or `Kubernetes <https://kubernetes.io>`__. Database engineers, DBAs, DevOps engineers, and SREs who are looking to quickly deploy HA PostgreSQL in datacenters - or anywhere else - will hopefully find it useful.
 
 We call Patroni a "template" because it is far from being a one-size-fits-all or plug-and-play replication system. It will have its own caveats. Use wisely.
 
-Currently supported PostgreSQL versions: 9.3 to 15.
+Currently supported PostgreSQL versions: 9.3 to 16.
+
+**Note to Citus users**: Starting from 3.0 Patroni nicely integrates with the `Citus <https://github.com/citusdata/citus>`__ database extension to Postgres. Please check the `Citus support page <https://github.com/zalando/patroni/blob/master/docs/citus.rst>`__ in the Patroni documentation for more info about how to use Patroni high availability together with a Citus distributed cluster.
 
 **Note to Kubernetes users**: Patroni can run natively on top of Kubernetes. Take a look at the `Kubernetes <https://github.com/zalando/patroni/blob/master/docs/kubernetes.rst>`__ chapter of the Patroni documentation.
 
@@ -47,7 +49,7 @@ We report new releases information `here <https://github.com/zalando/patroni/rel
 Community
 =========
 
-There are two places to connect with the Patroni community: `on github <https://github.com/zalando/patroni>`__, via Issues and PRs, and on channel #patroni in the `PostgreSQL Slack <https://postgres-slack.herokuapp.com/>`__.  If you're using Patroni, or just interested, please join us.
+There are two places to connect with the Patroni community: `on github <https://github.com/zalando/patroni>`__, via Issues and PRs, and on channel `#patroni <https://postgresteam.slack.com/archives/C9XPYG92A>`__ in the `PostgreSQL Slack <https://pgtreats.info/slack-invite>`__.  If you're using Patroni, or just interested, please join us.
 
 ===================================
 Technical Requirements/Installation
@@ -72,27 +74,11 @@ There are a few options available:
 
 ::
 
-    sudo apt-get install python-psycopg2   # install python2 psycopg2 module on Debian/Ubuntu
-    sudo apt-get install python3-psycopg2  # install python3 psycopg2 module on Debian/Ubuntu
-    sudo yum install python-psycopg2       # install python2 psycopg2 on RedHat/Fedora/CentOS
+    sudo apt-get install python3-psycopg2  # install psycopg2 module on Debian/Ubuntu
+    sudo yum install python3-psycopg2      # install psycopg2 on RedHat/Fedora/CentOS
 
-2. Install psycopg2 from the binary package
+2. Specify one of `psycopg`, `psycopg2`, or `psycopg2-binary` in the list of dependencies when installing Patroni with pip (see below).
 
-::
-
-    pip install psycopg2-binary
-
-3. Install psycopg2 from source
-
-::
-
-    pip install psycopg2>=2.5.4
-
-4. Use psycopg 3.0 instead of psycopg2
-
-::
-
-    pip install psycopg[binary]
 
 **General installation for pip**
 
@@ -117,13 +103,21 @@ kubernetes
 raft
     `pysyncobj` module in order to use python Raft implementation as DCS
 aws
-    `boto` in order to use AWS callbacks
+    `boto3` in order to use AWS callbacks
+all
+    all of the above (except psycopg family)
+psycopg3
+    `psycopg[binary]>=3.0.0` module
+psycopg2
+    `psycopg2>=2.5.4` module
+psycopg2-binary
+    `psycopg2-binary` module
 
-For example, the command in order to install Patroni together with dependencies for Etcd as a DCS and AWS callbacks is:
+For example, the command in order to install Patroni together with psycopg3, dependencies for Etcd as a DCS, and AWS callbacks is:
 
 ::
 
-    pip install patroni[etcd,aws]
+    pip install patroni[psycopg3,etcd3,aws]
 
 Note that external tools to call in the replica creation or custom bootstrap scripts (i.e. WAL-E) should be installed independently of Patroni.
 
@@ -157,7 +151,7 @@ run:
 YAML Configuration
 ==================
 
-Go `here <https://github.com/zalando/patroni/blob/master/docs/SETTINGS.rst>`__ for comprehensive information about settings for etcd, consul, and ZooKeeper. And for an example, see `postgres0.yml <https://github.com/zalando/patroni/blob/master/postgres0.yml>`__.
+Go `here <https://github.com/zalando/patroni/blob/master/docs/dynamic_configuration.rst>`__ for comprehensive information about settings for etcd, consul, and ZooKeeper. And for an example, see `postgres0.yml <https://github.com/zalando/patroni/blob/master/postgres0.yml>`__.
 
 =========================
 Environment Configuration

TODO.md

@@ -1,12 +0,0 @@
-Failover
-========
-- When determining who should become master, include the minor version of PostgreSQL in the decision.
-
-Configuration
-==============
-- Provide a way to change pg_hba.conf of a running cluster on the Patroni level, without changing individual nodes.
-- Provide hooks to store and retrieve cluster-wide passwords without exposing them in a plain-text form to unauthorized users.
-
-Documentation
-==============
-- Document how to run cascading replication and possibly initialize the cluster without an access to the master node.

docker-compose-citus.yml

@@ -0,0 +1,138 @@
+# docker compose file for running a Citus cluster
+# with 3-node etcd v3 cluster as the DCS and one haproxy node.
+# The Citus cluster has a coordinator (3 nodes)
+# and two worker clusters (2 nodes).
+#
+# Before starting it up you need to build the docker image:
+# $ docker build -f Dockerfile.citus -t patroni-citus .
+# The cluster could be started as:
+# $ docker-compose -f docker-compose-citus.yml up -d
+# You can read more about it in the:
+# https://github.com/zalando/patroni/blob/master/docker/README.md#citus-cluster
+version: "2"
+
+networks:
+    demo:
+
+services:
+    etcd1: &etcd
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        environment:
+            ETCD_LISTEN_PEER_URLS: http://0.0.0.0:2380
+            ETCD_LISTEN_CLIENT_URLS: http://0.0.0.0:2379
+            ETCD_INITIAL_CLUSTER: etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
+            ETCD_INITIAL_CLUSTER_STATE: new
+            ETCD_INITIAL_CLUSTER_TOKEN: tutorial
+            ETCD_UNSUPPORTED_ARCH: arm64
+        container_name: demo-etcd1
+        hostname: etcd1
+        command: etcd --name etcd1 --initial-advertise-peer-urls http://etcd1:2380
+
+    etcd2:
+        <<: *etcd
+        container_name: demo-etcd2
+        hostname: etcd2
+        command: etcd --name etcd2 --initial-advertise-peer-urls http://etcd2:2380
+
+    etcd3:
+        <<: *etcd
+        container_name: demo-etcd3
+        hostname: etcd3
+        command: etcd --name etcd3 --initial-advertise-peer-urls http://etcd3:2380
+
+    haproxy:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: haproxy
+        container_name: demo-haproxy
+        ports:
+            - "5000:5000"  # Access to the coorinator primary
+            - "5001:5001"  # Load-balancing across workers primaries
+        command: haproxy
+        environment: &haproxy_env
+            ETCDCTL_ENDPOINTS: http://etcd1:2379,http://etcd2:2379,http://etcd3:2379
+            PATRONI_ETCD3_HOSTS: "'etcd1:2379','etcd2:2379','etcd3:2379'"
+            PATRONI_SCOPE: demo
+            PATRONI_CITUS_GROUP: 0
+            PATRONI_CITUS_DATABASE: citus
+            PGSSLMODE: verify-ca
+            PGSSLKEY: /etc/ssl/private/ssl-cert-snakeoil.key
+            PGSSLCERT: /etc/ssl/certs/ssl-cert-snakeoil.pem
+            PGSSLROOTCERT: /etc/ssl/certs/ssl-cert-snakeoil.pem
+
+    coord1:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: coord1
+        container_name: demo-coord1
+        environment: &coord_env
+            <<: *haproxy_env
+            PATRONI_NAME: coord1
+            PATRONI_CITUS_GROUP: 0
+
+    coord2:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: coord2
+        container_name: demo-coord2
+        environment:
+            <<: *coord_env
+            PATRONI_NAME: coord2
+
+    coord3:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: coord3
+        container_name: demo-coord3
+        environment:
+            <<: *coord_env
+            PATRONI_NAME: coord3
+
+
+    work1-1:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: work1-1
+        container_name: demo-work1-1
+        environment: &work1_env
+            <<: *haproxy_env
+            PATRONI_NAME: work1-1
+            PATRONI_CITUS_GROUP: 1
+
+    work1-2:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: work1-2
+        container_name: demo-work1-2
+        environment:
+            <<: *work1_env
+            PATRONI_NAME: work1-2
+
+
+    work2-1:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: work2-1
+        container_name: demo-work2-1
+        environment: &work2_env
+            <<: *haproxy_env
+            PATRONI_NAME: work2-1
+            PATRONI_CITUS_GROUP: 2
+
+    work2-2:
+        image: ${PATRONI_TEST_IMAGE:-patroni-citus}
+        networks: [ demo ]
+        env_file: docker/patroni.env
+        hostname: work2-2
+        container_name: demo-work2-2
+        environment:
+            <<: *work2_env
+            PATRONI_NAME: work2-2

docker-compose.yml

@@ -1,5 +1,12 @@
 # docker compose file for running a 3-node PostgreSQL cluster
 # with 3-node etcd cluster as the DCS and one haproxy node
+#
+# requires a patroni image build from the Dockerfile:
+# $ docker build -t patroni .
+# The cluster could be started as:
+# $ docker-compose up -d
+# You can read more about it in the:
+# https://github.com/zalando/patroni/blob/master/docker/README.md
 version: "2"
 
 networks:
@@ -7,7 +14,7 @@ networks:
 
 services:
     etcd1: &etcd
-        image: patroni
+        image: ${PATRONI_TEST_IMAGE:-patroni}
         networks: [ demo ]
         environment:
             ETCD_LISTEN_PEER_URLS: http://0.0.0.0:2380
@@ -15,24 +22,25 @@ services:
             ETCD_INITIAL_CLUSTER: etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
             ETCD_INITIAL_CLUSTER_STATE: new
             ETCD_INITIAL_CLUSTER_TOKEN: tutorial
+            ETCD_UNSUPPORTED_ARCH: arm64
         container_name: demo-etcd1
         hostname: etcd1
-        command: etcd -name etcd1 -initial-advertise-peer-urls http://etcd1:2380
+        command: etcd --name etcd1 --initial-advertise-peer-urls http://etcd1:2380
 
     etcd2:
         <<: *etcd
         container_name: demo-etcd2
         hostname: etcd2
-        command: etcd -name etcd2 -initial-advertise-peer-urls http://etcd2:2380
+        command: etcd --name etcd2 --initial-advertise-peer-urls http://etcd2:2380
 
     etcd3:
         <<: *etcd
         container_name: demo-etcd3
         hostname: etcd3
-        command: etcd -name etcd3 -initial-advertise-peer-urls http://etcd3:2380
+        command: etcd --name etcd3 --initial-advertise-peer-urls http://etcd3:2380
 
     haproxy:
-        image: patroni
+        image: ${PATRONI_TEST_IMAGE:-patroni}
         networks: [ demo ]
         env_file: docker/patroni.env
         hostname: haproxy
@@ -47,7 +55,7 @@ services:
             PATRONI_SCOPE: demo
 
     patroni1:
-        image: patroni
+        image: ${PATRONI_TEST_IMAGE:-patroni}
         networks: [ demo ]
         env_file: docker/patroni.env
         hostname: patroni1
@@ -57,7 +65,7 @@ services:
             PATRONI_NAME: patroni1
 
     patroni2:
-        image: patroni
+        image: ${PATRONI_TEST_IMAGE:-patroni}
         networks: [ demo ]
         env_file: docker/patroni.env
         hostname: patroni2
@@ -67,7 +75,7 @@ services:
             PATRONI_NAME: patroni2
 
     patroni3:
-        image: patroni
+        image: ${PATRONI_TEST_IMAGE:-patroni}
         networks: [ demo ]
         env_file: docker/patroni.env
         hostname: patroni3

docker/README.md

@@ -1,10 +1,10 @@
-# Patroni Dockerfile
-You can run Patroni in a docker container using this Dockerfile
+# Dockerfile and Dockerfile.citus
+You can run Patroni in a docker container using these Dockerfiles
 
-This Dockerfile is meant in aiding development of Patroni and quick testing of features. It is not a production-worthy
-Dockerfile
+They are meant in aiding development of Patroni and quick testing of features and not a production-worthy!
 
     docker build -t patroni .
+    docker build -f Dockerfile.citus -t patroni-citus .
 
 # Examples
 
@@ -12,106 +12,295 @@ Dockerfile
 
     docker run -d patroni
 
-## Three-node Patroni cluster with three-node etcd cluster and one haproxy container using docker-compose
+## Three-node Patroni cluster
+
+In addition to three Patroni containers the stack starts three containers with etcd (forming a three-node cluster), and one container with haproxy.
+The haproxy listens on ports 5000 (connects to the primary) and 5001 (does load-balancing between healthy standbys).
 
 Example session:
 
-    $ docker-compose up -d
-    Creating demo-haproxy ...
-    Creating demo-patroni2 ...
-    Creating demo-patroni1 ...
-    Creating demo-patroni3 ...
-    Creating demo-etcd2 ...
-    Creating demo-etcd1 ...
-    Creating demo-etcd3 ...
-    Creating demo-haproxy
-    Creating demo-patroni2
-    Creating demo-patroni1
-    Creating demo-patroni3
-    Creating demo-etcd1
-    Creating demo-etcd2
-    Creating demo-etcd2 ... done
+    $ docker compose up -d
+    ✔ Network patroni_demo     Created
+    ✔ Container demo-etcd1     Started
+    ✔ Container demo-haproxy   Started
+    ✔ Container demo-patroni1  Started
+    ✔ Container demo-patroni2  Started
+    ✔ Container demo-patroni3  Started
+    ✔ Container demo-etcd2     Started
+    ✔ Container demo-etcd3     Started
 
     $ docker ps
-    CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                              NAMES
-    5b7a90b4cfbf        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 27 seconds                                          demo-etcd2
-    e30eea5222f2        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 27 seconds                                          demo-etcd1
-    83bcf3cb208f        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 27 seconds                                          demo-etcd3
-    922532c56e7d        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 28 seconds                                          demo-patroni3
-    14f875e445f3        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 28 seconds                                          demo-patroni2
-    110d1073b383        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 28 seconds                                          demo-patroni1
-    5af5e6e36028        patroni             "/bin/sh /entrypoint…"   29 seconds ago      Up 28 seconds       0.0.0.0:5000-5001->5000-5001/tcp   demo-haproxy
+    CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS                                                           NAMES
+    a37bcec56726   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes                                                                   demo-etcd3
+    034ab73868a8   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes                                                                   demo-patroni2
+    03837736f710   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes                                                                   demo-patroni3
+    22815c3d85b3   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes                                                                   demo-etcd2
+    814b4304d132   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes   0.0.0.0:5000-5001->5000-5001/tcp, :::5000-5001->5000-5001/tcp   demo-haproxy
+    6375b0ba2d0a   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes                                                                   demo-patroni1
+    aef8bf3ee91f   patroni   "/bin/sh /entrypoint…"   15 minutes ago   Up 15 minutes                                                                   demo-etcd1
 
     $ docker logs demo-patroni1
-    2019-02-20 08:19:32,714 INFO: Failed to import patroni.dcs.consul
-    2019-02-20 08:19:32,737 INFO: Selected new etcd server http://etcd3:2379
-    2019-02-20 08:19:35,140 INFO: Lock owner: None; I am patroni1
-    2019-02-20 08:19:35,174 INFO: trying to bootstrap a new cluster
+    2023-11-21 09:04:33,547 INFO: Selected new etcd server http://172.29.0.3:2379
+    2023-11-21 09:04:33,605 INFO: Lock owner: None; I am patroni1
+    2023-11-21 09:04:33,693 INFO: trying to bootstrap a new cluster
     ...
-    2019-02-20 08:19:39,310 INFO: postmaster pid=37
-    2019-02-20 08:19:39.314 UTC [37] LOG:  listening on IPv4 address "0.0.0.0", port 5432
-    2019-02-20 08:19:39.321 UTC [37] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
-    2019-02-20 08:19:39.353 UTC [39] LOG:  database system was shut down at 2019-02-20 08:19:36 UTC
-    2019-02-20 08:19:39.354 UTC [40] FATAL:  the database system is starting up
-    localhost:5432 - rejecting connections
-    2019-02-20 08:19:39.369 UTC [37] LOG:  database system is ready to accept connections
+    2023-11-21 09:04:34.920 UTC [43] LOG:  starting PostgreSQL 15.5 (Debian 15.5-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
+    2023-11-21 09:04:34.921 UTC [43] LOG:  listening on IPv4 address "0.0.0.0", port 5432
+    2023-11-21 09:04:34,922 INFO: postmaster pid=43
+    2023-11-21 09:04:34.922 UTC [43] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
+    2023-11-21 09:04:34.925 UTC [47] LOG:  database system was shut down at 2023-11-21 09:04:34 UTC
+    2023-11-21 09:04:34.928 UTC [43] LOG:  database system is ready to accept connections
     localhost:5432 - accepting connections
-    2019-02-20 08:19:39,383 INFO: establishing a new patroni connection to the postgres cluster
-    2019-02-20 08:19:39,408 INFO: running post_bootstrap
-    2019-02-20 08:19:39,432 WARNING: Could not activate Linux watchdog device: "Can't open watchdog device: [Errno 2] No such file or directory: '/dev/watchdog'"
-    2019-02-20 08:19:39,515 INFO: initialized a new cluster
-    2019-02-20 08:19:49,424 INFO: Lock owner: patroni1; I am patroni1
-    2019-02-20 08:19:49,447 INFO: Lock owner: patroni1; I am patroni1
-    2019-02-20 08:19:49,480 INFO: no action.  i am the leader with the lock
-    2019-02-20 08:19:59,422 INFO: Lock owner: patroni1; I am patroni1
+    localhost:5432 - accepting connections
+    2023-11-21 09:04:34,938 INFO: establishing a new patroni heartbeat connection to postgres
+    2023-11-21 09:04:34,992 INFO: running post_bootstrap
+    2023-11-21 09:04:35,004 WARNING: User creation via "bootstrap.users" will be removed in v4.0.0
+    2023-11-21 09:04:35,009 WARNING: Could not activate Linux watchdog device: Can't open watchdog device: [Errno 2] No such file or directory: '/dev/watchdog'
+    2023-11-21 09:04:35,189 INFO: initialized a new cluster
+    2023-11-21 09:04:35,328 INFO: no action. I am (patroni1), the leader with the lock
+    2023-11-21 09:04:43,824 INFO: establishing a new patroni restapi connection to postgres
+    2023-11-21 09:04:45,322 INFO: no action. I am (patroni1), the leader with the lock
+    2023-11-21 09:04:55,320 INFO: no action. I am (patroni1), the leader with the lock
+    ...
 
     $ docker exec -ti demo-patroni1 bash
     postgres@patroni1:~$ patronictl list
-    +---------+----------+------------+--------+---------+----+-----------+
-    | Cluster |  Member  |    Host    |  Role  |  State  | TL | Lag in MB |
-    +---------+----------+------------+--------+---------+----+-----------+
-    |   demo  | patroni1 | 172.22.0.3 | Leader | running |  1 |         0 |
-    |   demo  | patroni2 | 172.22.0.7 |        | running |  1 |         0 |
-    |   demo  | patroni3 | 172.22.0.4 |        | running |  1 |         0 |
-    +---------+----------+------------+--------+---------+----+-----------+
+    + Cluster: demo (7303838734793224214) --------+----+-----------+
+    | Member   | Host       | Role    | State     | TL | Lag in MB |
+    +----------+------------+---------+-----------+----+-----------+
+    | patroni1 | 172.29.0.2 | Leader  | running   |  1 |           |
+    | patroni2 | 172.29.0.6 | Replica | streaming |  1 |         0 |
+    | patroni3 | 172.29.0.5 | Replica | streaming |  1 |         0 |
+    +----------+------------+---------+-----------+----+-----------+
 
-    postgres@patroni1:~$ etcdctl ls --recursive --sort -p /service/demo
+    postgres@patroni1:~$ etcdctl get --keys-only --prefix /service/demo
     /service/demo/config
     /service/demo/initialize
     /service/demo/leader
-    /service/demo/members/
     /service/demo/members/patroni1
     /service/demo/members/patroni2
     /service/demo/members/patroni3
-    /service/demo/optime/
-    /service/demo/optime/leader
+    /service/demo/status
 
     postgres@patroni1:~$ etcdctl member list
-    1bab629f01fa9065: name=etcd3 peerURLs=http://etcd3:2380 clientURLs=http://etcd3:2379 isLeader=false
-    8ecb6af518d241cc: name=etcd2 peerURLs=http://etcd2:2380 clientURLs=http://etcd2:2379 isLeader=true
-    b2e169fcb8a34028: name=etcd1 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false
+    2bf3e2ceda5d5960, started, etcd2, http://etcd2:2380, http://172.29.0.3:2379
+    55b3264e129c7005, started, etcd3, http://etcd3:2380, http://172.29.0.7:2379
+    acce7233f8ec127e, started, etcd1, http://etcd1:2380, http://172.29.0.8:2379
+
+
     postgres@patroni1:~$ exit
 
-    $ psql -h localhost -p 5000 -U postgres -W
+    $ docker exec -ti demo-haproxy bash
+    postgres@haproxy:~$ psql -h localhost -p 5000 -U postgres -W
     Password: postgres
-    psql (11.2 (Ubuntu 11.2-1.pgdg18.04+1), server 10.7 (Debian 10.7-1.pgdg90+1))
+    psql (15.5 (Debian 15.5-1.pgdg120+1))
     Type "help" for help.
 
-    localhost/postgres=# select pg_is_in_recovery();
+    postgres=# SELECT pg_is_in_recovery();
      pg_is_in_recovery
     ───────────────────
      f
     (1 row)
 
-    localhost/postgres=# \q
+    postgres=# \q
 
-    $ psql -h localhost -p 5001 -U postgres -W
+    postgres@haproxy:~$ psql -h localhost -p 5001 -U postgres -W
     Password: postgres
-    psql (11.2 (Ubuntu 11.2-1.pgdg18.04+1), server 10.7 (Debian 10.7-1.pgdg90+1))
+    psql (15.5 (Debian 15.5-1.pgdg120+1))
     Type "help" for help.
 
-    localhost/postgres=# select pg_is_in_recovery();
+    postgres=# SELECT pg_is_in_recovery();
      pg_is_in_recovery
     ───────────────────
      t
     (1 row)
+
+## Citus cluster
+
+The stack starts three containers with etcd (forming a three-node etcd cluster), seven containers with Patroni+PostgreSQL+Citus (three coordinator nodes, and two worker clusters with two nodes each), and one container with haproxy.
+The haproxy listens on ports 5000 (connects to the coordinator primary) and 5001 (does load-balancing between worker primary nodes).
+
+Example session:
+
+    $ docker compose -f docker-compose-citus.yml up -d
+    ✔ Network patroni_demo    Created
+    ✔ Container demo-coord2   Started
+    ✔ Container demo-work2-2  Started
+    ✔ Container demo-etcd1    Started
+    ✔ Container demo-haproxy  Started
+    ✔ Container demo-work1-1  Started
+    ✔ Container demo-work2-1  Started
+    ✔ Container demo-work1-2  Started
+    ✔ Container demo-coord1   Started
+    ✔ Container demo-etcd3    Started
+    ✔ Container demo-coord3   Started
+    ✔ Container demo-etcd2    Started
+
+
+    $ docker ps
+    CONTAINER ID   IMAGE           COMMAND                  CREATED          STATUS          PORTS                                                           NAMES
+    79c95492fac9   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-etcd3
+    77eb82d0f0c1   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-work2-1
+    03dacd7267ef   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-etcd1
+    db9206c66f85   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-etcd2
+    9a0fef7b7dd4   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-work1-2
+    f06b031d99dc   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-work2-2
+    f7c58545f314   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-coord2
+    383f9e7e188a   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-work1-1
+    f02e96dcc9d6   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-coord3
+    6945834b7056   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes                                                                   demo-coord1
+    b96ca42f785d   patroni-citus   "/bin/sh /entrypoint…"   11 minutes ago   Up 11 minutes   0.0.0.0:5000-5001->5000-5001/tcp, :::5000-5001->5000-5001/tcp   demo-haproxy
+
+
+    $ docker logs demo-coord1
+    2023-11-21 09:36:14,293 INFO: Selected new etcd server http://172.30.0.4:2379
+    2023-11-21 09:36:14,390 INFO: Lock owner: None; I am coord1
+    2023-11-21 09:36:14,478 INFO: trying to bootstrap a new cluster
+    ...
+    2023-11-21 09:36:16,475 INFO: postmaster pid=52
+    localhost:5432 - no response
+    2023-11-21 09:36:16.495 UTC [52] LOG:  starting PostgreSQL 15.5 (Debian 15.5-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
+    2023-11-21 09:36:16.495 UTC [52] LOG:  listening on IPv4 address "0.0.0.0", port 5432
+    2023-11-21 09:36:16.496 UTC [52] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
+    2023-11-21 09:36:16.498 UTC [56] LOG:  database system was shut down at 2023-11-21 09:36:15 UTC
+    2023-11-21 09:36:16.501 UTC [52] LOG:  database system is ready to accept connections
+    localhost:5432 - accepting connections
+    localhost:5432 - accepting connections
+    2023-11-21 09:36:17,509 INFO: establishing a new patroni heartbeat connection to postgres
+    2023-11-21 09:36:17,569 INFO: running post_bootstrap
+    2023-11-21 09:36:17,593 WARNING: User creation via "bootstrap.users" will be removed in v4.0.0
+    2023-11-21 09:36:17,783 INFO: establishing a new patroni restapi connection to postgres
+    2023-11-21 09:36:17,969 WARNING: Could not activate Linux watchdog device: Can't open watchdog device: [Errno 2] No such file or directory: '/dev/watchdog'
+    2023-11-21 09:36:17.969 UTC [70] LOG:  starting maintenance daemon on database 16386 user 10
+    2023-11-21 09:36:17.969 UTC [70] CONTEXT:  Citus maintenance daemon for database 16386 user 10
+    2023-11-21 09:36:18.159 UTC [54] LOG:  checkpoint starting: immediate force wait
+    2023-11-21 09:36:18,162 INFO: initialized a new cluster
+    2023-11-21 09:36:18,164 INFO: Lock owner: coord1; I am coord1
+    2023-11-21 09:36:18,297 INFO: Enabled synchronous replication
+    2023-11-21 09:36:18,298 DEBUG: Adding the new task: PgDistNode(nodeid=None,group=0,host=172.30.0.3,port=5432,event=after_promote)
+    2023-11-21 09:36:18,298 DEBUG: Adding the new task: PgDistNode(nodeid=None,group=1,host=172.30.0.7,port=5432,event=after_promote)
+    2023-11-21 09:36:18,298 DEBUG: Adding the new task: PgDistNode(nodeid=None,group=2,host=172.30.0.8,port=5432,event=after_promote)
+    2023-11-21 09:36:18,299 DEBUG: query(SELECT nodeid, groupid, nodename, nodeport, noderole FROM pg_catalog.pg_dist_node WHERE noderole = 'primary', ())
+    2023-11-21 09:36:18,299 INFO: establishing a new patroni citus connection to postgres
+    2023-11-21 09:36:18,323 DEBUG: query(SELECT pg_catalog.citus_add_node(%s, %s, %s, 'primary', 'default'), ('172.30.0.7', 5432, 1))
+    2023-11-21 09:36:18,361 INFO: no action. I am (coord1), the leader with the lock
+    2023-11-21 09:36:18,393 DEBUG: query(SELECT pg_catalog.citus_add_node(%s, %s, %s, 'primary', 'default'), ('172.30.0.8', 5432, 2))
+    2023-11-21 09:36:28,164 INFO: Lock owner: coord1; I am coord1
+    2023-11-21 09:36:28,251 INFO: Assigning synchronous standby status to ['coord3']
+    server signaled
+    2023-11-21 09:36:28.435 UTC [52] LOG:  received SIGHUP, reloading configuration files
+    2023-11-21 09:36:28.436 UTC [52] LOG:  parameter "synchronous_standby_names" changed to "coord3"
+    2023-11-21 09:36:28.641 UTC [83] LOG:  standby "coord3" is now a synchronous standby with priority 1
+    2023-11-21 09:36:28.641 UTC [83] STATEMENT:  START_REPLICATION SLOT "coord3" 0/3000000 TIMELINE 1
+    2023-11-21 09:36:30,582 INFO: Synchronous standby status assigned to ['coord3']
+    2023-11-21 09:36:30,626 INFO: no action. I am (coord1), the leader with the lock
+    2023-11-21 09:36:38,250 INFO: no action. I am (coord1), the leader with the lock
+    ...
+
+    $ docker exec -ti demo-haproxy bash
+    postgres@haproxy:~$ etcdctl member list
+    2b28411e74c0c281, started, etcd3, http://etcd3:2380, http://172.30.0.4:2379
+    6c70137d27cfa6c1, started, etcd2, http://etcd2:2380, http://172.30.0.5:2379
+    a28f9a70ebf21304, started, etcd1, http://etcd1:2380, http://172.30.0.6:2379
+
+    postgres@haproxy:~$ etcdctl get --keys-only --prefix /service/demo
+    /service/demo/0/config
+    /service/demo/0/initialize
+    /service/demo/0/leader
+    /service/demo/0/members/coord1
+    /service/demo/0/members/coord2
+    /service/demo/0/members/coord3
+    /service/demo/0/status
+    /service/demo/0/sync
+    /service/demo/1/config
+    /service/demo/1/initialize
+    /service/demo/1/leader
+    /service/demo/1/members/work1-1
+    /service/demo/1/members/work1-2
+    /service/demo/1/status
+    /service/demo/1/sync
+    /service/demo/2/config
+    /service/demo/2/initialize
+    /service/demo/2/leader
+    /service/demo/2/members/work2-1
+    /service/demo/2/members/work2-2
+    /service/demo/2/status
+    /service/demo/2/sync
+
+    postgres@haproxy:~$ psql -h localhost -p 5000 -U postgres -d citus
+    Password for user postgres: postgres
+    psql (15.5 (Debian 15.5-1.pgdg120+1))
+    SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, compression: off)
+    Type "help" for help.
+
+    citus=# select pg_is_in_recovery();
+     pg_is_in_recovery
+    -------------------
+     f
+    (1 row)
+
+    citus=# table pg_dist_node;
+     nodeid | groupid |  nodename  | nodeport | noderack | hasmetadata | isactive | noderole | nodecluster | metadatasynced | shouldhaveshards 
+    --------+---------+------------+----------+----------+-------------+----------+----------+-------------+----------------+------------------
+          1 |       0 | 172.30.0.3 |     5432 | default  | t           | t        | primary  | default     | t              | f
+          2 |       1 | 172.30.0.7 |     5432 | default  | t           | t        | primary  | default     | t              | t
+          3 |       2 | 172.30.0.8 |     5432 | default  | t           | t        | primary  | default     | t              | t
+    (3 rows)
+
+    citus=# \q
+
+    postgres@haproxy:~$ patronictl list
+    + Citus cluster: demo ----------+--------------+-----------+----+-----------+
+    | Group | Member  | Host        | Role         | State     | TL | Lag in MB |
+    +-------+---------+-------------+--------------+-----------+----+-----------+
+    |     0 | coord1  | 172.30.0.3  | Leader       | running   |  1 |           |
+    |     0 | coord2  | 172.30.0.12 | Replica      | streaming |  1 |         0 |
+    |     0 | coord3  | 172.30.0.2  | Sync Standby | streaming |  1 |         0 |
+    |     1 | work1-1 | 172.30.0.7  | Leader       | running   |  1 |           |
+    |     1 | work1-2 | 172.30.0.10 | Sync Standby | streaming |  1 |         0 |
+    |     2 | work2-1 | 172.30.0.8  | Leader       | running   |  1 |           |
+    |     2 | work2-2 | 172.30.0.11 | Sync Standby | streaming |  1 |         0 |
+    +-------+---------+-------------+--------------+-----------+----+-----------+
+
+
+    postgres@haproxy:~$ patronictl switchover --group 2 --force
+    Current cluster topology
+    + Citus cluster: demo (group: 2, 7303846899271086103) --+-----------+
+    | Member  | Host        | Role         | State     | TL | Lag in MB |
+    +---------+-------------+--------------+-----------+----+-----------+
+    | work2-1 | 172.30.0.8  | Leader       | running   |  1 |           |
+    | work2-2 | 172.30.0.11 | Sync Standby | streaming |  1 |         0 |
+    +---------+-------------+--------------+-----------+----+-----------+
+    2023-11-21 09:44:15.83849 Successfully switched over to "work2-2"
+    + Citus cluster: demo (group: 2, 7303846899271086103) -------+
+    | Member  | Host        | Role    | State   | TL | Lag in MB |
+    +---------+-------------+---------+---------+----+-----------+
+    | work2-1 | 172.30.0.8  | Replica | stopped |    |   unknown |
+    | work2-2 | 172.30.0.11 | Leader  | running |  1 |           |
+    +---------+-------------+---------+---------+----+-----------+
+
+    postgres@haproxy:~$ patronictl list
+    + Citus cluster: demo ----------+--------------+-----------+----+-----------+
+    | Group | Member  | Host        | Role         | State     | TL | Lag in MB |
+    +-------+---------+-------------+--------------+-----------+----+-----------+
+    |     0 | coord1  | 172.30.0.3  | Leader       | running   |  1 |           |
+    |     0 | coord2  | 172.30.0.12 | Replica      | streaming |  1 |         0 |
+    |     0 | coord3  | 172.30.0.2  | Sync Standby | streaming |  1 |         0 |
+    |     1 | work1-1 | 172.30.0.7  | Leader       | running   |  1 |           |
+    |     1 | work1-2 | 172.30.0.10 | Sync Standby | streaming |  1 |         0 |
+    |     2 | work2-1 | 172.30.0.8  | Sync Standby | streaming |  2 |         0 |
+    |     2 | work2-2 | 172.30.0.11 | Leader       | running   |  2 |           |
+    +-------+---------+-------------+--------------+-----------+----+-----------+
+
+    postgres@haproxy:~$ psql -h localhost -p 5000 -U postgres -d citus
+    psql (15.5 (Debian 15.5-1.pgdg120+1))
+    SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, compression: off)
+    Type "help" for help.
+
+    citus=# table pg_dist_node;
+     nodeid | groupid |  nodename   | nodeport | noderack | hasmetadata | isactive | noderole | nodecluster | metadatasynced | shouldhaveshards 
+    --------+---------+-------------+----------+----------+-------------+----------+----------+-------------+----------------+------------------
+          1 |       0 | 172.30.0.3  |     5432 | default  | t           | t        | primary  | default     | t              | f
+          3 |       2 | 172.30.0.11 |     5432 | default  | t           | t        | primary  | default     | t              | t
+          2 |       1 | 172.30.0.7  |     5432 | default  | t           | t        | primary  | default     | t              | t
+    (3 rows)

docker/entrypoint.sh

@@ -7,29 +7,38 @@ if [ -f /a.tar.xz ]; then
     sudo ln -snf dash /bin/sh
 fi
 
-readonly PATRONI_SCOPE=${PATRONI_SCOPE:-batman}
-PATRONI_NAMESPACE=${PATRONI_NAMESPACE:-/service}
-readonly PATRONI_NAMESPACE=${PATRONI_NAMESPACE%/}
-readonly DOCKER_IP=$(hostname --ip-address)
+readonly PATRONI_SCOPE="${PATRONI_SCOPE:-batman}"
+PATRONI_NAMESPACE="${PATRONI_NAMESPACE:-/service}"
+readonly PATRONI_NAMESPACE="${PATRONI_NAMESPACE%/}"
+DOCKER_IP=$(hostname --ip-address)
+readonly DOCKER_IP
+
+export DUMB_INIT_SETSID=0
 
 case "$1" in
     haproxy)
         haproxy -f /etc/haproxy/haproxy.cfg -p /var/run/haproxy.pid -D
-        CONFD="confd -prefix=$PATRONI_NAMESPACE/$PATRONI_SCOPE -interval=10 -backend"
-        if [ ! -z "$PATRONI_ZOOKEEPER_HOSTS" ]; then
-            while ! /usr/share/zookeeper/bin/zkCli.sh -server $PATRONI_ZOOKEEPER_HOSTS ls /; do
+        set -- confd "-prefix=$PATRONI_NAMESPACE/$PATRONI_SCOPE" -interval=10 -backend
+        if [ -n "$PATRONI_ZOOKEEPER_HOSTS" ]; then
+            while ! /usr/share/zookeeper/bin/zkCli.sh -server "$PATRONI_ZOOKEEPER_HOSTS" ls /; do
                 sleep 1
             done
-            exec dumb-init $CONFD zookeeper -node $PATRONI_ZOOKEEPER_HOSTS
+            set -- "$@" zookeeper -node "$PATRONI_ZOOKEEPER_HOSTS"
         else
-            while ! etcdctl cluster-health 2> /dev/null; do
+            while ! etcdctl member list 2> /dev/null; do
                 sleep 1
             done
-            exec dumb-init $CONFD etcdv3 -node $(echo $ETCDCTL_ENDPOINTS | sed 's/,/ -node /g')
+            set -- "$@" etcdv3
+            while IFS='' read -r line; do
+                set -- "$@" -node "$line"
+            done <<-EOT
+$(echo "$ETCDCTL_ENDPOINTS" | sed 's/,/\n/g')
+EOT
         fi
+        exec dumb-init "$@"
         ;;
     etcd)
-        exec "$@" -advertise-client-urls http://$DOCKER_IP:2379
+        exec "$@" -advertise-client-urls "http://$DOCKER_IP:2379"
         ;;
     zookeeper)
         exec /usr/share/zookeeper/bin/zkServer.sh start-foreground
@@ -56,5 +65,13 @@ export PATRONI_REPLICATION_USERNAME="${PATRONI_REPLICATION_USERNAME:-replicator}
 export PATRONI_REPLICATION_PASSWORD="${PATRONI_REPLICATION_PASSWORD:-replicate}"
 export PATRONI_SUPERUSER_USERNAME="${PATRONI_SUPERUSER_USERNAME:-postgres}"
 export PATRONI_SUPERUSER_PASSWORD="${PATRONI_SUPERUSER_PASSWORD:-postgres}"
+export PATRONI_REPLICATION_SSLMODE="${PATRONI_REPLICATION_SSLMODE:-$PGSSLMODE}"
+export PATRONI_REPLICATION_SSLKEY="${PATRONI_REPLICATION_SSLKEY:-$PGSSLKEY}"
+export PATRONI_REPLICATION_SSLCERT="${PATRONI_REPLICATION_SSLCERT:-$PGSSLCERT}"
+export PATRONI_REPLICATION_SSLROOTCERT="${PATRONI_REPLICATION_SSLROOTCERT:-$PGSSLROOTCERT}"
+export PATRONI_SUPERUSER_SSLMODE="${PATRONI_SUPERUSER_SSLMODE:-$PGSSLMODE}"
+export PATRONI_SUPERUSER_SSLKEY="${PATRONI_SUPERUSER_SSLKEY:-$PGSSLKEY}"
+export PATRONI_SUPERUSER_SSLCERT="${PATRONI_SUPERUSER_SSLCERT:-$PGSSLCERT}"
+export PATRONI_SUPERUSER_SSLROOTCERT="${PATRONI_SUPERUSER_SSLROOTCERT:-$PGSSLROOTCERT}"
 
-exec python3 /patroni.py postgres0.yml
+exec dumb-init python3 /patroni.py postgres0.yml

docs/CONTRIBUTING.rst

@@ -1,62 +1,12 @@
 .. _contributing:
 
-Contributing guidelines
-=======================
+Contributing
+============
 
-Wanna contribute to Patroni? Yay - here is how!
+Resources and information for developers can be found in the pages below.
 
-Chatting
---------
+.. toctree::
+   :maxdepth: 2
 
-Just want to chat with other Patroni users?  Looking for interactive troubleshooting help? Join us on channel #patroni in the `PostgreSQL Slack <https://postgres-slack.herokuapp.com/>`__.
-
-Running tests
--------------
-
-Requirements for running behave tests:
-
-1. PostgreSQL packages need to be installed.
-2. PostgreSQL binaries must be available in your `PATH`. You may need to add them to the path with something like `PATH=/usr/lib/postgresql/11/bin:$PATH python -m behave`.
-3. If you'd like to test with external DCSs (e.g., Etcd, Consul, and Zookeeper) you'll need the packages installed and respective services running and accepting unencrypted/unprotected connections on localhost and default port. In the case of Etcd or Consul, the behave test suite could start them up if binaries are available in the `PATH`.
-
- Install dependencies:
-
-.. code-block:: bash
-
-    # You may want to use Virtualenv or specify pip3.
-    pip install -r requirements.txt
-    pip install -r requirements.dev.txt
-
-After you have all dependencies installed, you can run the various test suites:
-
-.. code-block:: bash
-
-    # You may want to use Virtualenv or specify python3.
-
-    # Run flake8 to check syntax and formatting:
-    python setup.py flake8
-
-    # Run the pytest suite in tests/:
-    python setup.py test
-
-    # Run the behave (https://behave.readthedocs.io/en/latest/) test suite in features/;
-    # modify DCS as desired (raft has no dependencies so is the easiest to start with):
-    DCS=raft python -m behave
-
-Reporting issues
-----------------
-
-If you have a question about patroni or have a problem using it, please read the :ref:`README <readme>` before filing an issue.
-Also double check with the current issues on our `Issues Tracker <https://github.com/zalando/patroni/issues>`__.
-
-Contributing a pull request
----------------------------
-
-1) Submit a comment to the relevant issue or create a new issue describing your proposed change.
-2) Do a fork, develop and test your code changes.
-3) Include documentation
-4) Submit a pull request.
-
-You'll get feedback about your pull request as soon as possible.
-
-Happy Patroni hacking ;-)
+   contributing_guidelines
+   Patroni API docs<modules/modules>

docs/ENVIRONMENT.rst

@@ -14,24 +14,30 @@ Global/Universal
 
 Log
 ---
+-  **PATRONI\_LOG\_TYPE**: sets the format of logs. Can be either **plain** or **json**. To use **json** format, you must have the :ref:`jsonlogger <extras>` installed. The default value is **plain**.
 -  **PATRONI\_LOG\_LEVEL**: sets the general logging level. Default value is **INFO** (see `the docs for Python logging <https://docs.python.org/3.6/library/logging.html#levels>`_)
 -  **PATRONI\_LOG\_TRACEBACK\_LEVEL**: sets the level where tracebacks will be visible. Default value is **ERROR**. Set it to **DEBUG** if you want to see tracebacks only if you enable **PATRONI\_LOG\_LEVEL=DEBUG**.
--  **PATRONI\_LOG\_FORMAT**: sets the log formatting string. Default value is **%(asctime)s %(levelname)s: %(message)s** (see `the LogRecord attributes <https://docs.python.org/3.6/library/logging.html#logrecord-attributes>`_)
+-  **PATRONI\_LOG\_FORMAT**: sets the log formatting string. If the log type is **plain**, the log format should be a string.
+   Refer to `the LogRecord attributes <https://docs.python.org/3.6/library/logging.html#logrecord-attributes>`_ for
+   available attributes. If the log type is **json**, the log format can be a list in addition to a string. Each list
+   item should correspond to LogRecord attributes. Be cautious that only the field name is required, and the **%(**
+   and **)** should be omitted. If you wish to print a log field with a different key name, use a dictionary where
+   the dictionary key is the log field, and the value is the name of the field you want to be printed in the log.
+   Default value is **%(asctime)s %(levelname)s: %(message)s**
 -  **PATRONI\_LOG\_DATEFORMAT**: sets the datetime formatting string. (see the `formatTime() documentation <https://docs.python.org/3.6/library/logging.html#logging.Formatter.formatTime>`_)
+-  **PATRONI\_LOG\_STATIC\_FIELDS**: add additional fields to the log. This option is only available when the log type is set to **json**. Example ``PATRONI_LOG_STATIC_FIELDS="{app: patroni}"``
 -  **PATRONI\_LOG\_MAX\_QUEUE\_SIZE**: Patroni is using two-step logging. Log records are written into the in-memory queue and there is a separate thread which pulls them from the queue and writes to stderr or file. The maximum size of the internal queue is limited by default by **1000** records, which is enough to keep logs for the past 1h20m.
 -  **PATRONI\_LOG\_DIR**: Directory to write application logs to. The directory must exist and be writable by the user executing Patroni. If you set this env variable, the application will retain 4 25MB logs by default. You can tune those retention values with `PATRONI_LOG_FILE_NUM` and `PATRONI_LOG_FILE_SIZE` (see below).
 -  **PATRONI\_LOG\_FILE\_NUM**: The number of application logs to retain.
 -  **PATRONI\_LOG\_FILE\_SIZE**: Size of patroni.log file (in bytes) that triggers a log rolling.
 -  **PATRONI\_LOG\_LOGGERS**: Redefine logging level per python module. Example ``PATRONI_LOG_LOGGERS="{patroni.postmaster: WARNING, urllib3: DEBUG}"``
 
-Bootstrap configuration
------------------------
-It is possible to create new database users right after the successful initialization of a new cluster. This process is defined by the following variables:
+Citus
+-----
+Enables integration Patroni with `Citus <https://docs.citusdata.com>`__. If configured, Patroni will take care of registering Citus worker nodes on the coordinator. You can find more information about Citus support :ref:`here <citus>`.
 
--  **PATRONI\_<username>\_PASSWORD='<password>'**
--  **PATRONI\_<username>\_OPTIONS='list,of,options'**
-
-Example: defining ``PATRONI_admin_PASSWORD=strongpasswd`` and ``PATRONI_admin_OPTIONS='createrole,createdb'`` will cause creation of the user **admin** with the password **strongpasswd** that is allowed to create other users and databases.
+-  **PATRONI\_CITUS\_GROUP**: the Citus group id, integer. Use ``0`` for coordinator and ``1``, ``2``, etc... for workers
+-  **PATRONI\_CITUS\_DATABASE**: the database where ``citus`` extension should be created. Must be the same on the coordinator and all workers. Currently only one database is supported.
 
 Consul
 ------
@@ -47,7 +53,8 @@ Consul
 -  **PATRONI\_CONSUL\_DC**: (optional) Datacenter to communicate with. By default the datacenter of the host is used.
 -  **PATRONI\_CONSUL\_CONSISTENCY**: (optional) Select consul consistency mode. Possible values are ``default``, ``consistent``, or ``stale`` (more details in `consul API reference <https://www.consul.io/api/features/consistency.html/>`__)
 -  **PATRONI\_CONSUL\_CHECKS**: (optional) list of Consul health checks used for the session. By default an empty list is used.
--  **PATRONI\_CONSUL\_REGISTER\_SERVICE**: (optional) whether or not to register a service with the name defined by the scope parameter and the tag master, replica or standby-leader depending on the node's role. Defaults to **false**
+-  **PATRONI\_CONSUL\_REGISTER\_SERVICE**: (optional) whether or not to register a service with the name defined by the scope parameter and the tag master, primary, replica, or standby-leader depending on the node's role. Defaults to **false**
+-  **PATRONI\_CONSUL\_SERVICE\_TAGS**: (optional) additional static tags to add to the Consul service apart from the role (``master``/``primary``/``replica``/``standby-leader``). By default an empty list is used.
 -  **PATRONI\_CONSUL\_SERVICE\_CHECK\_INTERVAL**: (optional) how often to perform health check against registered url
 -  **PATRONI\_CONSUL\_SERVICE\_CHECK\_TLS\_SERVER\_NAME**: (optional) overide SNI host when connecting via TLS, see also `consul agent check API reference <https://www.consul.io/api-docs/agent/check#tlsservername>`__.
 
@@ -86,6 +93,7 @@ ZooKeeper
 -  **PATRONI\_ZOOKEEPER\_KEY\_PASSWORD**: (optional) The client key password.
 -  **PATRONI\_ZOOKEEPER\_VERIFY**: (optional) Whether to verify certificate or not. Defaults to ``true``.
 -  **PATRONI\_ZOOKEEPER\_SET\_ACLS**: (optional) If set, configure Kazoo to apply a default ACL to each ZNode that it creates. ACLs will assume 'x509' schema and should be specified as a dictionary with the principal as the key and one or more permissions as a list in the value.  Permissions may be one of ``CREATE``, ``READ``, ``WRITE``, ``DELETE`` or ``ADMIN``.  For example, ``set_acls: {CN=principal1: [CREATE, READ], CN=principal2: [ALL]}``.
+-  **PATRONI\_ZOOKEEPER\_AUTH\_DATA**: (optional) Authentication credentials to use for the connection. Should be a dictionary in the form that `scheme` is the key and `credential` is the value. Defaults to empty dictionary.
 
 .. note::
     It is required to install ``kazoo>=2.6.0`` to support SSL.
@@ -104,14 +112,19 @@ Kubernetes
 -  **PATRONI\_KUBERNETES\_NAMESPACE**: (optional) Kubernetes namespace where the Patroni pod is running. Default value is `default`.
 -  **PATRONI\_KUBERNETES\_LABELS**: Labels in format ``{label1: value1, label2: value2}``. These labels will be used to find existing objects (Pods and either Endpoints or ConfigMaps) associated with the current cluster. Also Patroni will set them on every object (Endpoint or ConfigMap) it creates.
 -  **PATRONI\_KUBERNETES\_SCOPE\_LABEL**: (optional) name of the label containing cluster name. Default value is `cluster-name`.
--  **PATRONI\_KUBERNETES\_ROLE\_LABEL**: (optional) name of the label containing Postgres role (`master` or `replica`). Patroni will set this label on the pod it is running in. Default value is `role`.
+-  **PATRONI\_KUBERNETES\_ROLE\_LABEL**: (optional) name of the label containing role (master or replica or other custom value). Patroni will set this label on the pod it runs in. Default value is ``role``.
+-  **PATRONI\_KUBERNETES\_LEADER\_LABEL\_VALUE**: (optional) value of the pod label when Postgres role is `master`. Default value is `master`.
+-  **PATRONI\_KUBERNETES\_FOLLOWER\_LABEL\_VALUE**: (optional) value of the pod label when Postgres role is `replica`. Default value is `replica`.
+-  **PATRONI\_KUBERNETES\_STANDBY\_LEADER\_LABEL\_VALUE**: (optional) value of the pod label when Postgres role is ``standby_leader``. Default value is ``master``.
+-  **PATRONI\_KUBERNETES\_TMP\_ROLE\_LABEL**: (optional) name of the temporary label containing role (master or replica). Value of this label will always use the default of corresponding role. Set only when necessary.
 -  **PATRONI\_KUBERNETES\_USE\_ENDPOINTS**: (optional) if set to true, Patroni will use Endpoints instead of ConfigMaps to run leader elections and keep cluster state.
 -  **PATRONI\_KUBERNETES\_POD\_IP**: (optional) IP address of the pod Patroni is running in. This value is required when `PATRONI_KUBERNETES_USE_ENDPOINTS` is enabled and is used to populate the leader endpoint subsets when the pod's PostgreSQL is promoted.
 -  **PATRONI\_KUBERNETES\_PORTS**: (optional) if the Service object has the name for the port, the same name must appear in the Endpoint object, otherwise service won't work. For example, if your service is defined as ``{Kind: Service, spec: {ports: [{name: postgresql, port: 5432, targetPort: 5432}]}}``, then you have to set ``PATRONI_KUBERNETES_PORTS='[{"name": "postgresql", "port": 5432}]'`` and Patroni will use it for updating subsets of the leader Endpoint. This parameter is used only if `PATRONI_KUBERNETES_USE_ENDPOINTS` is set.
 -  **PATRONI\_KUBERNETES\_CACERT**: (optional) Specifies the file with the CA_BUNDLE file with certificates of trusted CAs to use while verifying Kubernetes API SSL certs. If not provided, patroni will use the value provided by the ServiceAccount secret.
+-  **PATRONI\_RETRIABLE\_HTTP\_CODES**: (optional) list of HTTP status codes from K8s API to retry on. By default Patroni is retrying on ``500``, ``503``, and ``504``, or if K8s API response has ``retry-after`` HTTP header.
 
-Raft
-----
+Raft (deprecated)
+-----------------
 
 -  **PATRONI\_RAFT\_SELF\_ADDR**: ``ip:port`` to listen on for Raft connections. The ``self_addr`` must be accessible from other nodes of the cluster. If not set, the node will not participate in consensus.
 -  **PATRONI\_RAFT\_BIND\_ADDR**: (optional) ``ip:port`` to listen on for Raft connections. If not specified the ``self_addr`` will be used.
@@ -126,7 +139,14 @@ PostgreSQL
 -  **PATRONI\_POSTGRESQL\_PROXY\_ADDRESS**: IP address + port through which a connection pool (e.g. pgbouncer) running next to Postgres is accessible. The value is written to the member key in DCS as ``proxy_url`` and could be used/useful for service discovery.
 -  **PATRONI\_POSTGRESQL\_DATA\_DIR**: The location of the Postgres data directory, either existing or to be initialized by Patroni.
 -  **PATRONI\_POSTGRESQL\_CONFIG\_DIR**: The location of the Postgres configuration directory, defaults to the data directory. Must be writable by Patroni.
--  **PATRONI\_POSTGRESQL\_BIN_DIR**: Path to PostgreSQL binaries. (pg_ctl, pg_rewind, pg_basebackup, postgres) The  default value is an empty string meaning that PATH environment variable will be used to find the executables.
+-  **PATRONI\_POSTGRESQL\_BIN_DIR**: Path to PostgreSQL binaries. (pg_ctl, initdb, pg_controldata, pg_basebackup, postgres, pg_isready, pg_rewind) The  default value is an empty string meaning that PATH environment variable will be used to find the executables.
+-  **PATRONI\_POSTGRESQL\_BIN\_PG\_CTL**: (optional) Custom name for ``pg_ctl`` binary.
+-  **PATRONI\_POSTGRESQL\_BIN\_INITDB**: (optional) Custom name for ``initdb`` binary.
+-  **PATRONI\_POSTGRESQL\_BIN\_PG\_CONTROLDATA**: (optional) Custom name for ``pg_controldata`` binary.
+-  **PATRONI\_POSTGRESQL\_BIN\_PG\_BASEBACKUP**: (optional) Custom name for ``pg_basebackup`` binary.
+-  **PATRONI\_POSTGRESQL\_BIN\_POSTGRES**: (optional) Custom name for ``postgres`` binary.
+-  **PATRONI\_POSTGRESQL\_BIN\_IS\_READY**: (optional) Custom name for ``pg_isready`` binary.
+-  **PATRONI\_POSTGRESQL\_BIN\_PG\_REWIND**: (optional) Custom name for ``pg_rewind`` binary.
 -  **PATRONI\_POSTGRESQL\_PGPASS**: path to the `.pgpass <https://www.postgresql.org/docs/current/static/libpq-pgpass.html>`__ password file. Patroni creates this file before executing pg\_basebackup and under some other circumstances. The location must be writable by Patroni.
 -  **PATRONI\_REPLICATION\_USERNAME**: replication username; the user will be created during initialization. Replicas will use this user to access the replication source via streaming replication
 -  **PATRONI\_REPLICATION\_PASSWORD**: replication password; the user will be created during initialization.
@@ -150,8 +170,8 @@ PostgreSQL
 -  **PATRONI\_SUPERUSER\_SSLCRLDIR**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
 -  **PATRONI\_SUPERUSER\_GSSENCMODE**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
 -  **PATRONI\_SUPERUSER\_CHANNEL\_BINDING**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
--  **PATRONI\_REWIND\_USERNAME**: name for the user for ``pg_rewind``; the user will be created during initialization of postgres 11+ and all necessary `permissions <https://www.postgresql.org/docs/11/app-pgrewind.html#id-1.9.5.8.8>`__ will be granted.
--  **PATRONI\_REWIND\_PASSWORD**: password for the user for ``pg_rewind``; the user will be created during initialization.
+-  **PATRONI\_REWIND\_USERNAME**: (optional) name for the user for ``pg_rewind``; the user will be created during initialization of postgres 11+ and all necessary `permissions <https://www.postgresql.org/docs/11/app-pgrewind.html#id-1.9.5.8.8>`__ will be granted.
+-  **PATRONI\_REWIND\_PASSWORD**: (optional) password for the user for ``pg_rewind``; the user will be created during initialization.
 -  **PATRONI\_REWIND\_SSLMODE**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
 -  **PATRONI\_REWIND\_SSLKEY**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
 -  **PATRONI\_REWIND\_SSLPASSWORD**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``PATRONI_REWIND_SSLKEY``.
@@ -178,11 +198,21 @@ REST API
 -  **PATRONI\_RESTAPI\_ALLOWLIST\_INCLUDE\_MEMBERS**: (optional): If set to ``true`` it allows accessing unsafe REST API endpoints from other cluster members registered in DCS (IP address or hostname is taken from the members ``api_url``). Be careful, it might happen that OS will use a different IP for outgoing connections.
 -  **PATRONI\_RESTAPI\_HTTP\_EXTRA\_HEADERS**: (optional) HTTP headers let the REST API server pass additional information with an HTTP response.
 -  **PATRONI\_RESTAPI\_HTTPS\_EXTRA\_HEADERS**: (optional) HTTPS headers let the REST API server pass additional information with an HTTP response when TLS is enabled. This will also pass additional information set in ``http_extra_headers``.
+-  **PATRONI\_RESTAPI\_REQUEST\_QUEUE\_SIZE**: (optional): Sets request queue size for TCP socket used by Patroni REST API.  Once the queue is full, further requests get a "Connection denied" error. The default value is 5.
+
+.. warning::
+
+    - The ``PATRONI_RESTAPI_CONNECT_ADDRESS`` must be accessible from all nodes of a given Patroni cluster. Internally Patroni is using it during the leader race to find nodes with minimal replication lag.
+    - If you enabled client certificates validation (``PATRONI_RESTAPI_VERIFY_CLIENT`` is set to ``required``), you also **must** provide **valid client certificates** in the ``PATRONI_CTL_CERTFILE``, ``PATRONI_CTL_KEYFILE``, ``PATRONI_CTL_KEYFILE_PASSWORD``. If not provided, Patroni will not work correctly.
+
 
 CTL
 ---
--  **PATRONICTL\_CONFIG\_FILE**: location of the configuration file.
--  **PATRONI\_CTL\_INSECURE**: Allow connections to REST API without verifying SSL certs.
--  **PATRONI\_CTL\_CACERT**: Specifies the file with the CA_BUNDLE file or directory with certificates of trusted CAs to use while verifying REST API SSL certs. If not provided patronictl will use the value provided for REST API "cafile" parameter.
--  **PATRONI\_CTL\_CERTFILE**: Specifies the file with the client certificate in the PEM format. If not provided patronictl will use the value provided for REST API "certfile" parameter.
--  **PATRONI\_CTL\_KEYFILE**: Specifies the file with the client secret key in the PEM format. If not provided patronictl will use the value provided for REST API "keyfile" parameter.
+-  **PATRONICTL\_CONFIG\_FILE**: (optional) location of the configuration file.
+-  **PATRONI\_CTL\_USERNAME**: (optional) Basic-auth username for accessing protected REST API endpoints. If not provided :ref:`patronictl` will use the value provided for REST API "username" parameter.
+-  **PATRONI\_CTL\_PASSWORD**: (optional) Basic-auth password for accessing protected REST API endpoints. If not provided :ref:`patronictl` will use the value provided for REST API "password" parameter.
+-  **PATRONI\_CTL\_INSECURE**: (optional) Allow connections to REST API without verifying SSL certs.
+-  **PATRONI\_CTL\_CACERT**: (optional) Specifies the file with the CA_BUNDLE file or directory with certificates of trusted CAs to use while verifying REST API SSL certs. If not provided :ref:`patronictl` will use the value provided for REST API "cafile" parameter.
+-  **PATRONI\_CTL\_CERTFILE**: (optional) Specifies the file with the client certificate in the PEM format.
+-  **PATRONI\_CTL\_KEYFILE**: (optional) Specifies the file with the client secret key in the PEM format.
+-  **PATRONI\_CTL\_KEYFILE\_PASSWORD**: (optional) Specifies a password for decrypting the client keyfile.

docs/README.rst

@@ -4,7 +4,7 @@
 Introduction
 ============
 
-Patroni originated as a fork of `Governor <https://github.com/compose/governor>`__, the project from Compose. It includes plenty of new features.
+Patroni is a template for high availability (HA) PostgreSQL solutions using Python. Patroni originated as a fork of `Governor <https://github.com/compose/governor>`__, the project from Compose. It includes plenty of new features.
 
 For an example of a Docker-based deployment with Patroni, see `Spilo <https://github.com/zalando/spilo>`__, currently in use at Zalando.
 
@@ -25,83 +25,7 @@ We report new releases information :ref:`here <releases>`.
 Technical Requirements/Installation
 -----------------------------------
 
-**Pre-requirements for Mac OS**
-
-To install requirements on a Mac, run the following:
-
-::
-
-    brew install postgresql etcd haproxy libyaml python
-
-.. _psycopg2_install_options:
-
-**Psycopg**
-
-Starting from `psycopg2-2.8 <http://initd.org/psycopg/articles/2019/04/04/psycopg-28-released/>`__ the binary version of psycopg2 will no longer be installed by default. Installing it from the source code requires C compiler and postgres+python dev packages.
-Since in the python world it is not possible to specify dependency as ``psycopg2 OR psycopg2-binary`` you will have to decide how to install it.
-
-There are a few options available:
-
-1. Use the package manager from your distro
-
-::
-
-    sudo apt-get install python-psycopg2   # install python2 psycopg2 module on Debian/Ubuntu
-    sudo apt-get install python3-psycopg2  # install python3 psycopg2 module on Debian/Ubuntu
-    sudo yum install python-psycopg2       # install python2 psycopg2 on RedHat/Fedora/CentOS
-
-2. Install psycopg2 from the binary package
-
-::
-
-    pip install psycopg2-binary
-
-3. Install psycopg2 from source
-
-::
-
-    pip install psycopg2>=2.5.4
-
-4. Use psycopg 3.0 instead of psycopg2
-
-::
-
-    pip install psycopg[binary]>=3.0.0
-
-**General installation for pip**
-
-Patroni can be installed with pip:
-
-::
-
-    pip install patroni[dependencies]
-
-where dependencies can be either empty, or consist of one or more of the following:
-
-etcd or etcd3
-    `python-etcd` module in order to use Etcd as Distributed Configuration Store (DCS)
-consul
-    `python-consul` module in order to use Consul as DCS
-zookeeper
-    `kazoo` module in order to use Zookeeper as DCS
-exhibitor
-    `kazoo` module in order to use Exhibitor as DCS (same dependencies as for Zookeeper)
-kubernetes
-    `kubernetes` module in order to use Kubernetes as DCS in Patroni
-raft
-    `pysyncobj` module in order to use python Raft implementation as DCS
-aws
-    `boto` in order to use AWS callbacks
-
-For example, the command in order to install Patroni together with dependencies for Etcd as a DCS and AWS callbacks is:
-
-::
-
-    pip install patroni[etcd,aws]
-
-Note that external tools to call in the replica creation or custom bootstrap scripts (i.e. WAL-E) should be installed
-independently of Patroni.
-
+Go :ref:`here <installation>` for guidance on installing and upgrading Patroni on various platforms.
 
 .. _running_configuring:
 
@@ -109,7 +33,7 @@ Planning the Number of PostgreSQL Nodes
 ---------------------------------------
 
 Patroni/PostgreSQL nodes are decoupled from DCS nodes (except when Patroni implements RAFT on its own) and therefore
-there is no requirement on the minimal number of nodes. Running a cluster consisting of one primary and one standby is 
+there is no requirement on the minimal number of nodes. Running a cluster consisting of one primary and one standby is
 perfectly fine. You can add more standby nodes later.
 
 Running and Configuring
@@ -145,7 +69,7 @@ run:
 YAML Configuration
 ------------------
 
-Go :ref:`here <settings>` for comprehensive information about settings for etcd, consul, and ZooKeeper. And for an example, see `postgres0.yml <https://github.com/zalando/patroni/blob/master/postgres0.yml>`__.
+Go :ref:`here <yaml_configuration>` for comprehensive information about settings for etcd, consul, and ZooKeeper. And for an example, see `postgres0.yml <https://github.com/zalando/patroni/blob/master/postgres0.yml>`__.
 
 
 Environment Configuration
@@ -165,10 +89,6 @@ Applications Should Not Use Superusers
 
 When connecting from an application, always use a non-superuser. Patroni requires access to the database to function properly. By using a superuser from an application, you can potentially use the entire connection pool, including the connections reserved for superusers, with the ``superuser_reserved_connections`` setting. If Patroni cannot access the Primary because the connection pool is full, behavior will be undesirable.
 
-.. |Build Status| image:: https://travis-ci.org/zalando/patroni.svg?branch=master
-   :target: https://travis-ci.org/zalando/patroni
-.. |Coverage Status| image:: https://coveralls.io/repos/zalando/patroni/badge.svg?branch=master
-   :target: https://coveralls.io/r/zalando/patroni?branch=master
 
 Testing Your HA Solution
 --------------------------------------
@@ -177,9 +97,9 @@ Testing an HA solution is a time consuming process, with many variables. This is
 That said, here are some pieces of your infrastructure you should be sure to test:
 
 * Network (the network in front of your system as well as the NICs [physical or virtual] themselves)
-* Disk IO 
+* Disk IO
 * file limits (nofile in Linux)
-* RAM. Even if you have oomkiller turned off as suggested, the unavailability of RAM could cause issues.
+* RAM. Even if you have oomkiller turned off, the unavailability of RAM could cause issues.
 * CPU
 * Virtualization Contention (overcommitting the hypervisor)
 * Any cgroup limitation (likely to be related to the above)

docs/SETTINGS.rst

@@ -1,397 +0,0 @@
-.. _settings:
-
-===========================
-YAML Configuration Settings
-===========================
-
-.. _dynamic_configuration_settings:
-
-Dynamic configuration settings
-------------------------------
-
-Dynamic configuration is stored in the DCS (Distributed Configuration Store) and applied on all cluster nodes. Some parameters, like **loop_wait**, **ttl**, **postgresql.parameters.max_connections**, **postgresql.parameters.max_worker_processes** and so on could be set only in the dynamic configuration. Some other parameters like **postgresql.listen**, **postgresql.data_dir** could be set only locally, i.e. in the Patroni config file or via :ref:`configuration <environment>` variable. In most cases the local configuration will override the dynamic configuration. In order to change the dynamic configuration you can use either ``patronictl edit-config`` tool or Patroni :ref:`REST API <rest_api>`.
-
--  **loop\_wait**: the number of seconds the loop will sleep. Default value: 10
--  **ttl**: the TTL to acquire the leader lock (in seconds). Think of it as the length of time before initiation of the automatic failover process. Default value: 30
--  **retry\_timeout**: timeout for DCS and PostgreSQL operation retries (in seconds). DCS or network issues shorter than this will not cause Patroni to demote the leader. Default value: 10
--  **maximum\_lag\_on\_failover**: the maximum bytes a follower may lag to be able to participate in leader election.
--  **maximum\_lag\_on\_syncnode**: the maximum bytes a synchronous follower may lag before it is considered as an unhealthy candidate and swapped by healthy asynchronous follower. Patroni utilize the max replica lsn if there is more than one follower, otherwise it will use leader's current wal lsn. Default is -1, Patroni will not take action to swap synchronous unhealthy follower when the value is set to 0 or below. Please set the value high enough so Patroni won't swap synchrounous follower fequently during high transaction volume.
--  **max\_timelines\_history**: maximum number of timeline history items kept in DCS.  Default value: 0. When set to 0, it keeps the full history in DCS.
--  **master\_start\_timeout**: the amount of time a primary is allowed to recover from failures before failover is triggered (in seconds). Default is 300 seconds. When set to 0 failover is done immediately after a crash is detected if possible. When using asynchronous replication a failover can cause lost transactions. Worst case failover time for primary failure is: loop\_wait + master\_start\_timeout + loop\_wait, unless master\_start\_timeout is zero, in which case it's just loop\_wait. Set the value according to your durability/availability tradeoff.
-- **master\_stop\_timeout**: The number of seconds Patroni is allowed to wait when stopping Postgres and effective only when synchronous_mode is enabled. When set to > 0 and the synchronous_mode is enabled, Patroni sends SIGKILL to the postmaster if the stop operation is running for more than the value set by master_stop_timeout. Set the value according to your durability/availability tradeoff. If the parameter is not set or set <= 0, master_stop_timeout does not apply.
--  **synchronous\_mode**: turns on synchronous replication mode. In this mode a replica will be chosen as synchronous and only the latest leader and synchronous replica are able to participate in leader election. Synchronous mode makes sure that successfully committed transactions will not be lost at failover, at the cost of losing availability for writes when Patroni cannot ensure transaction durability. See :ref:`replication modes documentation <replication_modes>` for details.
--  **synchronous\_mode\_strict**: prevents disabling synchronous replication if no synchronous replicas are available, blocking all client writes to the primary. See :ref:`replication modes documentation <replication_modes>` for details.
--  **postgresql**:
-    -  **use\_pg\_rewind**: whether or not to use pg_rewind. Defaults to `false`.
-    -  **use\_slots**: whether or not to use replication slots. Defaults to `true` on PostgreSQL 9.4+.
-    -  **recovery\_conf**: additional configuration settings written to recovery.conf when configuring follower. There is no recovery.conf anymore in PostgreSQL 12, but you may continue using this section, because Patroni handles it transparently.
-    -  **parameters**: list of configuration settings for Postgres.
--  **standby\_cluster**: if this section is defined, we want to bootstrap a standby cluster.
-    -  **host**: an address of remote node
-    -  **port**: a port of remote node
-    -  **primary\_slot\_name**: which slot on the remote node to use for replication. This parameter is optional, the default value is derived from the instance name (see function `slot_name_from_member_name`).
-    -  **create\_replica\_methods**: an ordered list of methods that can be used to bootstrap standby leader from the remote primary, can be different from the list defined in :ref:`postgresql_settings`
-    -  **restore\_command**: command to restore WAL records from the remote primary to nodes in a standby cluster, can be different from the list defined in :ref:`postgresql_settings`
-    -  **archive\_cleanup\_command**: cleanup command for standby leader
-    -  **recovery\_min\_apply\_delay**: how long to wait before actually apply WAL records on a standby leader
--  **slots**: define permanent replication slots. These slots will be preserved during switchover/failover. The logical slots are copied from the primary to a standby with restart, and after that their position advanced every **loop_wait** seconds (if necessary). Copying logical slot files performed via ``libpq`` connection and using either rewind or superuser credentials (see **postgresql.authentication** section). There is always a chance that the logical slot position on the replica is a bit behind the former primary, therefore application should be prepared that some messages could be received the second time after the failover. The easiest way of doing so - tracking ``confirmed_flush_lsn``. Enabling permanent logical replication slots requires **postgresql.use_slots** to be set and will also automatically enable the ``hot_standby_feedback``. Since the failover of logical replication slots is unsafe on PostgreSQL 9.6 and older and PostgreSQL version 10 is missing some important functions, the feature only works with PostgreSQL 11+.
-    -  **my_slot_name**: the name of replication slot. If the permanent slot name matches with the name of the current primary it will not be created. Everything else is the responsibility of the operator to make sure that there are no clashes in names between replication slots automatically created by Patroni for members and permanent replication slots.
-        -  **type**: slot type. Could be ``physical`` or ``logical``. If the slot is logical, you have to additionally define ``database`` and ``plugin``.
-        -  **database**: the database name where logical slots should be created.
-        -  **plugin**: the plugin name for the logical slot.
--  **ignore_slots**: list of sets of replication slot properties for which Patroni should ignore matching slots. This configuration/feature/etc. is useful when some replication slots are managed outside of Patroni. Any subset of matching properties will cause a slot to be ignored.
-    -  **name**: the name of the replication slot.
-    -  **type**: slot type. Can be ``physical`` or ``logical``. If the slot is logical, you may additionally define ``database`` and/or ``plugin``.
-    -  **database**: the database name (when matching a ``logical`` slot).
-    -  **plugin**: the logical decoding plugin (when matching a ``logical`` slot).
-
-Note: **slots** is a hashmap while **ignore_slots** is an array. For example:
-
-.. code:: YAML
-
-        slots:
-          permanent_logical_slot_name:
-            type: logical
-            database: my_db
-            plugin: test_decoding
-          permanent_physical_slot_name:
-            type: physical
-          ...
-        ignore_slots:
-          - name: ignored_logical_slot_name
-            type: logical
-            database: my_db
-            plugin: test_decoding
-          - name: ignored_physical_slot_name
-            type: physical
-          ...
-
-Global/Universal
-----------------
--  **name**: the name of the host. Must be unique for the cluster.
--  **namespace**: path within the configuration store where Patroni will keep information about the cluster. Default value: "/service"
--  **scope**: cluster name
-
-Log
----
--  **level**: sets the general logging level. Default value is **INFO** (see `the docs for Python logging <https://docs.python.org/3.6/library/logging.html#levels>`_)
--  **traceback\_level**: sets the level where tracebacks will be visible. Default value is **ERROR**. Set it to **DEBUG** if you want to see tracebacks only if you enable **log.level=DEBUG**.
--  **format**: sets the log formatting string. Default value is **%(asctime)s %(levelname)s: %(message)s** (see `the LogRecord attributes <https://docs.python.org/3.6/library/logging.html#logrecord-attributes>`_)
--  **dateformat**: sets the datetime formatting string. (see the `formatTime() documentation <https://docs.python.org/3.6/library/logging.html#logging.Formatter.formatTime>`_)
--  **max\_queue\_size**: Patroni is using two-step logging. Log records are written into the in-memory queue and there is a separate thread which pulls them from the queue and writes to stderr or file. The maximum size of the internal queue is limited by default by **1000** records, which is enough to keep logs for the past 1h20m.
--  **dir**: Directory to write application logs to. The directory must exist and be writable by the user executing Patroni. If you set this value, the application will retain 4 25MB logs by default. You can tune those retention values with `file_num` and `file_size` (see below).
--  **file\_num**: The number of application logs to retain.
--  **file\_size**: Size of patroni.log file (in bytes) that triggers a log rolling.
--  **loggers**: This section allows redefining logging level per python module
-    -  **patroni.postmaster: WARNING**
-    -  **urllib3: DEBUG**
-
-.. _bootstrap_settings:
-
-Bootstrap configuration
------------------------
--  **bootstrap**:
-    -  **dcs**: This section will be written into `/<namespace>/<scope>/config` of the given configuration store after initializing of new cluster. The global dynamic configuration for the cluster. Under the ``bootstrap.dcs`` you can put any of the parameters described in the :ref:`Dynamic Configuration settings <dynamic_configuration_settings>` and after Patroni initialized (bootstrapped) the new cluster, it will write this section into `/<namespace>/<scope>/config` of the configuration store. All later changes of ``bootstrap.dcs`` will not take any effect! If you want to change them please use either ``patronictl edit-config`` or Patroni :ref:`REST API <rest_api>`.
-    -  **method**: custom script to use for bootstrapping this cluster.
-       See :ref:`custom bootstrap methods documentation <custom_bootstrap>` for details.
-       When ``initdb`` is specified revert to the default ``initdb`` command. ``initdb`` is also triggered when no ``method``
-       parameter is present in the configuration file.
-    -  **initdb**: List options to be passed on to initdb.
-            -  **- data-checksums**: Must be enabled when pg_rewind is needed on 9.3.
-            -  **- encoding: UTF8**: default encoding for new databases.
-            -  **- locale: UTF8**: default locale for new databases.
-    -  **pg\_hba**: list of lines that you should add to pg\_hba.conf.
-            -  **- host all all 0.0.0.0/0 md5**.
-            -  **- host replication replicator 127.0.0.1/32 md5**: A line like this is required for replication.
-    -  **users**: Some additional users which need to be created after initializing new cluster
-        -  **admin**: the name of user
-            -  **password: zalando**:
-            -  **options**: list of options for CREATE USER statement
-                -  **- createrole**
-                -  **- createdb**
-    -  **post\_bootstrap** or **post\_init**: An additional script that will be executed after initializing the cluster. The script receives a connection string URL (with the cluster superuser as a user name). The PGPASSFILE variable is set to the location of pgpass file.
-
-.. _consul_settings:
-
-Consul
-------
-Most of the parameters are optional, but you have to specify one of the **host** or **url**
-
--  **host**: the host:port for the Consul local agent.
--  **url**: url for the Consul local agent, in format: http(s)://host:port.
--  **port**: (optional) Consul port.
--  **scheme**: (optional) **http** or **https**, defaults to **http**.
--  **token**: (optional) ACL token.
--  **verify**: (optional) whether to verify the SSL certificate for HTTPS requests.
--  **cacert**: (optional) The ca certificate. If present it will enable validation.
--  **cert**: (optional) file with the client certificate.
--  **key**: (optional) file with the client key. Can be empty if the key is part of **cert**.
--  **dc**: (optional) Datacenter to communicate with. By default the datacenter of the host is used.
--  **consistency**: (optional) Select consul consistency mode. Possible values are ``default``, ``consistent``, or ``stale`` (more details in `consul API reference <https://www.consul.io/api/features/consistency.html/>`__)
--  **checks**: (optional) list of Consul health checks used for the session. By default an empty list is used.
--  **register\_service**: (optional) whether or not to register a service with the name defined by the scope parameter and the tag master, replica or standby-leader depending on the node's role. Defaults to **false**.
--  **service\_tags**: (optional) additional static tags to add to the Consul service apart from the role (``master``/``replica``/``standby-leader``).  By default an empty list is used.
--  **service\_check\_interval**: (optional) how often to perform health check against registered url. Defaults to '5s'.
--  **service\_check\_tls\_server\_name**: (optional) overide SNI host when connecting via TLS, see also `consul agent check API reference <https://www.consul.io/api-docs/agent/check#tlsservername>`__.
-
-The ``token`` needs to have the following ACL permissions:
-
-::
-
-    service_prefix "${scope}" {
-        policy = "write"
-    }
-    key_prefix "${namespace}/${scope}" {
-        policy = "write"
-    }
-    session_prefix "" {
-        policy = "write"
-    }
-
-Etcd
-----
-Most of the parameters are optional, but you have to specify one of the **host**, **hosts**, **url**, **proxy** or **srv**
-
--  **host**: the host:port for the etcd endpoint.
--  **hosts**: list of etcd endpoint in format host1:port1,host2:port2,etc... Could be a comma separated string or an actual yaml list.
--  **use\_proxies**: If this parameter is set to true, Patroni will consider **hosts** as a list of proxies and will not perform a topology discovery of etcd cluster.
--  **url**: url for the etcd.
--  **proxy**: proxy url for the etcd. If you are connecting to the etcd using proxy, use this parameter instead of **url**.
--  **srv**: Domain to search the SRV record(s) for cluster autodiscovery. Patroni will try to query these SRV service names for specified domain (in that order until first success): ``_etcd-client-ssl``, ``_etcd-client``, ``_etcd-ssl``, ``_etcd``, ``_etcd-server-ssl``, ``_etcd-server``. If SRV records for ``_etcd-server-ssl`` or ``_etcd-server`` are retrieved then ETCD peer protocol is used do query ETCD for available members. Otherwise hosts from SRV records will be used.
--  **srv\_suffix**: Configures a suffix to the SRV name that is queried during discovery. Use this flag to differentiate between multiple etcd clusters under the same domain. Works only with conjunction with **srv**. For example, if ``srv_suffix: foo`` and ``srv: example.org`` are set, the following DNS SRV query is made:``_etcd-client-ssl-foo._tcp.example.com`` (and so on for every possible ETCD SRV service name).
--  **protocol**: (optional) http or https, if not specified http is used. If the **url** or **proxy** is specified - will take protocol from them.
--  **username**: (optional) username for etcd authentication.
--  **password**: (optional) password for etcd authentication.
--  **cacert**: (optional) The ca certificate. If present it will enable validation.
--  **cert**: (optional) file with the client certificate.
--  **key**: (optional) file with the client key. Can be empty if the key is part of **cert**.
-
-Etcdv3
-------
-If you want that Patroni works with Etcd cluster via protocol version 3, you need to use the ``etcd3`` section in the Patroni configuration file. All configuration parameters are the same as for ``etcd``.
-
-.. warning::
-    Keys created with protocol version 2 are not visible with protocol version 3 and the other way around, therefore it is not possible to switch from ``etcd`` to ``etcd3`` just by updating Patroni config file.
-
-
-ZooKeeper
-----------
--  **hosts**: List of ZooKeeper cluster members in format: ['host1:port1', 'host2:port2', 'etc...'].
--  **use_ssl**: (optional) Whether SSL is used or not. Defaults to ``false``. If set to ``false``, all SSL specific parameters are ignored.
--  **cacert**: (optional) The CA certificate. If present it will enable validation.
--  **cert**: (optional) File with the client certificate.
--  **key**: (optional) File with the client key.
--  **key_password**: (optional) The client key password.
--  **verify**: (optional) Whether to verify certificate or not. Defaults to ``true``.
--  **set_acls**: (optional) If set, configure Kazoo to apply a default ACL to each ZNode that it creates. ACLs will assume 'x509' schema and should be specified as a dictionary with the principal as the key and one or more permissions as a list in the value.  Permissions may be one of ``CREATE``, ``READ``, ``WRITE``, ``DELETE`` or ``ADMIN``.  For example, ``set_acls: {CN=principal1: [CREATE, READ], CN=principal2: [ALL]}``. 
-
-.. note::
-    It is required to install ``kazoo>=2.6.0`` to support SSL.
-
-
-Exhibitor
----------
--  **hosts**: initial list of Exhibitor (ZooKeeper) nodes in format: 'host1,host2,etc...'. This list updates automatically whenever the Exhibitor (ZooKeeper) cluster topology changes.
--  **poll\_interval**: how often the list of ZooKeeper and Exhibitor nodes should be updated from Exhibitor.
--  **port**: Exhibitor port.
-
-.. _kubernetes_settings:
-
-Kubernetes
-----------
--  **bypass\_api\_service**: (optional) When communicating with the Kubernetes API, Patroni is usually relying on the `kubernetes` service, the address of which is exposed in the pods via the `KUBERNETES_SERVICE_HOST` environment variable. If `bypass_api_service` is set to ``true``, Patroni will resolve the list of API nodes behind the service and connect directly to them.
--  **namespace**: (optional) Kubernetes namespace where Patroni pod is running. Default value is `default`.
--  **labels**: Labels in format ``{label1: value1, label2: value2}``. These labels will be used to find existing objects (Pods and either Endpoints or ConfigMaps) associated with the current cluster. Also Patroni will set them on every object (Endpoint or ConfigMap) it creates.
--  **scope\_label**: (optional) name of the label containing cluster name. Default value is `cluster-name`.
--  **role\_label**: (optional) name of the label containing role (master or replica). Patroni will set this label on the pod it runs in. Default value is ``role``.
--  **use\_endpoints**: (optional) if set to true, Patroni will use Endpoints instead of ConfigMaps to run leader elections and keep cluster state.
--  **pod\_ip**: (optional) IP address of the pod Patroni is running in. This value is required when `use_endpoints` is enabled and is used to populate the leader endpoint subsets when the pod's PostgreSQL is promoted.
--  **ports**: (optional) if the Service object has the name for the port, the same name must appear in the Endpoint object, otherwise service won't work. For example, if your service is defined as ``{Kind: Service, spec: {ports: [{name: postgresql, port: 5432, targetPort: 5432}]}}``, then you have to set ``kubernetes.ports: [{"name": "postgresql", "port": 5432}]`` and Patroni will use it for updating subsets of the leader Endpoint. This parameter is used only if `kubernetes.use_endpoints` is set.
--  **cacert**: (optional) Specifies the file with the CA_BUNDLE file with certificates of trusted CAs to use while verifying Kubernetes API SSL certs. If not provided, patroni will use the value provided by the ServiceAccount secret.
-
-
-.. _raft_settings:
-
-Raft
-----
--  **self\_addr**: ``ip:port`` to listen on for Raft connections. The ``self_addr`` must be accessible from other nodes of the cluster. If not set, the node will not participate in consensus.
--  **bind\_addr**: (optional) ``ip:port`` to listen on for Raft connections. If not specified the ``self_addr`` will be used.
--  **partner\_addrs**: list of other Patroni nodes in the cluster in format: ['ip1:port', 'ip2:port', 'etc...']
--  **data\_dir**: directory where to store Raft log and snapshot. If not specified the current working directory is used.
--  **password**: (optional) Encrypt Raft traffic with a specified password, requires ``cryptography`` python module.
-
-  Short FAQ about Raft implementation
-
-  - Q: How to list all the nodes providing consensus?
-
-    A: ``syncobj_admin -conn host:port -status`` where the host:port is the address of one of the cluster nodes
-
-  - Q: Node that was a part of consensus and has gone and I can't reuse the same IP for other node. How to remove this node from the consensus?
-
-    A: ``syncobj_admin -conn host:port -remove host2:port2`` where the ``host2:port2`` is the address of the node you want to remove from consensus.
-
-  - Q: Where to get the ``syncobj_admin`` utility?
-
-    A: It is installed together with ``pysyncobj`` module (python RAFT implementation), which is Patroni dependency.
-
-  - Q: it is possible to run Patroni node without adding in to the consensus?
-
-    A: Yes, just comment out or remove ``raft.self_addr`` from Patroni configuration.
-
-  - Q: It is possible to run Patroni and PostgreSQL only on two nodes?
-
-    A: Yes, on the third node you can run ``patroni_raft_controller`` (without Patroni and PostgreSQL). In such a setup, one can temporarily lose one node without affecting the primary.
-
-
-.. _postgresql_settings:
-
-PostgreSQL
-----------
--  **postgresql**:
-    -  **authentication**:
-        -  **superuser**:
-            -  **username**: name for the superuser, set during initialization (initdb) and later used by Patroni to connect to the postgres.
-            -  **password**: password for the superuser, set during initialization (initdb).
-            -  **sslmode**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
-            -  **sslkey**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
-            -  **sslpassword**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``sslkey``.
-            -  **sslcert**: (optional) maps to the `sslcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCERT>`__ connection parameter, which specifies the location of the client certificate.
-            -  **sslrootcert**: (optional) maps to the `sslrootcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLROOTCERT>`__ connection parameter, which specifies the location of a file containing one ore more certificate authorities (CA) certificates that the client will use to verify a server's certificate.
-            -  **sslcrl**: (optional) maps to the `sslcrl <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRL>`__ connection parameter, which specifies the location of a file containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
-            -  **sslcrldir**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
-            -  **gssencmode**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
-            -  **channel_binding**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
-        -  **replication**:
-            -  **username**: replication username; the user will be created during initialization. Replicas will use this user to access the replication source via streaming replication
-            -  **password**: replication password; the user will be created during initialization.
-            -  **sslmode**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
-            -  **sslkey**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
-            -  **sslpassword**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``sslkey``.
-            -  **sslcert**: (optional) maps to the `sslcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCERT>`__ connection parameter, which specifies the location of the client certificate.
-            -  **sslrootcert**: (optional) maps to the `sslrootcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLROOTCERT>`__ connection parameter, which specifies the location of a file containing one ore more certificate authorities (CA) certificates that the client will use to verify a server's certificate.
-            -  **sslcrl**: (optional) maps to the `sslcrl <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRL>`__ connection parameter, which specifies the location of a file containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
-            -  **sslcrldir**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
-            -  **gssencmode**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
-            -  **channel_binding**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
-        -  **rewind**:
-            -  **username**: name for the user for ``pg_rewind``; the user will be created during initialization of postgres 11+ and all necessary `permissions <https://www.postgresql.org/docs/11/app-pgrewind.html#id-1.9.5.8.8>`__ will be granted.
-            -  **password**: password for the user for ``pg_rewind``; the user will be created during initialization.
-            -  **sslmode**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
-            -  **sslkey**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
-            -  **sslpassword**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``sslkey``.
-            -  **sslcert**: (optional) maps to the `sslcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCERT>`__ connection parameter, which specifies the location of the client certificate.
-            -  **sslrootcert**: (optional) maps to the `sslrootcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLROOTCERT>`__ connection parameter, which specifies the location of a file containing one ore more certificate authorities (CA) certificates that the client will use to verify a server's certificate.
-            -  **sslcrl**: (optional) maps to the `sslcrl <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRL>`__ connection parameter, which specifies the location of a file containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
-            -  **sslcrldir**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
-            -  **gssencmode**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
-            -  **channel_binding**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
-    -  **callbacks**: callback scripts to run on certain actions. Patroni will pass the action, role and cluster name. (See scripts/aws.py as an example of how to write them.)
-            -  **on\_reload**: run this script when configuration reload is triggered.
-            -  **on\_restart**: run this script when the postgres restarts (without changing role).
-            -  **on\_role\_change**: run this script when the postgres is being promoted or demoted.
-            -  **on\_start**: run this script when the postgres starts.
-            -  **on\_stop**: run this script when the postgres stops.
-    -  **connect\_address**: IP address + port through which Postgres is accessible from other nodes and applications.
-    -  **proxy\_address**: IP address + port through which a connection pool (e.g. pgbouncer) running next to Postgres is accessible. The value is written to the member key in DCS as ``proxy_url`` and could be used/useful for service discovery.
-    -  **create\_replica\_methods**: an ordered list of the create methods for turning a Patroni node into a new replica.
-       "basebackup" is the default method; other methods are assumed to refer to scripts, each of which is configured as its
-       own config item. See :ref:`custom replica creation methods documentation <custom_replica_creation>` for further explanation.
-    -  **data\_dir**: The location of the Postgres data directory, either :ref:`existing <existing_data>` or to be initialized by Patroni.
-    -  **config\_dir**: The location of the Postgres configuration directory, defaults to the data directory. Must be writable by Patroni.
-    -  **bin\_dir**: Path to PostgreSQL binaries (pg_ctl, pg_rewind, pg_basebackup, postgres). The default value is an empty string meaning that PATH environment variable will be used to find the executables.
-    -  **listen**: IP address + port that Postgres listens to; must be accessible from other nodes in the cluster, if you're using streaming replication. Multiple comma-separated addresses are permitted, as long as the port component is appended after to the last one with a colon, i.e. ``listen: 127.0.0.1,127.0.0.2:5432``. Patroni will use the first address from this list to establish local connections to the PostgreSQL node.
-    -  **use\_unix\_socket**: specifies that Patroni should prefer to use unix sockets to connect to the cluster. Default value is ``false``. If ``unix_socket_directories`` is defined, Patroni will use the first suitable value from it to connect to the cluster and fallback to tcp if nothing is suitable. If ``unix_socket_directories`` is not specified in ``postgresql.parameters``, Patroni will assume that the default value should be used and omit ``host`` from the connection parameters.
-    -  **use\_unix\_socket\_repl**: specifies that Patroni should prefer to use unix sockets for replication user cluster connection. Default value is ``false``. If ``unix_socket_directories`` is defined, Patroni will use the first suitable value from it to connect to the cluster and fallback to tcp if nothing is suitable. If ``unix_socket_directories`` is not specified in ``postgresql.parameters``, Patroni will assume that the default value should be used and omit ``host`` from the connection parameters.
-    -  **pgpass**: path to the `.pgpass <https://www.postgresql.org/docs/current/static/libpq-pgpass.html>`__ password file. Patroni creates this file before executing pg\_basebackup, the post_init script and under some other circumstances. The location must be writable by Patroni.
-    -  **recovery\_conf**: additional configuration settings written to recovery.conf when configuring follower.
-    -  **custom\_conf** : path to an optional custom ``postgresql.conf`` file, that will be used in place of ``postgresql.base.conf``. The file must exist on all cluster nodes, be readable by PostgreSQL and will be included from its location on the real ``postgresql.conf``. Note that Patroni will not monitor this file for changes, nor backup it. However, its settings can still be overridden by Patroni's own configuration facilities - see :ref:`dynamic configuration <dynamic_configuration>` for details.
-    -  **parameters**: list of configuration settings for Postgres. Many of these are required for replication to work.
-    -  **pg\_hba**: list of lines that Patroni will use to generate ``pg_hba.conf``. This parameter has higher priority than ``bootstrap.pg_hba``. Together with :ref:`dynamic configuration <dynamic_configuration>` it simplifies management of ``pg_hba.conf``.
-            -  **- host all all 0.0.0.0/0 md5**.
-            -  **- host replication replicator 127.0.0.1/32 md5**: A line like this is required for replication.
-    -  **pg\_ident**: list of lines that Patroni will use to generate ``pg_ident.conf``. Together with :ref:`dynamic configuration <dynamic_configuration>` it simplifies management of ``pg_ident.conf``.
-            -  **- mapname1 systemname1 pguser1**.
-            -  **- mapname1 systemname2 pguser2**.
-    -  **pg\_ctl\_timeout**: How long should pg_ctl wait when doing ``start``, ``stop`` or ``restart``. Default value is 60 seconds.
-    -  **use\_pg\_rewind**: try to use pg\_rewind on the former leader when it joins cluster as a replica.
-    -  **remove\_data\_directory\_on\_rewind\_failure**: If this option is enabled, Patroni will remove the PostgreSQL data directory and recreate the replica. Otherwise it will try to follow the new leader. Default value is **false**.
-    -  **remove\_data\_directory\_on\_diverged\_timelines**: Patroni will remove the PostgreSQL data directory and recreate the replica if it notices that timelines are diverging and the former primary can not start streaming from the new primary. This option is useful when ``pg_rewind`` can not be used. While performing timelines divergence check on PostgreSQL v10 and older Patroni will try to connect with replication credential to the "postgres" database. Hence, such access should be allowed in the  pg_hba.conf. Default value is **false**.
-    -  **replica\_method**: for each create_replica_methods other than basebackup, you would add a configuration section of the same name. At a minimum, this should include "command" with a full path to the actual script to be executed. Other configuration parameters will be passed along to the script in the form "parameter=value".
-    -  **pre\_promote**: a fencing script that executes during a failover after acquiring the leader lock but before promoting the replica. If the script exits with a non-zero code, Patroni does not promote the replica and removes the leader key from DCS.
-
-REST API
---------
--  **restapi**:
-        -  **connect\_address**: IP address (or hostname) and port, to access the Patroni's :ref:`REST API <rest_api>`. All the members of the cluster must be able to connect to this address, so unless the Patroni setup is intended for a demo inside the localhost, this address must be a non "localhost" or loopback address (ie: "localhost" or "127.0.0.1"). It can serve as an endpoint for HTTP health checks (read below about the "listen" REST API parameter), and also for user queries (either directly or via the REST API), as well as for the health checks done by the cluster members during leader elections (for example, to determine whether the leader is still running, or if there is a node which has a WAL position that is ahead of the one doing the query; etc.) The connect_address is put in the member key in DCS, making it possible to translate the member name into the address to connect to its REST API.
-
-        -  **listen**: IP address (or hostname) and port that Patroni will listen to for the REST API - to provide also the same health checks and cluster messaging between the participating nodes, as described above. to provide health-check information for HAProxy (or any other load balancer capable of doing a HTTP "OPTION" or "GET" checks).
-
-        -  **authentication**: (optional)
-            -  **username**: Basic-auth username to protect unsafe REST API endpoints.
-            -  **password**: Basic-auth password to protect unsafe REST API endpoints.
-        -  **certfile**: (optional): Specifies the file with the certificate in the PEM format. If the certfile is not specified or is left empty, the API server will work without SSL.
-        -  **keyfile**: (optional): Specifies the file with the secret key in the PEM format.
-        -  **keyfile\_password**: (optional): Specifies a password for decrypting the keyfile.
-        -  **cafile**: (optional): Specifies the file with the CA_BUNDLE with certificates of trusted CAs to use while verifying client certs.
-        -  **ciphers**: (optional): Specifies the permitted cipher suites (e.g. "ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-GCM-SHA256:!SSLv1:!SSLv2:!SSLv3:!TLSv1:!TLSv1.1")
-        -  **verify\_client**: (optional): ``none`` (default), ``optional`` or ``required``. When ``none`` REST API will not check client certificates. When ``required`` client certificates are required for all REST API calls. When ``optional`` client certificates are required for all unsafe REST API endpoints. When ``required`` is used, then client authentication succeeds, if the certificate signature verification succeeds.  For ``optional`` the client cert will only be checked for ``PUT``, ``POST``, ``PATCH``, and ``DELETE`` requests.
-        -  **allowlist**: (optional): Specifies the set of hosts that are allowed to call unsafe REST API endpoints. The single element could be a host name, an IP address or a network address using CIDR notation. By default ``allow all`` is used. In case if ``allowlist`` or ``allowlist_include_members`` are set, anything that is not included is rejected.
-        -  **allowlist\_include\_members**: (optional): If set to ``true`` it allows accessing unsafe REST API endpoints from other cluster members registered in DCS (IP address or hostname is taken from the members ``api_url``). Be careful, it might happen that OS will use a different IP for outgoing connections.
-        -  **http\_extra\_headers**: (optional): HTTP headers let the REST API server pass additional information with an HTTP response.
-        -  **https\_extra\_headers**: (optional): HTTPS headers let the REST API server pass additional information with an HTTP response when TLS is enabled. This will also pass additional information set in ``http_extra_headers``.
-
-Here is an example of both **http_extra_headers** and **https_extra_headers**:
-
-.. code:: YAML
-
-        restapi:
-          listen: <listen>
-          connect_address: <connect_address>
-          authentication:
-            username: <username>
-            password: <password>
-          http_extra_headers:
-            'X-Frame-Options': 'SAMEORIGIN'
-            'X-XSS-Protection': '1; mode=block'
-            'X-Content-Type-Options': 'nosniff'
-          cafile: <ca file>
-          certfile: <cert>
-          keyfile: <key>
-          https_extra_headers:
-            'Strict-Transport-Security': 'max-age=31536000; includeSubDomains'
-
-.. _patronictl_settings:
-
-CTL
----
-- **ctl**: (optional)
-    -  **insecure**: Allow connections to REST API without verifying SSL certs.
-    -  **cacert**: Specifies the file with the CA_BUNDLE file or directory with certificates of trusted CAs to use while verifying REST API SSL certs. If not provided patronictl will use the value provided for REST API "cafile" parameter.
-    -  **certfile**: Specifies the file with the client certificate in the PEM format. If not provided patronictl will use the value provided for REST API "certfile" parameter.
-    -  **keyfile**: Specifies the file with the client secret key in the PEM format. If not provided patronictl will use the value provided for REST API "keyfile" parameter.
-    -  **keyfile\_password**: Specifies a password for decrypting the keyfile. If not provided patronictl will use the value provided for REST API "keyfile\_password" parameter.
-
-Watchdog
---------
-- **mode**: ``off``, ``automatic`` or ``required``. When ``off`` watchdog is disabled. When ``automatic`` watchdog will be used if available, but ignored if it is not. When ``required`` the node will not become a leader unless watchdog can be successfully enabled.
-- **device**: Path to watchdog device. Defaults to ``/dev/watchdog``.
-- **safety_margin**: Number of seconds of safety margin between watchdog triggering and leader key expiration.
-
-.. _tags_settings:
-
-Tags
-----
-- **nofailover**: ``true`` or ``false``, controls whether this node is allowed to participate in the leader race and become a leader. Defaults to ``false``
-- **clonefrom**: ``true`` or ``false``. If set to ``true`` other nodes might prefer to use this node for bootstrap (take ``pg_basebackup`` from). If there are several nodes with ``clonefrom`` tag set to ``true`` the node to bootstrap from will be chosen randomly. The default value is ``false``.
-- **noloadbalance**: ``true`` or ``false``. If set to ``true`` the node will return HTTP Status Code 503 for the ``GET /replica`` REST API health-check and therefore will be excluded from the load-balancing. Defaults to ``false``.
-- **replicatefrom**: The IP address/hostname of another replica. Used to support cascading replication.
-- **nosync**: ``true`` or ``false``. If set to ``true`` the node will never be selected as a synchronous replica.
-
-In addition to these predefined tags, you can also add your own ones:
-
-- **key1**: ``true``
-- **key2**: ``false``
-- **key3**: ``1.4``
-- **key4**: ``"RandomString"``
-
-Tags are visible in the :ref:`REST API <rest_api>` and ``patronictl list`` You can also check for an instance health using these tags. If the tag isn't defined for an instance, or if the respective value doesn't match the querying value, it will return HTTP Status Code 503.

docs/_static/multi-dc-asynchronous-replication.drawio

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docs/_static/multi-dc-synchronous-replication.drawio

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docs/citus.rst

@@ -0,0 +1,359 @@
+.. _citus:
+
+Citus support
+=============
+
+Patroni makes it extremely simple to deploy `Multi-Node Citus`__ clusters.
+
+__ https://docs.citusdata.com/en/stable/installation/multi_node.html
+
+TL;DR
+-----
+
+There are only a few simple rules you need to follow:
+
+1. `Citus <https://github.com/citusdata/citus>`__ database extension to
+   PostgreSQL must be available on all nodes.  Absolute minimum supported Citus
+   version is 10.0, but, to take all benefits from transparent switchovers and
+   restarts of workers we recommend using at least Citus 11.2.
+2. Cluster name (``scope``) must be the same for all Citus nodes!
+3. Superuser credentials must be the same on coordinator and all worker
+   nodes, and ``pg_hba.conf`` should allow superuser access between all nodes.
+4. :ref:`REST API <restapi_settings>` access should be allowed from worker
+   nodes to the coordinator. E.g., credentials should be the same and if
+   configured, client certificates from worker nodes must be accepted by the
+   coordinator.
+5. Add the following section to the ``patroni.yaml``:
+
+.. code:: YAML
+
+        citus:
+          group: X  # 0 for coordinator and 1, 2, 3, etc for workers
+          database: citus  # must be the same on all nodes
+
+
+After that you just need to start Patroni and it will handle the rest:
+
+1. ``citus`` extension will be automatically added to ``shared_preload_libraries``.
+2. If ``max_prepared_transactions`` isn't explicitly set in the global
+   :ref:`dynamic configuration <dynamic_configuration>` Patroni will
+   automatically set it to ``2*max_connections``.
+3. The ``citus.local_hostname`` GUC value will be adjusted from ``localhost`` to the
+   value that Patroni is using in order to connect to the local PostgreSQL
+   instance. The value sometimes should be different from the ``localhost``
+   because PostgreSQL might be not listening on it.
+4. The ``citus.database`` will be automatically created followed by ``CREATE EXTENSION citus``.
+5. Current superuser :ref:`credentials <postgresql_settings>` will be added to the ``pg_dist_authinfo``
+   table to allow cross-node communication. Don't forget to update them if
+   later you decide to change superuser username/password/sslcert/sslkey!
+6. The coordinator primary node will automatically discover worker primary
+   nodes and add them to the ``pg_dist_node`` table using the
+   ``citus_add_node()`` function.
+7. Patroni will also maintain ``pg_dist_node`` in case failover/switchover
+   on the coordinator or worker clusters occurs.
+
+patronictl
+----------
+
+Coordinator and worker clusters are physically different PostgreSQL/Patroni
+clusters that are just logically groupped together using the
+`Citus <https://github.com/citusdata/citus>`__ database extension to
+PostgreSQL. Therefore in most cases it is not possible to manage them as a
+single entity.
+
+It results in two major differences in :ref:`patronictl` behaviour when
+``patroni.yaml`` has the ``citus`` section comparing with the usual:
+
+1. The ``list`` and the ``topology`` by default output all members of the Citus
+   formation (coordinators and workers). The new column ``Group`` indicates
+   which Citus group they belong to.
+2. For all ``patronictl`` commands the new option is introduced, named
+   ``--group``. For some commands the default value for the group might be
+   taken from the ``patroni.yaml``. For example, :ref:`patronictl_pause` will
+   enable the maintenance mode by default for the ``group`` that is set in the
+   ``citus`` section, but for example for :ref:`patronictl_switchover` or
+   :ref:`patronictl_remove` the group must be explicitly specified.
+
+An example of :ref:`patronictl_list` output for the Citus cluster::
+
+    postgres@coord1:~$ patronictl list demo
+    + Citus cluster: demo ----------+--------------+---------+----+-----------+
+    | Group | Member  | Host        | Role         | State   | TL | Lag in MB |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+    |     0 | coord1  | 172.27.0.10 | Replica      | running |  1 |         0 |
+    |     0 | coord2  | 172.27.0.6  | Sync Standby | running |  1 |         0 |
+    |     0 | coord3  | 172.27.0.4  | Leader       | running |  1 |           |
+    |     1 | work1-1 | 172.27.0.8  | Sync Standby | running |  1 |         0 |
+    |     1 | work1-2 | 172.27.0.2  | Leader       | running |  1 |           |
+    |     2 | work2-1 | 172.27.0.5  | Sync Standby | running |  1 |         0 |
+    |     2 | work2-2 | 172.27.0.7  | Leader       | running |  1 |           |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+
+If we add the ``--group`` option, the output will change to::
+
+    postgres@coord1:~$ patronictl list demo --group 0
+    + Citus cluster: demo (group: 0, 7179854923829112860) -----------+
+    | Member | Host        | Role         | State   | TL | Lag in MB |
+    +--------+-------------+--------------+---------+----+-----------+
+    | coord1 | 172.27.0.10 | Replica      | running |  1 |         0 |
+    | coord2 | 172.27.0.6  | Sync Standby | running |  1 |         0 |
+    | coord3 | 172.27.0.4  | Leader       | running |  1 |           |
+    +--------+-------------+--------------+---------+----+-----------+
+
+    postgres@coord1:~$ patronictl list demo --group 1
+    + Citus cluster: demo (group: 1, 7179854923881963547) -----------+
+    | Member  | Host       | Role         | State   | TL | Lag in MB |
+    +---------+------------+--------------+---------+----+-----------+
+    | work1-1 | 172.27.0.8 | Sync Standby | running |  1 |         0 |
+    | work1-2 | 172.27.0.2 | Leader       | running |  1 |           |
+    +---------+------------+--------------+---------+----+-----------+
+
+Citus worker switchover
+-----------------------
+
+When a switchover is orchestrated for a Citus worker node, Citus offers the
+opportunity to make the switchover close to transparent for an application.
+Because the application connects to the coordinator, which in turn connects to
+the worker nodes, then it is possible with Citus to `pause` the SQL traffic on
+the coordinator for the shards hosted on a worker node. The switchover then
+happens while the traffic is kept on the coordinator, and resumes as soon as a
+new primary worker node is ready to accept read-write queries.
+
+An example of :ref:`patronictl_switchover` on the worker cluster::
+
+    postgres@coord1:~$ patronictl switchover demo
+    + Citus cluster: demo ----------+--------------+---------+----+-----------+
+    | Group | Member  | Host        | Role         | State   | TL | Lag in MB |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+    |     0 | coord1  | 172.27.0.10 | Replica      | running |  1 |         0 |
+    |     0 | coord2  | 172.27.0.6  | Sync Standby | running |  1 |         0 |
+    |     0 | coord3  | 172.27.0.4  | Leader       | running |  1 |           |
+    |     1 | work1-1 | 172.27.0.8  | Leader       | running |  1 |           |
+    |     1 | work1-2 | 172.27.0.2  | Sync Standby | running |  1 |         0 |
+    |     2 | work2-1 | 172.27.0.5  | Sync Standby | running |  1 |         0 |
+    |     2 | work2-2 | 172.27.0.7  | Leader       | running |  1 |           |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+    Citus group: 2
+    Primary [work2-2]:
+    Candidate ['work2-1'] []:
+    When should the switchover take place (e.g. 2022-12-22T08:02 )  [now]:
+    Current cluster topology
+    + Citus cluster: demo (group: 2, 7179854924063375386) -----------+
+    | Member  | Host       | Role         | State   | TL | Lag in MB |
+    +---------+------------+--------------+---------+----+-----------+
+    | work2-1 | 172.27.0.5 | Sync Standby | running |  1 |         0 |
+    | work2-2 | 172.27.0.7 | Leader       | running |  1 |           |
+    +---------+------------+--------------+---------+----+-----------+
+    Are you sure you want to switchover cluster demo, demoting current primary work2-2? [y/N]: y
+    2022-12-22 07:02:40.33003 Successfully switched over to "work2-1"
+    + Citus cluster: demo (group: 2, 7179854924063375386) ------+
+    | Member  | Host       | Role    | State   | TL | Lag in MB |
+    +---------+------------+---------+---------+----+-----------+
+    | work2-1 | 172.27.0.5 | Leader  | running |  1 |           |
+    | work2-2 | 172.27.0.7 | Replica | stopped |    |   unknown |
+    +---------+------------+---------+---------+----+-----------+
+
+    postgres@coord1:~$ patronictl list demo
+    + Citus cluster: demo ----------+--------------+---------+----+-----------+
+    | Group | Member  | Host        | Role         | State   | TL | Lag in MB |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+    |     0 | coord1  | 172.27.0.10 | Replica      | running |  1 |         0 |
+    |     0 | coord2  | 172.27.0.6  | Sync Standby | running |  1 |         0 |
+    |     0 | coord3  | 172.27.0.4  | Leader       | running |  1 |           |
+    |     1 | work1-1 | 172.27.0.8  | Leader       | running |  1 |           |
+    |     1 | work1-2 | 172.27.0.2  | Sync Standby | running |  1 |         0 |
+    |     2 | work2-1 | 172.27.0.5  | Leader       | running |  2 |           |
+    |     2 | work2-2 | 172.27.0.7  | Sync Standby | running |  2 |         0 |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+
+And this is how it looks on the coordinator side::
+
+    # The worker primary notifies the coordinator that it is going to execute "pg_ctl stop".
+    2022-12-22 07:02:38,636 DEBUG: query("BEGIN")
+    2022-12-22 07:02:38,636 DEBUG: query("SELECT pg_catalog.citus_update_node(3, '172.27.0.7-demoted', 5432, true, 10000)")
+    # From this moment all application traffic on the coordinator to the worker group 2 is paused.
+
+    # The future worker primary notifies the coordinator that it acquired the leader lock in DCS and about to run "pg_ctl promote".
+    2022-12-22 07:02:40,085 DEBUG: query("SELECT pg_catalog.citus_update_node(3, '172.27.0.5', 5432)")
+
+    # The new worker primary just finished promote and notifies coordinator that it is ready to accept read-write traffic.
+    2022-12-22 07:02:41,485 DEBUG: query("COMMIT")
+    # From this moment the application traffic on the coordinator to the worker group 2 is unblocked.
+
+Peek into DCS
+-------------
+
+The Citus cluster (coordinator and workers) are stored in DCS as a fleet of
+Patroni clusters logically grouped together::
+
+    /service/batman/              # scope=batman
+    /service/batman/0/            # citus.group=0, coordinator
+    /service/batman/0/initialize
+    /service/batman/0/leader
+    /service/batman/0/members/
+    /service/batman/0/members/m1
+    /service/batman/0/members/m2
+    /service/batman/1/            # citus.group=1, worker
+    /service/batman/1/initialize
+    /service/batman/1/leader
+    /service/batman/1/members/
+    /service/batman/1/members/m3
+    /service/batman/1/members/m4
+    ...
+
+Such an approach was chosen because for most DCS it becomes possible to fetch
+the entire Citus cluster with a single recursive read request. Only Citus
+coordinator nodes are reading the whole tree, because they have to discover
+worker nodes. Worker nodes are reading only the subtree for their own group and
+in some cases they could read the subtree of the coordinator group.
+
+Citus on Kubernetes
+-------------------
+
+Since Kubernetes doesn't support hierarchical structures we had to include the
+citus group to all K8s objects Patroni creates::
+
+    batman-0-leader  # the leader config map for the coordinator
+    batman-0-config  # the config map holding initialize, config, and history "keys"
+    ...
+    batman-1-leader  # the leader config map for worker group 1
+    batman-1-config
+    ...
+
+I.e., the naming pattern is: ``${scope}-${citus.group}-${type}``.
+
+All Kubernetes objects are discovered by Patroni using the `label selector`__,
+therefore all Pods with Patroni&Citus and Endpoints/ConfigMaps must have
+similar labels, and Patroni must be configured to use them using Kubernetes
+:ref:`settings <kubernetes_settings>` or :ref:`environment variables
+<kubernetes_environment>`.
+
+__ https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
+
+A couple of examples of Patroni configuration using Pods environment variables:
+
+1. for the coordinator cluster
+
+.. code:: YAML
+
+        apiVersion: v1
+        kind: Pod
+        metadata:
+          labels:
+            application: patroni
+            citus-group: "0"
+            citus-type: coordinator
+            cluster-name: citusdemo
+          name: citusdemo-0-0
+          namespace: default
+        spec:
+          containers:
+          - env:
+            - name: PATRONI_SCOPE
+              value: citusdemo
+            - name: PATRONI_NAME
+              valueFrom:
+                fieldRef:
+                  apiVersion: v1
+                  fieldPath: metadata.name
+            - name: PATRONI_KUBERNETES_POD_IP
+              valueFrom:
+                fieldRef:
+                  apiVersion: v1
+                  fieldPath: status.podIP
+            - name: PATRONI_KUBERNETES_NAMESPACE
+              valueFrom:
+                fieldRef:
+                  apiVersion: v1
+                  fieldPath: metadata.namespace
+            - name: PATRONI_KUBERNETES_LABELS
+              value: '{application: patroni}'
+            - name: PATRONI_CITUS_DATABASE
+              value: citus
+            - name: PATRONI_CITUS_GROUP
+              value: "0"
+
+2. for the worker cluster from the group 2
+
+.. code:: YAML
+
+        apiVersion: v1
+        kind: Pod
+        metadata:
+          labels:
+            application: patroni
+            citus-group: "2"
+            citus-type: worker
+            cluster-name: citusdemo
+          name: citusdemo-2-0
+          namespace: default
+        spec:
+          containers:
+          - env:
+            - name: PATRONI_SCOPE
+              value: citusdemo
+            - name: PATRONI_NAME
+              valueFrom:
+                fieldRef:
+                  apiVersion: v1
+                  fieldPath: metadata.name
+            - name: PATRONI_KUBERNETES_POD_IP
+              valueFrom:
+                fieldRef:
+                  apiVersion: v1
+                  fieldPath: status.podIP
+            - name: PATRONI_KUBERNETES_NAMESPACE
+              valueFrom:
+                fieldRef:
+                  apiVersion: v1
+                  fieldPath: metadata.namespace
+            - name: PATRONI_KUBERNETES_LABELS
+              value: '{application: patroni}'
+            - name: PATRONI_CITUS_DATABASE
+              value: citus
+            - name: PATRONI_CITUS_GROUP
+              value: "2"
+
+As you may noticed, both examples have ``citus-group`` label set. This label
+allows Patroni to identify object as belonging to a certain Citus group. In
+addition to that, there is also ``PATRONI_CITUS_GROUP`` environment variable,
+which has the same value as the ``citus-group`` label. When Patroni creates
+new Kubernetes objects ConfigMaps or Endpoints, it automatically puts the
+``citus-group: ${env.PATRONI_CITUS_GROUP}`` label on them:
+
+.. code:: YAML
+
+        apiVersion: v1
+        kind: ConfigMap
+        metadata:
+          name: citusdemo-0-leader  # Is generated as ${env.PATRONI_SCOPE}-${env.PATRONI_CITUS_GROUP}-leader
+          labels:
+            application: patroni    # Is set from the ${env.PATRONI_KUBERNETES_LABELS}
+            cluster-name: citusdemo # Is automatically set from the ${env.PATRONI_SCOPE}
+            citus-group: '0'        # Is automatically set from the ${env.PATRONI_CITUS_GROUP}
+
+You can find a complete example of Patroni deployment on Kubernetes with Citus
+support in the `kubernetes`__ folder of the Patroni repository.
+
+__ https://github.com/zalando/patroni/tree/master/kubernetes
+
+There are two important files for you:
+
+1. Dockerfile.citus
+2. citus_k8s.yaml
+
+Citus upgrades and PostgreSQL major upgrades
+--------------------------------------------
+
+First, please read about upgrading Citus version in the `documentation`__.
+There is one minor change in the process. When executing upgrade, you have to
+use :ref:`patronictl_restart` instead of ``systemctl restart`` to restart
+PostgreSQL.
+
+__ https://docs.citusdata.com/en/latest/admin_guide/upgrading_citus.html
+
+The PostgreSQL major upgrade with Citus is a bit more complex. You will have to
+combine techniques used in the Citus documentation about major upgrades and
+Patroni documentation about :ref:`PostgreSQL major upgrade<major_upgrade>`.
+Please keep in mind that Citus cluster consists of many Patroni clusters
+(coordinator and workers) and they all have to be upgraded independently.

docs/conf.py

@@ -20,10 +20,15 @@
 import os
 
 import sys
+
 sys.path.insert(0, os.path.abspath('..'))
 
 from patroni.version import __version__
 
+project_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))
+module_dir = os.path.abspath(os.path.join(project_root, 'patroni'))
+excludes = ['tests', 'setup.py', 'conf']
+
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
@@ -33,11 +38,28 @@ from patroni.version import __version__
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = ['sphinx.ext.intersphinx',
+extensions = [
+    'sphinx.ext.intersphinx',
     'sphinx.ext.todo',
     'sphinx.ext.mathjax',
     'sphinx.ext.ifconfig',
-    'sphinx.ext.viewcode']
+    # 'sphinx.ext.viewcode',
+    'sphinx_github_style',  # Generate "View on GitHub" for source code
+    'sphinxcontrib.apidoc',  # For generating module docs from code
+    'sphinx.ext.autodoc',  # For generating module docs from docstrings
+    'sphinx.ext.napoleon',  # For Google and Numpy formatted docstrings
+]
+apidoc_module_dir = module_dir
+apidoc_output_dir = 'modules'
+apidoc_excluded_paths = excludes
+apidoc_separate_modules = True
+
+# Include autodoc for all members, including private ones and the ones that are missing a docstring.
+autodoc_default_options = {
+    "members": True,
+    "undoc-members": True,
+    "private-members": True,
+}
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -70,7 +92,7 @@ release = __version__
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = 'en'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
@@ -90,10 +112,10 @@ todo_include_todos = True
 # a list of builtin themes.
 #
 
+html_theme = 'sphinx_rtd_theme'
 on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
 if not on_rtd:  # only import and set the theme if we're building docs locally
     import sphinx_rtd_theme
-    html_theme = 'sphinx_rtd_theme'
     html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
 
 # Theme options are theme-specific and customize the look and feel of a theme
@@ -107,6 +129,34 @@ if not on_rtd:  # only import and set the theme if we're building docs locally
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
+# Replace "source" links with "edit on GitHub" when using rtd theme
+html_context = {
+    'display_github': True,
+    'github_user': 'zalando',
+    'github_repo': 'patroni',
+    'github_version': 'master',
+    'conf_py_path': '/docs/',
+}
+
+# sphinx-github-style options, https://sphinx-github-style.readthedocs.io/en/latest/index.html
+
+# The name of the top-level package.
+top_level = "patroni"
+
+# The blob to link to on GitHub - any of "head", "last_tag", or "{blob}"
+# linkcode_blob = 'head'
+
+# The link to your GitHub repository formatted as https://github.com/user/repo
+# If not provided, will attempt to create the link from the html_context dict
+# linkcode_url = f"https://github.com/{html_context['github_user']}/" \
+#                f"{html_context['github_repo']}/{html_context['github_version']}"
+
+# The text to use for the linkcode link
+# linkcode_link_text: str = "View on GitHub"
+
+# A linkcode_resolve() function to use for resolving the link target
+# linkcode_resolve: types.FunctionType
+
 
 # -- Options for HTMLHelp output ------------------------------------------
 
@@ -165,7 +215,6 @@ texinfo_documents = [
 ]
 
 
-
 # -- Options for Epub output ----------------------------------------------
 
 # Bibliographic Dublin Core info.
@@ -187,9 +236,64 @@ epub_copyright = copyright
 epub_exclude_files = ['search.html']
 
 
-
 # Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {'https://docs.python.org/': None}
+intersphinx_mapping = {'python': ('https://docs.python.org/', None)}
+
+
+# Remove these pages from index, references, toc trees, etc.
+# If the builder is not 'html' then add the API docs modules index to pages to be removed.
+exclude_from_builder = {
+    'latex': ['modules/modules'],
+    'epub': ['modules/modules'],
+}
+# Internal holding list, anything added here will always be excluded
+_docs_to_remove = []
+
+
+def builder_inited(app):
+    """Run during Sphinx `builder-inited` phase.
+
+    Set a config value to builder name and add module docs to `docs_to_remove`.
+    """
+    print(f'The builder is: {app.builder.name}')
+    app.add_config_value('builder', app.builder.name, 'env')
+
+    # Remove pages when builder matches any referenced in exclude_from_builder
+    if exclude_from_builder.get(app.builder.name):
+        _docs_to_remove.extend(exclude_from_builder[app.builder.name])
+
+
+def env_get_outdated(app, env, added, changed, removed):
+    """Run during Sphinx `env-get-outdated` phase.
+
+    Remove the items listed in `docs_to_remove` from known pages.
+    """
+    added.difference_update(_docs_to_remove)
+    changed.difference_update(_docs_to_remove)
+    removed.update(_docs_to_remove)
+    return []
+
+
+def doctree_read(app, doctree):
+    """Run during Sphinx `doctree-read` phase.
+
+    Remove the items listed in `docs_to_remove` from the table of contents.
+    """
+    from sphinx import addnodes
+    for toc_tree_node in doctree.traverse(addnodes.toctree):
+        for e in toc_tree_node['entries']:
+            ref = str(e[1])
+            if ref in _docs_to_remove:
+                toc_tree_node['entries'].remove(e)
+
+
+def autodoc_skip(app, what, name, obj, would_skip, options):
+    """Include autodoc of ``__init__`` methods, which are skipped by default."""
+    if name == "__init__":
+        return False
+    return would_skip
+
+
 
 # A possibility to have an own stylesheet, to add new rules or override existing ones
 # For the latter case, the CSS specificity of the rules should be higher than the default ones
@@ -198,3 +302,9 @@ def setup(app):
         app.add_css_file('custom.css')
     else:
         app.add_stylesheet('custom.css')
+
+    # Run extra steps to remove module docs when running with a non-html builder
+    app.connect('builder-inited', builder_inited)
+    app.connect('env-get-outdated', env_get_outdated)
+    app.connect('doctree-read', doctree_read)
+    app.connect("autodoc-skip-member", autodoc_skip)

docs/contributing_guidelines.rst

@@ -0,0 +1,190 @@
+.. _contributing_guidelines:
+
+Contributing guidelines
+=======================
+
+.. _chatting:
+
+Chatting
+--------
+
+If you have a question, looking for an interactive troubleshooting help or want to chat with other Patroni users, join us on channel `#patroni <https://postgresteam.slack.com/archives/C9XPYG92A>`__ in the `PostgreSQL Slack <https://pgtreats.info/slack-invite>`__.
+
+.. _reporting_bugs:
+
+Reporting bugs
+--------------
+
+Before reporting a bug please make sure to **reproduce it with the latest Patroni version**!
+Also please double check if the issue already exists in our `Issues Tracker <https://github.com/zalando/patroni/issues>`__.
+
+Running tests
+-------------
+
+Requirements for running behave tests:
+
+#. PostgreSQL packages including `contrib <https://www.postgresql.org/docs/current/contrib.html>`__ modules need to be installed.
+#. PostgreSQL binaries must be available in your `PATH`. You may need to add them to the path with something like `PATH=/usr/lib/postgresql/11/bin:$PATH python -m behave`.
+#. If you'd like to test with external DCSs (e.g., Etcd, Consul, and Zookeeper) you'll need the packages installed and respective services running and accepting unencrypted/unprotected connections on localhost and default port. In the case of Etcd or Consul, the behave test suite could start them up if binaries are available in the `PATH`.
+
+Install dependencies:
+
+.. code-block:: bash
+
+    # You may want to use Virtualenv or specify pip3.
+    pip install -r requirements.txt
+    pip install -r requirements.dev.txt
+
+After you have all dependencies installed, you can run the various test suites:
+
+.. code-block:: bash
+
+    # You may want to use Virtualenv or specify python3.
+
+    # Run flake8 to check syntax and formatting:
+    python setup.py flake8
+
+    # Run the pytest suite in tests/:
+    python setup.py test
+
+    # Moreover, you may want to run tests in different scopes for debugging purposes,
+    # the -s option include print output during test execution.
+    # Tests in pytest typically follow the pattern: FILEPATH::CLASSNAME::TESTNAME.
+    pytest -s tests/test_api.py
+    pytest -s tests/test_api.py::TestRestApiHandler
+    pytest -s tests/test_api.py::TestRestApiHandler::test_do_GET
+
+    # Run the behave (https://behave.readthedocs.io/en/latest/) test suite in features/;
+    # modify DCS as desired (raft has no dependencies so is the easiest to start with):
+    DCS=raft python -m behave
+
+Testing with tox
+----------------
+
+To run tox tests you only need to install one dependency (other than Python)
+
+.. code-block:: bash
+
+    pip install tox>=4
+
+If you wish to run `behave` tests then you also need docker installed.
+
+Tox configuration in `tox.ini` has "environments" to run the following tasks:
+
+* lint: Python code lint with `flake8`
+* test: unit tests for all available python interpreters with `pytest`,
+  generates XML reports or HTML reports if a TTY is detected
+* dep: detect package dependency conflicts using `pipdeptree`
+* type: static type checking with `pyright`
+* black: code formatting with `black`
+* docker-build: build docker image used for the `behave` env
+* docker-cmd: run arbitrary command with the above image
+* docker-behave-etcd: run tox for behave tests with above image
+* py*behave: run behave with available python interpreters (without docker, although
+  this is what is called inside docker containers)
+* docs: build docs with `sphinx`
+
+Running tox
+^^^^^^^^^^^
+
+To run the default env list; dep, lint, test, and docs, just run:
+
+.. code-block:: bash
+
+    tox
+
+The `test` envs can be run with the label `test`:
+
+.. code-block:: bash
+
+   tox -m test
+
+The `behave` docker tests can be run with the label `behave`:
+
+.. code-block:: bash
+
+   tox -m behave
+
+Similarly, docs has the label `docs`.
+
+All other envs can be run with their respective env names:
+
+.. code-block:: bash
+
+   tox -e lint
+   tox -e py39-test-lin
+
+It is also possible to select partial env lists using `factors`. For example, if you want to run
+all envs for python 3.10:
+
+.. code-block:: bash
+
+    tox -f py310
+
+This is equivalent to running all the envs listed below:
+
+.. code-block:: bash
+
+    $ tox -l -f py310
+    py310-test-lin
+    py310-test-mac
+    py310-test-win
+    py310-type-lin
+    py310-type-mac
+    py310-type-win
+    py310-behave-etcd-lin
+    py310-behave-etcd-win
+    py310-behave-etcd-mac
+
+
+You can list all configured combinations of environments with tox (>=v4) like so
+
+.. code-block:: bash
+
+    tox l
+
+The envs `test` and `docs` will attempt to open the HTML output files
+when the job completes, if tox is run with an active terminal. This
+is intended to be for benefit of the developer running this env locally.
+It will attempt to run `open` on a mac and `xdg-open` on Linux.
+To use a different command set the env var `OPEN_CMD` to the name or path of
+the command. If this step fails it will not fail the run overall.
+If you want to disable this facility set the env var `OPEN_CMD` to the `:` no-op command.
+
+.. code-block:: bash
+
+   OPEN_CMD=: tox -m docs
+
+Behave tests
+^^^^^^^^^^^^
+
+Behave tests with `-m behave` will build docker images based on PG_MAJOR version 11 through 16 and then run all
+behave tests. This can take quite a long time to run so you might want to limit the scope to a select version of
+Postgres or to a specific feature set or steps.
+
+To specify the version of postgres include the full name of the dependent image build env that you want and then the
+behave env name. For instance if you want Postgres 14 use:
+
+.. code-block:: bash
+
+    tox -e pg14-docker-build,pg14-docker-behave-etcd-lin
+
+If on the other hand you want to test a specific feature you can pass positional arguments to behave. This will run
+the watchdog behave feature test scenario with all versions of Postgres.
+
+.. code-block:: bash
+
+    tox -m behave -- features/watchdog.feature
+
+Of course you can combine the two.
+
+Contributing a pull request
+---------------------------
+
+#. Fork the repository, develop and test your code changes.
+#. Reflect changes in the user documentation.
+#. Submit a pull request with a clear description of the changes objective. Link an existing issue if necessary.
+
+You'll get feedback about your pull request as soon as possible.
+
+Happy Patroni hacking ;-)

docs/dcs_failsafe_mode.rst

@@ -0,0 +1,63 @@
+.. _dcs_failsafe_mode:
+
+DCS Failsafe Mode
+=================
+
+The problem
+-----------
+
+Patroni is heavily relying on Distributed Configuration Store (DCS) to solve the task of leader elections and detect network partitioning. That is, the node is allowed to run Postgres as the primary only if it can update the leader lock in DCS. In case the update of the leader lock fails, Postgres is immediately demoted and started as read-only. Depending on which DCS is used, the chances of hitting the "problem" differ. For example, with Etcd which is only used for Patroni, chances are close to zero, while with K8s API (backed by Etcd) it could be observed more frequently.
+
+
+Reasons for the current implementation
+---------------------------------------
+
+The leader lock update failure could be caused by two main reasons:
+
+1. Network partitioning
+2. DCS being down
+
+In general, it is impossible to distinguish between these two from a single node, and therefore Patroni assumes the worst case - network partitioning. In the case of a partitioned network, other nodes of the Patroni cluster may successfully grab the leader lock and promote Postgres to primary. In order to avoid a split-brain, the old primary is demoted before the leader lock expires.
+
+
+DCS Failsafe Mode
+-----------------
+
+We introduce a new special option, the ``failsafe_mode``. It could be enabled only via global :ref:`dynamic configuration <dynamic_configuration>` stored in the DCS ``/config`` key. If the failsafe mode is enabled and the leader lock update in DCS failed due to reasons different from the version/value/index mismatch, Postgres may continue to run as a primary if it can access all known members of the cluster via Patroni REST API.
+
+
+Low-level implementation details
+--------------------------------
+
+- We introduce a new, permanent key in DCS, named ``/failsafe``.
+- The ``/failsafe`` key contains all known members of the given Patroni cluster at a given time.
+- The current leader maintains the ``/failsafe`` key.
+- The member is allowed to participate in the leader race and become the new leader only if it is present in the ``/failsafe`` key.
+- If the cluster consists of a single node the ``/failsafe`` key will contain a single member.
+- In the case of DCS "outage" the existing primary connects to all members presented in the ``/failsafe`` key via the ``POST /failsafe`` REST API and may continue to run as the primary if all replicas acknowledge it.
+- If one of the members doesn't respond, the primary is demoted.
+- Replicas are using incoming ``POST /failsafe`` REST API requests as an indicator that the primary is still alive. This information is cached for ``ttl`` seconds.
+
+
+F.A.Q.
+------
+
+- Why MUST the current primary see ALL other members? Can’t we rely on quorum here?
+
+  This is a great question! The problem is that the view on the quorum might be different from the perspective of DCS and Patroni. While DCS nodes must be evenly distributed across availability zones, there is no such rule for Patroni, and more importantly, there is no mechanism for introducing and enforcing such a rule. If the majority of Patroni nodes ends up in the losing part of the partitioned network (including primary) while minority nodes are in the winning part, the primary must be demoted. Only checking ALL other members allows detecting such a situation.
+
+- What if node/pod gets terminated while DCS is down?
+
+  If DCS isn’t accessible, the check “are ALL other cluster members accessible?” is executed every cycle of the heartbeat loop (every ``loop_wait`` seconds). If pod/node is terminated, the check will fail and Postgres will be demoted to a read-only and will not recover until DCS is restored.
+
+- What if all members of the Patroni cluster are lost while DCS is down?
+
+  Patroni could be configured to create the new replica from the backup even when the cluster doesn't have a leader. But, if the new member isn't present in the ``/failsafe`` key, it will not be able to grab the leader lock and promote.
+
+- What will happen if the primary lost access to DCS while replicas didn't?
+
+  The primary will execute the failsafe code and contact all known replicas. These replicas will use this information as an indicator that the primary is alive and will not start the leader race even if the leader lock in DCS has expired.
+
+- How to enable the Failsafe Mode?
+
+  Before enabling the ``failsafe_mode`` please make sure that Patroni version on all members is up-to-date. After that, you can use either the ``PATCH /config`` :ref:`REST API <rest_api>` or :ref:`patronictl edit-config -s failsafe_mode=true <patronictl_edit_config_parameters>`

docs/dynamic_configuration.rst

@@ -1,89 +1,110 @@
 .. _dynamic_configuration:
 
-Patroni configuration
-=====================
+==============================
+Dynamic Configuration Settings
+==============================
 
-Patroni configuration is stored in the DCS (Distributed Configuration Store). There are 3 types of configuration:
+Dynamic configuration is stored in the DCS (Distributed Configuration Store) and applied on all cluster nodes.
 
-- Dynamic configuration.
-	These options can be set in DCS at any time. If the options changed are not part of the startup configuration,
-	they are applied asynchronously (upon the next wake up cycle) to every node, which gets subsequently reloaded.
-	If the node requires a restart to apply the configuration (for options with context postmaster, if their values
-	have changed), a special flag, ``pending_restart`` indicating this, is set in the members.data JSON.
-	Additionally, the node status also indicates this, by showing ``"restart_pending": true``.
+In order to change the dynamic configuration you can use either :ref:`patronictl_edit_config` tool or Patroni :ref:`REST API <rest_api>`.
 
-- Local :ref:`configuration <settings>` (patroni.yml).
-	These options are defined in the configuration file and take precedence over dynamic configuration.
-	patroni.yml could be changed and reloaded in runtime (without restart of Patroni) by sending SIGHUP to the Patroni process, performing ``POST /reload`` REST-API request or executing ``patronictl reload``.
+-  **loop\_wait**: the number of seconds the loop will sleep. Default value: 10, minimum possible value: 1
+-  **ttl**: the TTL to acquire the leader lock (in seconds). Think of it as the length of time before initiation of the automatic failover process. Default value: 30, minimum possible value: 20
+-  **retry\_timeout**: timeout for DCS and PostgreSQL operation retries (in seconds). DCS or network issues shorter than this will not cause Patroni to demote the leader. Default value: 10, minimum possible value: 3
 
-- Environment :ref:`configuration <environment>`.
-	It is possible to set/override some of the "Local" configuration parameters with environment variables.
-	Environment configuration is very useful when you are running in a dynamic environment and you don't know some of the parameters in advance (for example it's not possible to know your external IP address when you are running inside ``docker``).
+.. warning::
+    when changing values of **loop_wait**, **retry_timeout**, or **ttl** you have to follow the rule:
 
-The local configuration can be either a single YAML file or a directory. When it is a directory, all YAML files in that directory are loaded one by one in sorted order. In case a key is defined in multiple files, the occurrence in the last file takes precedence.
+    .. code-block:: python
 
-Some of the PostgreSQL parameters must hold the same values on the primary and the replicas. For those, values set either in the local patroni configuration files or via the environment variables take no effect. To alter or set their values one must change the shared configuration in the DCS. Below is the actual list of such parameters together with the default values:
-
-- max_connections: 100
-- max_locks_per_transaction: 64
-- max_worker_processes: 8
-- max_prepared_transactions: 0
-- wal_level: hot_standby
-- wal_log_hints: on
-- track_commit_timestamp: off
-
-For the parameters below, PostgreSQL does not require equal values among the primary and all the replicas. However, considering the possibility of a replica to become the primary at any time, it doesn't really make sense to set them differently; therefore, Patroni restricts setting their values to the Dynamic configuration
-
-- max_wal_senders: 5
-- max_replication_slots: 5
-- wal_keep_segments: 8
-- wal_keep_size: 128MB
-
-These parameters are validated to ensure they are sane, or meet a minimum value.
-
-There are some other Postgres parameters controlled by Patroni:
-
-- listen_addresses - is set either from ``postgresql.listen`` or from ``PATRONI_POSTGRESQL_LISTEN`` environment variable
-- port - is set either from ``postgresql.listen`` or from ``PATRONI_POSTGRESQL_LISTEN`` environment variable
-- cluster_name - is set either from ``scope`` or from ``PATRONI_SCOPE`` environment variable
-- hot_standby: on
-
-To be on the safe side parameters from the above lists are not written into ``postgresql.conf``, but passed as a list of arguments to the ``pg_ctl start`` which gives them the highest precedence, even above `ALTER SYSTEM <https://www.postgresql.org/docs/current/static/sql-altersystem.html>`__
+        loop_wait + 2 * retry_timeout <= ttl
 
 
-When applying the local or dynamic configuration options, the following actions are taken:
+-  **maximum\_lag\_on\_failover**: the maximum bytes a follower may lag to be able to participate in leader election.
+-  **maximum\_lag\_on\_syncnode**: the maximum bytes a synchronous follower may lag before it is considered as an unhealthy candidate and swapped by healthy asynchronous follower. Patroni utilize the max replica lsn if there is more than one follower, otherwise it will use leader's current wal lsn. Default is -1, Patroni will not take action to swap synchronous unhealthy follower when the value is set to 0 or below. Please set the value high enough so Patroni won't swap synchrounous follower fequently during high transaction volume.
+-  **max\_timelines\_history**: maximum number of timeline history items kept in DCS.  Default value: 0. When set to 0, it keeps the full history in DCS.
+-  **primary\_start\_timeout**: the amount of time a primary is allowed to recover from failures before failover is triggered (in seconds). Default is 300 seconds. When set to 0 failover is done immediately after a crash is detected if possible. When using asynchronous replication a failover can cause lost transactions. Worst case failover time for primary failure is: loop\_wait + primary\_start\_timeout + loop\_wait, unless primary\_start\_timeout is zero, in which case it's just loop\_wait. Set the value according to your durability/availability tradeoff.
+-  **primary\_stop\_timeout**: The number of seconds Patroni is allowed to wait when stopping Postgres and effective only when synchronous_mode is enabled. When set to > 0 and the synchronous_mode is enabled, Patroni sends SIGKILL to the postmaster if the stop operation is running for more than the value set by primary\_stop\_timeout. Set the value according to your durability/availability tradeoff. If the parameter is not set or set <= 0, primary\_stop\_timeout does not apply.
+-  **synchronous\_mode**: turns on synchronous replication mode. In this mode a replica will be chosen as synchronous and only the latest leader and synchronous replica are able to participate in leader election. Synchronous mode makes sure that successfully committed transactions will not be lost at failover, at the cost of losing availability for writes when Patroni cannot ensure transaction durability. See :ref:`replication modes documentation <replication_modes>` for details.
+-  **synchronous\_mode\_strict**: prevents disabling synchronous replication if no synchronous replicas are available, blocking all client writes to the primary. See :ref:`replication modes documentation <replication_modes>` for details.
+-  **failsafe\_mode**: Enables :ref:`DCS Failsafe Mode <dcs_failsafe_mode>`. Defaults to `false`.
+-  **postgresql**:
 
-- The node first checks if there is a postgresql.base.conf or if the ``custom_conf`` parameter is set.
-- If the `custom_conf` parameter is set, it will take the file specified on it as a base configuration, ignoring `postgresql.base.conf` and `postgresql.conf`.
-- If the `custom_conf` parameter is not set and `postgresql.base.conf` exists, it contains the renamed "original" configuration and it will be used as a base configuration.
-- If there is no `custom_conf` nor `postgresql.base.conf`, the original postgresql.conf is taken and renamed to postgresql.base.conf.
-- The dynamic options (with the exceptions above) are dumped into the postgresql.conf and an include is set in
-  postgresql.conf to the used base configuration (either postgresql.base.conf or what is on ``custom_conf``). Therefore, we would be able to apply new options without re-reading the configuration file to check if the include is present not.
-- Some parameters that are essential for Patroni to manage the cluster are overridden using the command line.
-- If some of the options that require restart are changed (we should look at the context in pg_settings and at the actual
-  values of those options), a pending_restart flag of a given node is set. This flag is reset on any restart.
+   -  **use\_pg\_rewind**: whether or not to use pg_rewind. Defaults to `false`.
+   -  **use\_slots**: whether or not to use replication slots. Defaults to `true` on PostgreSQL 9.4+.
+   -  **recovery\_conf**: additional configuration settings written to recovery.conf when configuring follower. There is no recovery.conf anymore in PostgreSQL 12, but you may continue using this section, because Patroni handles it transparently.
+   -  **parameters**: list of configuration settings for Postgres.
 
-The parameters would be applied in the following order (run-time are given the highest priority):
+   -  **pg\_hba**: list of lines that Patroni will use to generate ``pg_hba.conf``. Patroni ignores this parameter if ``hba_file`` PostgreSQL parameter is set to a non-default value.
 
-1. load parameters from file `postgresql.base.conf` (or from a `custom_conf` file, if set)
-2. load parameters from file `postgresql.conf`
-3. load parameters from file `postgresql.auto.conf`
-4. run-time parameter using `-o --name=value`
+      -  **- host all all 0.0.0.0/0 md5**
+      -  **- host replication replicator 127.0.0.1/32 md5**: A line like this is required for replication.
 
-This allows configuration for all the nodes (2), configuration for a specific node using `ALTER SYSTEM` (3) and ensures that parameters essential to the running of Patroni are enforced (4), as well as leaves room for configuration tools that manage `postgresql.conf` directly without involving Patroni (1).
+   -  **pg\_ident**: list of lines that Patroni will use to generate ``pg_ident.conf``. Patroni ignores this parameter if ``ident_file`` PostgreSQL parameter is set to a non-default value.
+
+      -  **- mapname1 systemname1 pguser1**
+      -  **- mapname1 systemname2 pguser2**
+
+-  **standby\_cluster**: if this section is defined, we want to bootstrap a standby cluster.
+
+   -  **host**: an address of remote node
+   -  **port**: a port of remote node
+   -  **primary\_slot\_name**: which slot on the remote node to use for replication. This parameter is optional, the default value is derived from the instance name (see function `slot_name_from_member_name`).
+   -  **create\_replica\_methods**: an ordered list of methods that can be used to bootstrap standby leader from the remote primary, can be different from the list defined in :ref:`postgresql_settings`
+   -  **restore\_command**: command to restore WAL records from the remote primary to nodes in a standby cluster, can be different from the list defined in :ref:`postgresql_settings`
+   -  **archive\_cleanup\_command**: cleanup command for standby leader
+   -  **recovery\_min\_apply\_delay**: how long to wait before actually apply WAL records on a standby leader
+
+-  **slots**: define permanent replication slots. These slots will be preserved during switchover/failover. Permanent slots that don't exist will be created by Patroni. With PostgreSQL 11 onwards permanent physical slots are created on all nodes and their position is advanced every **loop_wait** seconds. For PostgreSQL versions older than 11 permanent physical replication slots are maintained only on the current primary. The logical slots are copied from the primary to a standby with restart, and after that their position advanced every **loop_wait** seconds (if necessary). Copying logical slot files performed via ``libpq`` connection and using either rewind or superuser credentials (see **postgresql.authentication** section). There is always a chance that the logical slot position on the replica is a bit behind the former primary, therefore application should be prepared that some messages could be received the second time after the failover. The easiest way of doing so - tracking ``confirmed_flush_lsn``. Enabling permanent replication slots requires **postgresql.use_slots** to be set to ``true``. If there are permanent logical replication slots defined Patroni will automatically enable the ``hot_standby_feedback``. Since the failover of logical replication slots is unsafe on PostgreSQL 9.6 and older and PostgreSQL version 10 is missing some important functions, the feature only works with PostgreSQL 11+.
+
+   -  **my\_slot\_name**: the name of the permanent replication slot. If the permanent slot name matches with the name of the current node it will not be created on this node. If you add a permanent physical replication slot which name matches the name of a Patroni member, Patroni will ensure that the slot that was created is not removed even if the corresponding member becomes unresponsive, situation which would normally result in the slot's removal by Patroni. Although this can be useful in some situations, such as when you want replication slots used by members to persist during temporary failures or when importing existing members to a new Patroni cluster (see :ref:`Convert a Standalone to a Patroni Cluster <existing_data>` for details), caution should be exercised by the operator that these clashes in names are not persisted in the DCS, when the slot is no longer required, due to its effect on normal functioning of Patroni.
+
+      -  **type**: slot type. Could be ``physical`` or ``logical``. If the slot is logical, you have to additionally define ``database`` and ``plugin``.
+      -  **database**: the database name where logical slots should be created.
+      -  **plugin**: the plugin name for the logical slot.
+
+-  **ignore\_slots**: list of sets of replication slot properties for which Patroni should ignore matching slots. This configuration/feature/etc. is useful when some replication slots are managed outside of Patroni. Any subset of matching properties will cause a slot to be ignored.
+
+   -  **name**: the name of the replication slot.
+   -  **type**: slot type. Can be ``physical`` or ``logical``. If the slot is logical, you may additionally define ``database`` and/or ``plugin``.
+   -  **database**: the database name (when matching a ``logical`` slot).
+   -  **plugin**: the logical decoding plugin (when matching a ``logical`` slot).
+
+Note: **slots** is a hashmap while **ignore_slots** is an array. For example:
+
+.. code:: YAML
+
+        slots:
+          permanent_logical_slot_name:
+            type: logical
+            database: my_db
+            plugin: test_decoding
+          permanent_physical_slot_name:
+            type: physical
+          ...
+        ignore_slots:
+          - name: ignored_logical_slot_name
+            type: logical
+            database: my_db
+            plugin: test_decoding
+          - name: ignored_physical_slot_name
+            type: physical
+          ...
+
+Note: if cluster topology is static (fixed number of nodes that never change their names) you can configure permanent physical replication slots with names corresponding to names of nodes to avoid recycling of WAL files while replica is temporary down:
+
+.. code:: YAML
+
+        slots:
+          node_name1:
+            type: physical
+          node_name2:
+            type: physical
+          node_name3:
+            type: physical
+          ...
 
 
-Also, the following Patroni configuration options can be changed only dynamically:
-
-- ttl: 30
-- loop_wait: 10
-- retry_timeouts: 10
-- maximum_lag_on_failover: 1048576
-- max_timelines_history: 0
-- check_timeline: false
-- postgresql.use_slots: true
-
-Upon changing these options, Patroni will read the relevant section of the configuration stored in DCS and change its
-run-time values.
-
-Patroni nodes are dumping the state of the DCS options to disk upon for every change of the configuration into the file ``patroni.dynamic.json`` located in the Postgres data directory. Only the leader is allowed to restore these options from the on-disk dump if these are completely absent from the DCS or if they are invalid.
+.. warning::
+   Permanent replication slots are synchronized only from the ``primary``/``standby_leader`` to replica nodes. That means, applications are supposed to be using them only from the leader node. Using them on replica nodes will cause indefinite growth of ``pg_wal`` on all other nodes in the cluster.
+   An exception to that rule are permanent physical slots that match the Patroni member names, if you happen to configure any. Those will be synchronized among all nodes as they are used for replication among them.

docs/existing_data.rst

@@ -10,32 +10,74 @@ To deploy a Patroni cluster without using a pre-existing PostgreSQL instance, se
 Procedure
 ---------
 
-A Patroni cluster can be started with a data directory from a single-node PostgreSQL database. This is achieved by following closely these steps:
+You can find below an overview of steps for converting an existing Postgres cluster to a Patroni managed cluster. In the steps we assume all nodes that are part of the existing cluster are currently up and running, and that you *do not* intend to change Postgres configuration while the migration is ongoing. The steps:
 
-1. Manually start PostgreSQL daemon
-2. Create Patroni superuser and replication users as defined in the :ref:`authentication <postgresql_settings>` section of the Patroni configuration. If this user is created in SQL, the following queries achieve this:
+#. Create the Postgres users as explained for :ref:`authentication <postgresql_settings>` section of the Patroni configuration. You can find sample SQL commands to create the users in the code block below, in which you need to replace the usernames and passwords as per your environment. If you already have the relevant users, then you can skip this step.
 
-.. code-block:: sql
+   .. code-block:: sql
 
-   CREATE USER $PATRONI_SUPERUSER_USERNAME WITH SUPERUSER ENCRYPTED PASSWORD '$PATRONI_SUPERUSER_PASSWORD';
-   CREATE USER $PATRONI_REPLICATION_USERNAME WITH REPLICATION ENCRYPTED PASSWORD '$PATRONI_REPLICATION_PASSWORD';
+      -- Patroni superuser
+      -- Replace PATRONI_SUPERUSER_USERNAME and PATRONI_SUPERUSER_PASSWORD accordingly
+      CREATE USER PATRONI_SUPERUSER_USERNAME WITH SUPERUSER ENCRYPTED PASSWORD 'PATRONI_SUPERUSER_PASSWORD';
 
-3. Start Patroni (e.g. ``patroni /etc/patroni/patroni.yml``). It automatically detects that PostgreSQL daemon is already running but its configuration might be out-of-date.
-4. Ask Patroni to restart the node with ``patronictl restart cluster-name node-name``. This step is only required if PostgreSQL configuration is out-of-date.
+      -- Patroni replication user
+      -- Replace PATRONI_REPLICATION_USERNAME and PATRONI_REPLICATION_PASSWORD accordingly
+      CREATE USER PATRONI_REPLICATION_USERNAME WITH REPLICATION ENCRYPTED PASSWORD 'PATRONI_REPLICATION_PASSWORD';
+
+      -- Patroni rewind user, if you intend to enable use_pg_rewind in your Patroni configuration
+      -- Replace PATRONI_REWIND_USERNAME and PATRONI_REWIND_PASSWORD accordingly
+      CREATE USER PATRONI_REWIND_USERNAME WITH ENCRYPTED PASSWORD 'PATRONI_REWIND_PASSWORD';
+      GRANT EXECUTE ON function pg_catalog.pg_ls_dir(text, boolean, boolean) TO PATRONI_REWIND_USERNAME;
+      GRANT EXECUTE ON function pg_catalog.pg_stat_file(text, boolean) TO PATRONI_REWIND_USERNAME;
+      GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text) TO PATRONI_REWIND_USERNAME;
+      GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, boolean) TO PATRONI_REWIND_USERNAME;
+
+#. Perform the following steps on all Postgres nodes. Perform all steps on one node before proceeding with the next node. Start with the primary node, then proceed with each standby node:
+
+   #. If you are running Postgres through systemd, then disable the Postgres systemd unit. This is performed as Patroni manages starting and stopping the Postgres daemon.
+
+   #. Create a YAML configuration file for Patroni. You can use :ref:`Patroni configuration generation and validation tooling <validate_generate_config>` for that.
+
+      * **Note (specific for the primary node):** If you have replication slots being used for replication between cluster members, then it is recommended that you enable ``use_slots`` and configure the existing replication slots as permanent via the ``slots`` configuration item. Be aware that Patroni automatically creates replication slots for replication between members, and drops replication slots that it does not recognize, when ``use_slots`` is enabled. The idea of using permanent slots here is to allow your existing slots to persist while the migration to Patroni is in progress. See :ref:`YAML Configuration Settings <yaml_configuration>` for details.
+
+   #. Start Patroni using the ``patroni`` systemd service unit. It automatically detects that Postgres is already running and starts monitoring the instance.
+
+#. Hand over Postgres "start up procedure" to Patroni. In order to do that you need to restart the cluster members through :ref:`patronictl restart cluster-name member-name <patronictl_restart_parameters>` command. For minimal downtime you might want to split this step into:
+
+   #. Immediate restart of the standby nodes.
+   #. Scheduled restart of the primary node within a maintenance window.
+
+#. If you configured permanent slots in step ``1.2.``, then you should remove them from ``slots`` configuration through :ref:`patronictl edit-config cluster-name member-name <patronictl_edit_config_parameters>` command once the ``restart_lsn`` of the slots created by Patroni is able to catch up with the ``restart_lsn`` of the original slots for the corresponding members. By removing the slots from ``slots`` configuration you will allow Patroni to drop the original slots from your cluster once they are not needed anymore. You can find below an example query to check the ``restart_lsn`` of a couple slots, so you can compare them:
+
+   .. code-block:: sql
+
+      -- Assume original_slot_for_member_x is the name of the slot in your original
+      -- cluster for replicating changes to member X, and slot_for_member_x is the
+      -- slot created by Patroni for that purpose. You need restart_lsn of
+      -- slot_for_member_x to be >= restart_lsn of original_slot_for_member_x
+      SELECT slot_name,
+             restart_lsn
+      FROM pg_replication_slots
+      WHERE slot_name IN (
+          'original_slot_for_member_x',
+          'slot_for_member_x'
+      )
+
+.. _major_upgrade:
 
 Major Upgrade of PostgreSQL Version
 ===================================
 
 The only possible way to do a major upgrade currently is:
 
-1. Stop Patroni
-2. Upgrade PostgreSQL binaries and perform `pg_upgrade <https://www.postgresql.org/docs/current/pgupgrade.html>`_ on the primary node
-3. Update patroni.yml
-4. Remove the initialize key from DCS or wipe complete cluster state from DCS. The second one could be achieved by running ``patronictl remove <cluster-name>``. It is necessary because pg_upgrade runs initdb which actually creates a new database with a new PostgreSQL system identifier.
-5. If you wiped the cluster state in the previous step, you may wish to copy patroni.dynamic.json from old data dir to the new one.  It will help you to retain some PostgreSQL parameters you had set before.
-6. Start Patroni on the primary node.
-7. Upgrade PostgreSQL binaries, update patroni.yml and wipe the data_dir on standby nodes.
-8. Start Patroni on the standby nodes and wait for the replication to complete.
+#. Stop Patroni
+#. Upgrade PostgreSQL binaries and perform `pg_upgrade <https://www.postgresql.org/docs/current/pgupgrade.html>`_ on the primary node
+#. Update patroni.yml
+#. Remove the initialize key from DCS or wipe complete cluster state from DCS. The second one could be achieved by running :ref:`patronictl remove cluster-name <patronictl_remove_parameters>` . It is necessary because pg_upgrade runs initdb which actually creates a new database with a new PostgreSQL system identifier.
+#. If you wiped the cluster state in the previous step, you may wish to copy patroni.dynamic.json from old data dir to the new one.  It will help you to retain some PostgreSQL parameters you had set before.
+#. Start Patroni on the primary node.
+#. Upgrade PostgreSQL binaries, update patroni.yml and wipe the data_dir on standby nodes.
+#. Start Patroni on the standby nodes and wait for the replication to complete.
 
 Running pg_upgrade on standby nodes is not supported by PostgreSQL. If you know what you are doing, you can try the rsync procedure described in https://www.postgresql.org/docs/current/pgupgrade.html instead of wiping data_dir on standby nodes. The safest way is however to let Patroni replicate the data for you.
 

docs/faq.rst

@@ -0,0 +1,329 @@
+.. _faq:
+
+FAQ
+===
+
+In this section you will find answers for the most frequently asked questions about Patroni.
+Each sub-section attempts to focus on different kinds of questions.
+
+We hope that this helps you to clarify most of your questions.
+If you still have further concerns or find yourself facing an unexpected issue, please refer to :ref:`chatting` and :ref:`reporting_bugs` for instructions on how to get help or report issues.
+
+Comparison with other HA solutions
+----------------------------------
+
+Why does Patroni require a separate cluster of DCS nodes while other solutions like ``repmgr`` do not?
+    There are different ways of implementing HA solutions, each of them with their pros and cons.
+
+    Software like ``repmgr`` performs communication among the nodes to decide when actions should be taken.
+
+    Patroni on the other hand relies on the state stored in the DCS. The DCS acts as a source of truth for Patroni to decide what it should do.
+
+    While having a separate DCS cluster can make you bloat your architecture, this approach also makes it less likely for split-brain scenarios to happen in your Postgres cluster.
+
+What is the difference between Patroni and other HA solutions in regards to Postgres management?
+    Patroni does not just manage the high availability of the Postgres cluster but also manages Postgres itself.
+
+    If Postgres nodes do not exist yet, it takes care of bootstrapping the primary and the standby nodes, and also manages Postgres configuration of the nodes. If the Postgres nodes already exist, Patroni will take over management of the cluster.
+
+    Besides the above, Patroni also has self-healing capabilities. In other words, if a primary node fails, Patroni will not only fail over to a replica, but also attempt to rejoin the former primary as a replica of the new primary. Similarly, if a replica fails, Patroni will attempt to rejoin that replica.
+
+    That is way we call Patroni as a "template for HA solutions". It goes further than just managing physical replication: it manages Postgres as a whole.
+
+DCS
+---
+
+Can I use the same ``etcd`` cluster to store data from two or more Patroni clusters?
+    Yes, you can!
+
+    Information about a Patroni cluster is stored in the DCS under a path prefixed with the ``namespace`` and ``scope`` Patroni settings.
+
+    As long as you do not have conflicting namespace and scope across different Patroni clusters, you should be able to use the same DCS cluster to store information from multiple Patroni clusters.
+
+What occurs if I attempt to use the same combination of ``namespace`` and ``scope`` for different Patroni clusters that point to the same DCS cluster?
+    The second Patroni cluster that attempts to use the same ``namespace`` and ``scope`` will not be able to manage Postgres because it will find information related with that same combination in the DCS, but with an incompatible Postgres system identifier.
+    The mismatch on the system identifier causes Patroni to abort the management of the second cluster, as it assumes that refers to a different cluster and that the user has misconfigured Patroni.
+
+    Make sure to use different ``namespace`` / ``scope`` when dealing with different Patroni clusters that share the same DCS cluster.
+
+What occurs if I lose my DCS cluster?
+    The DCS is used to store basically status and the dynamic configuration of the Patroni cluster.
+
+    They very first consequence is that all the Patroni clusters that rely on that DCS will go to read-only mode -- unless :ref:`dcs_failsafe_mode` is enabled.
+
+What should I do if I lose my DCS cluster?
+    There are three possible outcomes upon losing your DCS cluster:
+
+    1. The DCS cluster is fully recovered: this requires no action from the Patroni side. Once the DCS cluster is recovered, Patroni should be able to recover too;
+    2. The DCS cluster is re-created in place, and the endpoints remain the same. No changes are required on the Patroni side;
+    3. A new DCS cluster is created with different endpoints. You will need to update the DCS endpoints in the Patroni configuration of each Patroni node.
+
+    If you face scenario ``2.`` or ``3.`` Patroni will take care of creating the status information again based on the current status of the cluster, and recreate the dynamic configuration on the DCS based on a backup file named ``patroni.dynamic.json`` which is stored inside the Postgres data directory of each member of the Patroni cluster.
+
+What occurs if I lose majority in my DCS cluster?
+    The DCS will become unresponsive, which will cause Patroni to demote the current read/write Postgres node.
+
+    Remember: Patroni relies on the state of the DCS to take actions on the cluster.
+
+    You can use the :ref:`dcs_failsafe_mode` to alleviate that situation.
+
+patronictl
+----------
+
+Do I need to run :ref:`patronictl` in the Patroni host?
+    No, you do not need to do that.
+
+    Running :ref:`patronictl` in the Patroni host is handy if you have access to the Patroni host because you can use the very same configuration file from the ``patroni`` agent for the :ref:`patronictl` application.
+
+    However, :ref:`patronictl` is basically a client and it can be executed from remote machines. You just need to provide it with enough configuration so it can reach the DCS and the REST API of the Patroni member(s).
+
+Why did the information from one of my Patroni members disappear from the output of :ref:`patronictl_list` command?
+    Information shown by :ref:`patronictl_list` is based on the contents of the DCS.
+
+    If information about a member disappeared from the DCS it is very likely that the Patroni agent on that node is not running anymore, or it is not able to communicate with the DCS.
+
+    As the member is not able to update the information, the information eventually expires from the DCS, and consequently the member is not shown anymore in the output of :ref:`patronictl_list`.
+
+Why is the information about one of my Patroni members not up-to-date in the output of :ref:`patronictl_list` command?
+    Information shown by :ref:`patronictl_list` is based on the contents of the DCS.
+
+    By default, that information is updated by Patroni roughly every ``loop_wait`` seconds.
+    In other words, even if everything is normally functional you may still see a "delay" of up to ``loop_wait`` seconds in the information stored in the DCS.
+
+    Be aware that that is not a rule, though. Some operations performed by Patroni cause it to immediately update the DCS information.
+
+Configuration
+-------------
+
+What is the difference between dynamic configuration and local configuration?
+    Dynamic configuration (or global configuration) is the configuration stored in the DCS, and which is applied to all members of the Patroni cluster.
+    This is primarily where you should store your configuration.
+
+    Settings that are specific to a node, or settings that you would like to overwrite the global configuration with, you should set only on the desired Patroni member as a local configuration.
+    That local configuration can be specified either through the configuration file or through environment variables.
+
+    See more in :ref:`patroni_configuration`.
+
+What are the types of configuration in Patroni, and what is the precedence?
+    The types are:
+
+    * Dynamic configuration: applied to all members;
+    * Local configuration: applied to the local member, overrides dynamic configuration;
+    * Environment configuration: applied to the local member, overrides both dynamic and local configuration.
+
+    **Note:** some Postgres GUCs can only be set globally, i.e., through dynamic configuration. Besides that, there are GUCs which Patroni enforces a hard-coded value.
+
+    See more in :ref:`patroni_configuration`.
+
+Is there any facility to help me create my Patroni configuration file?
+    Yes, there is.
+
+    You can use ``patroni --generate-sample-config`` or ``patroni --generate-config`` commands to generate a sample Patroni configuration or a Patroni configuration based on an existing Postgres instance, respectively.
+
+    Please refer to :ref:`generate_sample_config` and :ref:`generate_config` for more details.
+
+I changed my parameters under ``bootstrap.dcs`` configuration but Patroni is not applying the changes to the cluster members. What is wrong?
+    The values configured under ``bootstrap.dcs`` are only used when bootstrapping a fresh cluster. Those values will be written to the DCS during the bootstrap.
+
+    After the bootstrap phase finishes, you will only be able to change the dynamic configuration through the DCS.
+
+    Refer to the next question for more details.
+
+How can I change my dynamic configuration?
+    You need to change the configuration in the DCS. That is accomplished either through:
+
+    * :ref:`patronictl_edit_config`; or
+    * A ``PATCH`` request to :ref:`config_endpoint`.
+
+How can I change my local configuration?
+    You need to change the configuration file of the corresponding Patroni member and signal the Patroni agent with ``SIHGUP``. You can do that using either of these approaches:
+
+    * Send a ``POST`` request to the REST API :ref:`reload_endpoint`; or
+    * Run :ref:`patronictl_reload`; or
+    * Locally signal the Patroni process with ``SIGHUP``:
+
+        * If you started Patroni through systemd, you can use the command ``systemctl reload PATRONI_UNIT.service``, ``PATRONI_UNIT`` being the name of the Patroni service; or
+        * If you started Patroni through other means, you will need to identify the ``patroni`` process and run ``kill -s HUP PID``, ``PID`` being the process ID of the ``patroni`` process.
+
+    **Note:** there are cases where a reload through the :ref:`patronictl_reload` may not work:
+
+    * Expired REST API certificates: you can mitigate that by using the ``-k`` option of the :ref:`patronictl`;
+    * Wrong credentials: for example when changing ``restapi`` or ``ctl`` credentials in the configuration file, and using that same configuration file for Patroni and :ref:`patronictl`.
+
+How can I change my environment configuration?
+    The environment configuration is only read by Patroni during startup.
+
+    With that in mind, if you change the environment configuration you will need to restart the corresponding Patroni agent.
+
+    Take care to not cause a failover in the cluster! You might be interested in checking :ref:`patronictl_pause`.
+
+What occurs if I change a Postgres GUC that requires a reload?
+    When you change the dynamic or the local configuration as explained in the previous questions, Patroni will take care of reloading the Postgres configuration for you.
+
+What occurs if I change a Postgres GUC that requires a restart?
+    Patroni will mark the affected members with a flag of ``pending restart``.
+
+    It is up to you to determine when and how to restart the members. That can be accomplished either through:
+
+    * :ref:`patronictl_restart`; or
+    * A ``POST`` request to :ref:`restart_endpoint`.
+
+    **Note:** some Postgres GUCs require a special management in terms of the order for restarting the Postgres nodes. Refer to :ref:`shared_memory_gucs` for more details.
+
+What is the difference between ``etcd`` and ``etcd3`` in Patroni configuration?
+    ``etcd`` uses the API version 2 of ``etcd``, while ``etcd3`` uses the API version 3 of ``etcd``.
+
+    Be aware that information stored by the API version 2 is not manageable by API version 3 and vice-versa.
+
+    We recommend that you configure ``etcd3`` instead of ``etcd`` because:
+
+    * API version 2 is disabled by default from Etcd v3.4 onward;
+    * API version 2 will be completely removed on Etcd v3.6.
+
+I have ``use_slots`` enabled in my Patroni configuration, but when a cluster member goes offline for some time, the replication slot used by that member is dropped on the upstream node. What can I do to avoid that issue?
+    You can configure a permanent physical replication slot for the members.
+
+    Since Patroni ``3.2.0`` it is now possible to have member slots as permanent slots managed by Patroni.
+
+    Patroni will create the permanent physical slots on all nodes, and make sure to not remove the slots, as well as to advance the slots' LSN on all nodes according to the LSN that has been consumed by the member.
+
+    Later, if you decide to remove the corresponding member, it's **your responsability** to adjust the permanent slots configuration, otherwise Patroni will keep the slots around forever.
+
+    **Note:** on Patroni older than ``3.2.0`` you could still have member slots configured as permanent physical slots, however they would be managed only on the current leader. That is, in case of failover/switchover these slots would be created on the new leader, but that wouldn't guarantee that it had all WAL segments for the absent node.
+
+    **Note:** even with Patroni ``3.2.0`` there might be a small race condition. In the very beginning, when the slot is created on the replica it could be ahead of the same slot on the leader and in case if nobody is consuming the slot there is still a chance that some files could be missing after failover. With that in mind, it is recommended that you configure continuous archiving, which makes it possible to restore required WALs or perform PITR.
+
+What is the difference between ``loop_wait``, ``retry_timeout`` and ``ttl``?
+    Patroni performs what we call a HA cycle from time to time. On each HA cycle it takes care of performing a series of checks on the cluster to determine its healthiness, and depending on the status it may take actions, like failing over to a standby.
+
+    ``loop_wait`` determines for how long, in seconds, Patroni should sleep before performing a new cycle of HA checks.
+
+    ``retry_timeout`` sets the timeout for retry operations on the DCS and on Postgres. For example: if the DCS is unresponsive for more than ``retry_timeout`` seconds, Patroni might demote the primary node as a security action.
+
+    ``ttl`` sets the lease time on the ``leader`` lock in the DCS. If the current leader of the cluster is not able to renew the lease during its HA cycles for longer than ``ttl``, then the lease will expire and that will trigger a ``leader race`` in the cluster.
+
+    **Note:** when modifying these settings, please keep in mind that Patroni enforces the rule and minimal values described in :ref:`dynamic_configuration` section of the docs.
+
+Postgres management
+-------------------
+
+Can I change Postgres GUCs directly in Postgres configuration?
+    You can, but you should avoid that.
+
+    Postgres configuration is managed by Patroni, and attempts to edit the configuration files may end up being frustrated by Patroni as it may eventually overwrite them.
+
+    There are a few options available to overcome the management performed by Patroni:
+
+    * Change Postgres GUCs through ``$PGDATA/postgresql.base.conf``; or
+    * Define a ``postgresql.custom_conf`` which will be used instead of ``postgresql.base.conf`` so you can manage that externally; or
+    * Change GUCs using ``ALTER SYSTEM`` / ``ALTER DATABASE`` / ``ALTER USER``.
+
+    You can find more information about that in the section :ref:`important_configuration_rules`.
+
+    In any case we recommend that you manage all the Postgres configuration through Patroni. That will centralize the management and make it easier to debug Patroni when needed.
+
+Can I restart Postgres nodes directly?
+    No, you should **not** attempt to manage Postgres directly!
+
+    Any attempt of bouncing the Postgres server without Patroni can lead your cluster to face failovers.
+
+    If you need to manage the Postgres server, do that through the ways exposed by Patroni.
+
+Is Patroni able to take over management of an already existing Postgres cluster?
+    Yes, it can!
+
+    Please refer to :ref:`existing_data` for detailed instructions.
+
+How does Patroni manage Postgres?
+    Patroni takes care of bringing Postgres up and down by running the Postgres binaries, like ``pg_ctl`` and ``postgres``.
+
+    With that in mind you **MUST** disable any other sources that could manage the Postgres clusters, like the systemd units, e.g. ``postgresql.service``. Only Patroni should be able to start, stop and promote Postgres instances in the cluster. Not doing so may result in split-brain scenarios. For example: if the node running as a primary failed and the unit ``postgresql.service`` is enabled, it may bring Postgres back up and cause a split-brain.
+
+Concepts and requirements
+-------------------------
+
+Which are the applications that make part of Patroni?
+    Patroni basically ships a couple applications:
+
+    * ``patroni``: This is the Patroni agent, which takes care of managing a Postgres node;
+    * ``patronictl``: This is a command-line utility used to interact with a Patroni cluster (perform switchovers, restarts, changes in the configuration, etc.). Please find more information in :ref:`patronictl`.
+
+What is a ``standby cluster`` in Patroni?
+    It is a cluster that does not have any primary Postgres node running, i.e., there is no read/write member in the cluster.
+
+    These kinds of clusters exist to replicate data from another cluster and are usually useful when you want to replicate data across data centers.
+
+    There will be a leader in the cluster which will be a standby in charge of replicating changes from a remote Postgres node.
+    Then, there will be a set of standbys configured with cascading replication from such leader member.
+
+    **Note:** the standby cluster doesn't know anything about the source cluster which it is replicating from -- it can even use ``restore_command`` instead of WAL streaming, and may use an absolutely independent DCS cluster.
+
+    Refer to :ref:`standby_cluster` for more details.
+
+What is a ``leader`` in Patroni?
+    A ``leader`` in Patroni is like a coordinator of the cluster.
+
+    In a regular Patroni cluster, the ``leader`` will be the read/write node.
+
+    In a standby Patroni cluster, the ``leader`` (AKA ``standby leader``) will be in charge of replicating from a remote Postgres node, and cascading those changes to the other members of the standby cluster.
+
+Does Patroni require a minimum number of Postgres nodes in the cluster?
+    No, you can run Patroni with any number of Postgres nodes.
+
+    Remember: Patroni is decoupled from the DCS.
+
+What does ``pause`` mean in Patroni?
+    Pause is an operation exposed by Patroni so the user can ask Patroni to step back in regards to Postgres management.
+
+    That is mainly useful when you want to perform maintenance on the cluster, and would like to avoid that Patroni takes decisions related with HA, like failing over to a standby when you stop the primary.
+
+    You can find more information about that in :ref:`pause`.
+
+Automatic failover
+------------------
+
+How does the automatic failover mechanism of Patroni work?
+    Patroni automatic failover is based on what we call ``leader race``.
+
+    Patroni stores the cluster's status in the DCS, among them a ``leader`` lock which holds the name of the Patroni member which is the current ``leader`` of the cluster.
+
+    That ``leader`` lock has a time-to-live associated with it. If the leader node fails to update the lease of the ``leader`` lock in time, the key will eventually expire from the DCS.
+
+    When the ``leader`` lock expires, it triggers what Patroni calls a ``leader race``: all nodes start performing checks to determine if they are the best candidates for taking over the ``leader`` role.
+    Some of these checks include calls to the REST API of all other Patroni members.
+
+    All Patroni members that find themselves as the best candidate for taking over the ``leader`` lock will attempt to do so.
+    The first Patroni member that is able to take the ``leader`` lock will promote itself to a read/write node (or ``standby leader``), and the others will be configured to follow it.
+
+Can I temporarily disable automatic failover in the Patroni cluster?
+    Yes, you can!
+
+    You can achieve that by temporarily pausing the cluster.
+    This is typically useful for performing maintenance.
+
+    When you want to resume the automatic failover of the cluster, you just need to unpause it.
+
+    You can find more information about that in :ref:`pause`.
+
+Bootstrapping and standbys creation
+-----------------------------------
+
+How does Patroni create a primary Postgres node? What about a standby Postgres node?
+    By default Patroni will use ``initdb`` to bootstrap a fresh cluster, and ``pg_basebackup`` to create standby nodes from a copy of the ``leader`` member.
+
+    You can customize that behavior by writing your custom bootstrap methods, and your custom replica creation methods.
+
+    Custom methods are usually useful when you want to restore backups created by backup tools like pgBackRest or Barman, for example.
+
+    For detailed information please refer to :ref:`custom_bootstrap` and :ref:`custom_replica_creation`.
+
+Monitoring
+----------
+
+How can I monitor my Patroni cluster?
+    Patroni exposes a couple handy endpoints in its :ref:`rest_api`:
+
+    * ``/metrics``: exposes monitoring metrics in a format that can be consumed by Prometheus;
+    * ``/patroni``: exposes the status of the cluster in a JSON format. The information shown here is very similar to what is shown by the ``/metrics`` endpoint.
+
+    You can use those endpoints to implement monitoring checks.

docs/ha_multi_dc.rst

@@ -0,0 +1,54 @@
+.. _ha_multi_dc:
+
+===================
+HA multi datacenter
+===================
+
+The high availability of a PostgreSQL cluster deployed in multiple data centers is based on replication, which can be synchronous or asynchronous (`replication_modes <replication_modes.rst>`_).
+
+In both cases, it is important to be clear about the following concepts:
+
+- Postgres can run as primary or standby leader only when it owns the leading key and can update the leading key.
+- You should run the odd number of etcd, ZooKeeper or Consul nodes: 3 or 5!
+
+Synchronous Replication
+-----------------------
+
+To have a multi DC cluster that can automatically tolerate a zone drop, a minimum of 3 is required.
+
+The architecture diagram would be the following:
+
+.. image:: _static/multi-dc-synchronous-replication.png
+
+We must deploy a cluster of etcd, ZooKeeper or Consul through the different DC, with a minimum of 3 nodes, one in each zone.
+
+Regarding postgres, we must deploy at least 2 nodes, in different DC. Then you have to set ``synchronous_mode: true`` in the global :ref:`dynamic configuration <dynamic_configuration>`.
+
+This enables sync replication and the primary node will choose one of the nodes as synchronous.
+
+Asynchronous Replication
+------------------------
+
+With only two data centers it would be better to have two independent etcd clusters and run Patroni :ref:`standby cluster <standby_cluster>` in the second data center. If the first site is down, you can MANUALLY promote the ``standby_cluster``.
+
+The architecture diagram would be the following:
+
+.. image:: _static/multi-dc-asynchronous-replication.png
+
+Automatic promotion is not possible, because DC2 will never able to figure out the state of DC1.
+
+You should not use ``pg_ctl promote`` in this scenario, you need "manually promote" the healthy cluster by removing ``standby_cluster`` section from the :ref:`dynamic configuration <dynamic_configuration>`.
+
+.. warning::
+    If the source cluster is still up and running and you promote the standby cluster you create a split-brain.
+
+In case you want to return to the "initial" state, there are only two ways of resolving it:
+
+- Add the standby_cluster section back and it will trigger pg_rewind, but there are chances that pg_rewind will fail.
+- Rebuild the standby cluster from scratch.
+
+Before promoting standby cluster one have to manually ensure that the source cluster is down (STONITH). When DC1 recovers, the cluster has to be converted to a standby cluster.
+
+Before doing that you may manually examine the database and extract all changes that happened between the time when network between DC1 and DC2 has stopped working and the time when you manually stopped the cluster in DC1.
+
+Once extracted, you may also manually apply these changes to the cluster in DC2.

docs/index.rst

@@ -6,11 +6,13 @@
 Introduction
 ============
 
-Patroni is a template for you to create your own customized, high-availability solution using Python and - for maximum accessibility - a distributed configuration store like `ZooKeeper <https://zookeeper.apache.org/>`__, `etcd <https://github.com/coreos/etcd>`__, `Consul <https://github.com/hashicorp/consul>`__ or `Kubernetes <https://kubernetes.io>`__. Database engineers, DBAs, DevOps engineers, and SREs who are looking to quickly deploy HA PostgreSQL in the datacenter-or anywhere else-will hopefully find it useful.
+Patroni is a template for high availability (HA) PostgreSQL solutions using Python. For maximum accessibility, Patroni supports a variety of distributed configuration stores like `ZooKeeper <https://zookeeper.apache.org/>`__, `etcd <https://github.com/coreos/etcd>`__, `Consul <https://github.com/hashicorp/consul>`__ or `Kubernetes <https://kubernetes.io>`__. Database engineers, DBAs, DevOps engineers, and SREs who are looking to quickly deploy HA PostgreSQL in datacenters — or anywhere else — will hopefully find it useful.
 
 We call Patroni a "template" because it is far from being a one-size-fits-all or plug-and-play replication system. It will have its own caveats. Use wisely. There are many ways to run high availability with PostgreSQL; for a list, see the `PostgreSQL Documentation <https://wiki.postgresql.org/wiki/Replication,_Clustering,_and_Connection_Pooling>`__.
 
-Currently supported PostgreSQL versions: 9.3 to 15.
+Currently supported PostgreSQL versions: 9.3 to 16.
+
+**Note to Citus users**: Starting from 3.0 Patroni nicely integrates with the `Citus <https://github.com/citusdata/citus>`__ database extension to Postgres. Please check the :ref:`Citus support page <citus>` in the Patroni documentation for more info about how to use Patroni high availability together with a Citus distributed cluster.
 
 **Note to Kubernetes users**: Patroni can run natively on top of Kubernetes. Take a look at the :ref:`Kubernetes <kubernetes>` chapter of the Patroni documentation.
 
@@ -20,23 +22,34 @@ Currently supported PostgreSQL versions: 9.3 to 15.
    :caption: Contents:
 
    README
-   dynamic_configuration
+   installation
+   patroni_configuration
    rest_api
-   existing_data
-   ENVIRONMENT
-   SETTINGS
-   security
+   patronictl
    replica_bootstrap
    replication_modes
-   pause
-   kubernetes
    watchdog
+   pause
+   dcs_failsafe_mode
+   kubernetes
+   citus
+   existing_data
+   security
+   ha_multi_dc
+   faq
    releases
    CONTRIBUTING
 
 Indices and tables
 ==================
 
-* :ref:`genindex`
-* :ref:`modindex`
-* :ref:`search`
+.. ifconfig:: builder == 'html'
+
+  * :ref:`genindex`
+  * :ref:`modindex`
+  * :ref:`search`
+
+.. ifconfig:: builder != 'html'
+
+  * :ref:`genindex`
+  * :ref:`search`

docs/installation.rst

@@ -0,0 +1,198 @@
+.. _installation:
+
+Installation
+============
+
+Pre-requirements for Mac OS
+---------------------------
+
+To install requirements on a Mac, run the following:
+
+.. code-block:: shell
+
+    brew install postgresql etcd haproxy libyaml python
+
+.. _psycopg2_install_options:
+
+Psycopg
+-------
+
+Starting from `psycopg2-2.8`_ the binary version of psycopg2 will no longer be installed by default. Installing it from
+the source code requires C compiler and postgres+python dev packages. Since in the python world it is not possible to
+specify dependency as ``psycopg2 OR psycopg2-binary`` you will have to decide how to install it.
+
+There are a few options available:
+
+1. Use the package manager from your distro
+
+.. code-block:: shell
+
+    sudo apt-get install python3-psycopg2  # install psycopg2 module on Debian/Ubuntu
+    sudo yum install python3-psycopg2      # install psycopg2 on RedHat/Fedora/CentOS
+
+2. Specify one of `psycopg`, `psycopg2`, or `psycopg2-binary` in the :ref:`list of dependencies <extras>` when installing Patroni with pip.
+
+
+.. _extras:
+
+General installation for pip
+----------------------------
+
+Patroni can be installed with pip:
+
+.. code-block:: shell
+
+    pip install patroni[dependencies]
+
+where ``dependencies`` can be either empty, or consist of one or more of the following:
+
+etcd or etcd3
+    `python-etcd` module in order to use Etcd as Distributed Configuration Store (DCS)
+consul
+    `python-consul` module in order to use Consul as DCS
+zookeeper
+    `kazoo` module in order to use Zookeeper as DCS
+exhibitor
+    `kazoo` module in order to use Exhibitor as DCS (same dependencies as for Zookeeper)
+kubernetes
+    `kubernetes` module in order to use Kubernetes as DCS in Patroni
+raft
+    `pysyncobj` module in order to use python Raft implementation as DCS
+aws
+    `boto3` in order to use AWS callbacks
+jsonlogger
+    `python-json-logger` module in order to enable :ref:`logging <log_settings>` in json format
+all
+    all of the above (except psycopg family)
+psycopg
+    `psycopg[binary]>=3.0.0` module
+psycopg2
+    `psycopg2>=2.5.4` module
+psycopg2-binary
+    `psycopg2-binary` module
+
+For example, the command in order to install Patroni together with psycopg3, dependencies for Etcd as a DCS, and AWS callbacks is:
+
+.. code-block:: shell
+
+    pip install patroni[psycopg3,etcd3,aws]
+
+Note that external tools to call in the replica creation or custom bootstrap scripts (i.e. WAL-E) should be installed
+independently of Patroni.
+
+.. _package_installation:
+
+Package installation on Linux
+-----------------------------
+
+Patroni packages may be available for your operating system, produced by the Postgres community for:
+
+* RHEL, RockyLinux, AlmaLinux;
+* Debian and Ubuntu;
+* SUSE Enterprise Linux.
+
+You can also find packages for direct dependencies of Patroni, like python modules that might not be available in
+the official operating system repositories.
+
+For more information see the `PGDG repository`_ documentation.
+
+If you are on a RedHat Enterprise Linux derivative operating system you may also require packages from EPEL, see
+`EPEL repository`_ documentation.
+
+Once you have installed the PGDG repository for your OS you can install patroni.
+
+.. note::
+
+    Patroni packages are not maintained by the Patroni developers, but rather by the Postgres community. If you
+    require support please first try connecting on `Postgres slack`_.
+
+Installing on Debian derivatives
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+With PGDG repo installed, see :ref:`above <package_installation>`, install Patroni via apt run:
+
+.. code-block:: shell
+
+    apt-get install patroni
+
+Installing on RedHat derivatives
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+With PGDG repo installed, see :ref:`above <package_installation>`, install patroni with an etcd DCS via dnf on RHEL 9
+(and derivatives) run:
+
+.. code-block:: shell
+
+    dnf install patroni patroni-etcd
+
+You can install etcd from PGDG if your RedHat derivative distribution does not provide packages. On the nodes that will
+host the DCS run:
+
+.. code-block:: shell
+
+    dnf install 'dnf-command(config-manager)'
+    dnf config-manager --enable pgdg-rhel9-extras
+    dnf install etcd
+
+You can replace the version of RHEL with `8` in the repo to make `pgdg-rhel8-extras` if needed. The repo name is still
+`pgdg-rhelN-extras` on RockyLinux, AlmaLinux, Oracle Linux, etc...
+
+Installing on SUSE Enterprise Linux
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You might need to enable the SUSE PackageHub repositories for some dependencies. see `SUSE PackageHub`_ documentation.
+
+For SLES 15 with PGDG repo installed, see :ref:`above <package_installation>`, you can install patroni using:
+
+.. code-block:: shell
+
+    zypper install patroni patroni-etcd
+
+With the SUSE PackageHub repo enabled you can also install etcd:
+
+.. code-block:: shell
+
+    SUSEConnect -p PackageHub/15.5/x86_64
+    zypper install etcd
+
+Upgrading
+---------
+
+Upgrading patroni is a very simple process, just update the software installation and restart the Patroni daemon on
+each node in the cluster.
+
+However, restarting the Patroni daemon will result in a Postgres database restart. In some situations this may cause
+a failover of the primary node in your cluster, therefore it is recommended to put the cluster into maintenance mode
+until the Patroni daemon restart has been completed.
+
+To put the cluster in maintenance mode, run the following command on one of the patroni nodes:
+
+.. code-block:: shell
+
+    patronictl pause --wait
+
+Then on each node in the cluster, perform the package upgrade required for your OS:
+
+.. code-block:: shell
+
+    apt-get update && apt-get install patroni patroni-etcd
+
+Restart the patroni daemon process on each node:
+
+.. code-block:: shell
+
+    systemctl restart patroni
+
+Then finally resume monitoring of Postgres with patroni to take it out of maintenance mode:
+
+.. code-block:: shell
+
+    patronictl resume --wait
+
+The cluster will now be full operational with the new version of Patroni.
+
+.. _psycopg2-2.8: http://initd.org/psycopg/articles/2019/04/04/psycopg-28-released/
+.. _PGDG repository: https://www.postgresql.org/download/linux/
+.. _EPEL repository: https://docs.fedoraproject.org/en-US/epel/
+.. _SUSE PackageHub: https://packagehub.suse.com/how-to-use/
+.. _Postgres slack: http://pgtreats.info/slack-invite

docs/kubernetes.rst

@@ -23,10 +23,7 @@ Use ConfigMaps
 In this mode, Patroni will create ConfigMaps instead of Endpoints and store keys inside meta-data of those ConfigMaps.
 Changing the leader takes at least two updates, one to the leader ConfigMap and another to the respective Endpoint.
 
-There are two ways to direct the traffic to the Postgres leader:
-
-- use the `callback script <https://github.com/zalando/patroni/blob/master/kubernetes/callback.py>`_ provided by Patroni
-- configure the Kubernetes Postgres service to use the label selector with the `role_label` (configured in patroni configuration).
+To direct the traffic to the Postgres leader you need to configure the Kubernetes Postgres service to use the label selector with the `role_label` (configured in patroni configuration).
 
 Note that in some cases, for instance, when running on OpenShift, there is no alternative to using ConfigMaps.
 
@@ -35,11 +32,63 @@ Configuration
 
 Patroni Kubernetes :ref:`settings <kubernetes_settings>` and :ref:`environment variables <kubernetes_environment>` are described in the general chapters of the documentation.
 
+.. _kubernetes_role_values:
+
+Customize role label
+^^^^^^^^^^^^^^^^^^^^
+
+By default, Patroni will set corresponding labels on the pod it runs in based on node's role, such as ``role=master``.
+The key and value of label can be customized by `kubernetes.role_label`, `kubernetes.leader_label_value`, `kubernetes.follower_label_value` and `kubernetes.standby_leader_label_value`.
+
+Note that if you migrate from default role labels to custom ones, you can reduce downtime by following migration steps:
+
+1. Add a temporary label using original role value for the pod with `kubernetes.tmp_role_label` (like ``tmp_role``). Once pods are restarted they will get following labels set by Patroni:
+
+  .. code:: YAML
+
+    labels:
+      cluster-name: foo
+      role: master
+      tmp_role: master
+
+2. After all pods have been updated, modify the service selector to select the temporary label.
+
+  .. code:: YAML
+
+    selector:
+      cluster-name: foo
+      tmp_role: master
+
+3. Add your custom role label (e.g., set `kubernetes.leader_label_value=primary`). Once pods are restarted they will get following new labels set by Patroni:
+
+  .. code:: YAML
+
+    labels:
+      cluster-name: foo
+      role: primary
+      tmp_role: master
+
+4. After all pods have been updated again, modify the service selector to use new role value.
+
+  .. code:: YAML
+
+    selector:
+      cluster-name: foo
+      role: primary
+
+5. Finally, remove the temporary label from your configuration and update all pods.
+
+  .. code:: YAML
+
+    labels:
+      cluster-name: foo
+      role: primary
+
 Examples
 --------
 
 - The `kubernetes <https://github.com/zalando/patroni/tree/master/kubernetes>`__ folder of the Patroni repository contains
-  examples of the Docker image, the Kubernetes manifest and the callback script in order to test Patroni Kubernetes setup.
+  examples of the Docker image, and the Kubernetes manifest to test Patroni Kubernetes setup.
   Note that in the current state it will not be able to use PersistentVolumes because of permission issues.
 
 - You can find the full-featured Docker image that can use Persistent Volumes in the

docs/patroni_configuration.rst

@@ -0,0 +1,253 @@
+.. _patroni_configuration:
+
+Patroni configuration
+=====================
+
+.. toctree::
+   :hidden:
+
+   dynamic_configuration
+   yaml_configuration
+   ENVIRONMENT
+
+
+There are 3 types of Patroni configuration:
+
+- Global :ref:`dynamic configuration <dynamic_configuration>`.
+	These options are stored in the DCS (Distributed Configuration Store) and applied on all cluster nodes.
+	Dynamic configuration can be set at any time using :ref:`patronictl_edit_config` tool or Patroni :ref:`REST API <rest_api>`.
+	If the options changed are not part of the startup configuration, they are applied asynchronously (upon the next wake up cycle)
+	to every node, which gets subsequently reloaded.
+	If the node requires a restart to apply the configuration (for `PostgreSQL parameters <https://www.postgresql.org/docs/current/view-pg-settings.html>`__ with context postmaster, if their values
+	have changed), a special flag ``pending_restart`` indicating this is set in the members.data JSON.
+	Additionally, the node status indicates this by showing ``"restart_pending": true``.
+
+- Local :ref:`configuration file <yaml_configuration>` (patroni.yml).
+	These options are defined in the configuration file and take precedence over dynamic configuration.
+	``patroni.yml`` can be changed and reloaded at runtime (without restart of Patroni) by sending SIGHUP to the Patroni process, performing ``POST /reload`` REST-API request or executing :ref:`patronictl_reload`. Local configuration can be either a single YAML file or a directory. When it is a directory, all YAML files in that directory are loaded one by one in sorted order. In case a key is defined in multiple files, the occurrence in the last file takes precedence.
+
+- :ref:`Environment configuration <environment>`.
+	It is possible to set/override some of the "Local" configuration parameters with environment variables.
+	Environment configuration is very useful when you are running in a dynamic environment and you don't know some of the parameters in advance (for example it's not possible to know your external IP address when you are running inside ``docker``).
+
+.. _important_configuration_rules:
+
+Important rules
+---------------
+
+PostgreSQL parameters controlled by Patroni
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Some of the PostgreSQL parameters **must hold the same values on the primary and the replicas**. For those, **values set either in the local patroni configuration files or via the environment variables take no effect**. To alter or set their values one must change the shared configuration in the DCS. Below is the actual list of such parameters together with the default values:
+
+- **max_connections**: 100
+- **max_locks_per_transaction**: 64
+- **max_worker_processes**: 8
+- **max_prepared_transactions**: 0
+- **wal_level**: hot_standby
+- **track_commit_timestamp**: off
+
+For the parameters below, PostgreSQL does not require equal values among the primary and all the replicas. However, considering the possibility of a replica to become the primary at any time, it doesn't really make sense to set them differently; therefore, **Patroni restricts setting their values to the** :ref:`dynamic configuration <dynamic_configuration>`.
+
+- **max_wal_senders**: 5
+- **max_replication_slots**: 5
+- **wal_keep_segments**: 8
+- **wal_keep_size**: 128MB
+
+These parameters are validated to ensure they are sane, or meet a minimum value.
+
+There are some other Postgres parameters controlled by Patroni:
+
+- **listen_addresses** - is set either from ``postgresql.listen`` or from ``PATRONI_POSTGRESQL_LISTEN`` environment variable
+- **port** - is set either from ``postgresql.listen`` or from ``PATRONI_POSTGRESQL_LISTEN`` environment variable
+- **cluster_name** - is set either from ``scope`` or from ``PATRONI_SCOPE`` environment variable
+- **hot_standby: on**
+- **wal_log_hints: on** - for Postgres 9.4 and newer.
+
+To be on the safe side parameters from the above lists are not written into ``postgresql.conf``, but passed as a list of arguments to the ``pg_ctl start`` which gives them the highest precedence, even above `ALTER SYSTEM <https://www.postgresql.org/docs/current/static/sql-altersystem.html>`__
+
+There also are some parameters like **postgresql.listen**, **postgresql.data_dir** that **can be set only locally**, i.e. in the Patroni :ref:`config file <yaml_configuration>` or via :ref:`configuration <environment>` variable. In most cases the local configuration will override the dynamic configuration.
+
+
+When applying the local or dynamic configuration options, the following actions are taken:
+
+- The node first checks if there is a `postgresql.base.conf` file or if the ``custom_conf`` parameter is set.
+- If the ``custom_conf`` parameter is set, the file it specifies is used as the base configuration, ignoring `postgresql.base.conf` and `postgresql.conf`.
+- If the ``custom_conf`` parameter is not set and `postgresql.base.conf` exists, it contains the renamed "original" configuration and is used as the base configuration.
+- If there is no ``custom_conf`` nor `postgresql.base.conf`, the original `postgresql.conf` is renamed to `postgresql.base.conf` and used as the base configuration.
+- The dynamic options (with the exceptions above) are dumped into the `postgresql.conf` and an include is set in
+  `postgresql.conf` to the base configuration (either `postgresql.base.conf` or the file at ``custom_conf``).
+  Therefore, we would be able to apply new options without re-reading the configuration file to check if the include is present or not.
+- Some parameters that are essential for Patroni to manage the cluster are overridden using the command line.
+- If an option that requires restart is changed (we should look at the context in pg_settings and at the actual
+  values of those options), a pending_restart flag is set on that node. This flag is reset on any restart.
+
+The parameters would be applied in the following order (run-time are given the highest priority):
+
+1. load parameters from file `postgresql.base.conf` (or from a ``custom_conf`` file, if set)
+2. load parameters from file `postgresql.conf`
+3. load parameters from file `postgresql.auto.conf`
+4. run-time parameter using `-o --name=value`
+
+This allows configuration for all the nodes (2), configuration for a specific node using ``ALTER SYSTEM`` (3) and ensures that parameters essential to the running of Patroni are enforced (4), as well as leaves room for configuration tools that manage `postgresql.conf` directly without involving Patroni (1).
+
+.. _shared_memory_gucs:
+
+PostgreSQL parameters that touch shared memory
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+PostgreSQL has some parameters that determine the size of the shared memory used by them:
+
+- **max_connections**
+- **max_prepared_transactions**
+- **max_locks_per_transaction**
+- **max_wal_senders**
+- **max_worker_processes**
+
+Changing these parameters require a PostgreSQL restart to take effect, and their shared memory structures cannot be smaller on the standby nodes than on the primary node.
+
+As explained before, Patroni restrict changing their values through :ref:`dynamic configuration <dynamic_configuration>`, which usually consists of:
+
+1. Applying changes through :ref:`patronictl_edit_config` (or via REST API ``/config`` endpoint)
+2. Restarting nodes through :ref:`patronictl_restart` (or via REST API ``/restart`` endpoint)
+
+**Note:** please keep in mind that you should perform a restart of the PostgreSQL nodes through :ref:`patronictl_restart` command, or via REST API ``/restart`` endpoint. An attempt to restart PostgreSQL by restarting the Patroni daemon, e.g. by executing ``systemctl restart patroni``, can cause a failover to occur in the cluster, if you are restarting the primary node.
+
+However, as those settings manage shared memory, some extra care should be taken when restarting the nodes:
+
+* If you want to **increase** the value of any of those settings:
+
+   1. Restart all standbys first
+   2. Restart the primary after that
+
+* If you want to **decrease** the value of any of those settings:
+
+   1. Restart the primary first
+   2. Restart all standbys after that
+
+**Note:** if you attempt to restart all nodes in one go after **decreasing** the value of any of those settings, Patroni will ignore the change and restart the standby with the original setting value, thus requiring that you restart the standbys again later. Patroni does that to prevent the standby to enter in an infinite crash loop, because PostgreSQL quits with a `FATAL` message if you attempt to set any of those parameters to a value lower than what is visible in ``pg_controldata`` on the Standby node. In other words, we can only decrease the setting on the standby once its ``pg_controldata`` is up-to-date with the primary in regards to these changes on the primary.
+
+More information about that can be found at `PostgreSQL Administrator's Overview <https://www.postgresql.org/docs/current/hot-standby.html#HOT-STANDBY-ADMIN>`__.
+
+Patroni configuration parameters
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Also the following Patroni configuration options **can be changed only dynamically**:
+
+- **ttl**: 30
+- **loop_wait**: 10
+- **retry_timeouts**: 10
+- **maximum_lag_on_failover**: 1048576
+- **max_timelines_history**: 0
+- **check_timeline**: false
+- **postgresql.use_slots**: true
+
+Upon changing these options, Patroni will read the relevant section of the configuration stored in DCS and change its run-time values.
+
+Patroni nodes are dumping the state of the DCS options to disk upon for every change of the configuration into the file ``patroni.dynamic.json`` located in the Postgres data directory. Only the leader is allowed to restore these options from the on-disk dump if these are completely absent from the DCS or if they are invalid.
+
+
+.. _validate_generate_config:
+
+Configuration generation and validation
+---------------------------------------
+
+Patroni provides command-line interfaces for a Patroni :ref:`local configuration <yaml_configuration>` generation and validation. Using the ``patroni`` executable you can:
+
+- Create a sample local Patroni configuration;
+- Create a Patroni configuration file for the locally running PostgreSQL instance (e.g. as a preparation step for the :ref:`Patroni integration <existing_data>`);
+- Validate a given Patroni configuration file.
+
+.. _generate_sample_config:
+
+Sample Patroni configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code:: text
+
+   patroni --generate-sample-config [configfile]
+
+Description
+"""""""""""
+
+Generate a sample Patroni configuration file in ``yaml`` format.
+Parameter values are defined using the :ref:`Environment configuration <environment>`, otherwise, if not set, the defaults used in Patroni or the ``#FIXME`` string for the values that should be later defined by the user.
+
+Some default values are defined based on the local setup:
+
+   -  **postgresql.listen**: the IP address returned by ``gethostname`` call for the current machine's hostname and the standard ``5432`` port.
+   -  **postgresql.connect_address**: the IP address returned by ``gethostname`` call for the current machine's hostname and the standard ``5432`` port.
+   -  **postgresql.authentication.rewind**: is only defined if the PostgreSQL version can be defined from the binary and the version is 11 or later.
+   -  **restapi.listen**: IP address returned by ``gethostname`` call for the current machine's hostname and the standard ``8008`` port.
+   -  **restapi.connect_address**: IP address returned by ``gethostname`` call for the current machine's hostname and the standard ``8008`` port.
+
+Parameters
+""""""""""
+
+``configfile`` - full path to the configuration file used to store the result. If not provided, the result is sent to ``stdout``.
+
+.. _generate_config:
+
+Patroni configuration for a running instance
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code:: text
+
+   patroni --generate-config [--dsn DSN] [configfile]
+
+Description
+"""""""""""
+
+Generate a Patroni configuration in ``yaml`` format for the locally running PostgreSQL instance. 
+Either the provided DSN (takes precedence) or PostgreSQL `environment variables <https://www.postgresql.org/docs/current/libpq-envars.html>`__ will be used for the PostgreSQL connection. If the password is not provided, it should be entered via prompt.
+
+All the non-internal GUCs defined in the source Postgres instance, independently if they were set through a configuration file, through the postmaster command-line, or through environment variables, will be used as the source for the following Patroni configuration parameters:
+
+   -  **scope**: ``cluster_name`` GUC value;
+   -  **postgresql.listen**: ``listen_addresses`` and ``port`` GUC values;
+   -  **postgresql.datadir**: ``data_directory`` GUC value;
+   -  **postgresql.parameters**: ``archive_command``, ``restore_command``, ``archive_cleanup_command``, ``recovery_end_command``, ``ssl_passphrase_command``, ``hba_file``, ``ident_file``, ``config_file`` GUC values;
+   -  **bootstrap.dcs**: all other gathered PostgreSQL GUCs.
+
+If ``scope``, ``postgresql.listen`` or ``postgresql.datadir`` is not set from the Postgres GUCs, the respective :ref:`Environment configuration <environment>` value is used.
+
+Other rules applied for the values definition:
+
+   -  **name**: ``PATRONI_NAME`` environment variable value if set, otherwise the current machine's hostname.
+   -  **postgresql.bin_dir**: path to the Postgres binaries gathered from the running instance.
+   -  **postgresql.connect_address**: the IP address returned by ``gethostname`` call for the current machine's hostname and the port used for the instance connection or the ``port`` GUC value.
+   -  **postgresql.authentication.superuser**: the configuration used for the instance connection;
+   -  **postgresql.pg_hba**: the lines gathered from the source instance's ``hba_file``.
+   -  **postgresql.pg_ident**: the lines gathered from the source instance's ``ident_file``.
+   -  **restapi.listen**: IP address returned by ``gethostname`` call for the current machine's hostname and the standard ``8008`` port.
+   -  **restapi.connect_address**: IP address returned by ``gethostname`` call for the current machine's hostname and the standard ``8008`` port.
+
+Other parameters defined using :ref:`Environment configuration <environment>` are also included into the configuration.
+
+Parameters
+""""""""""
+
+``configfile``
+    Full path to the configuration file used to store the result. If not provided, result is sent to ``stdout``.
+
+``dsn``
+    Optional DSN string for the local PostgreSQL instance to get GUC values from.
+
+
+Validate Patroni configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code:: text
+
+   patroni --validate-config [configfile]
+
+Description
+"""""""""""
+
+Validate the given Patroni configuration and print the information about the failed checks.
+
+Parameters
+""""""""""
+
+``configfile``
+    Full path to the configuration file to check. If not given or file does not exist, will try to read from the ``PATRONI_CONFIG_VARIABLE`` environment variable or, if not set, from the :ref:`Patroni environment variables <environment>`.

docs/pause.rst

@@ -19,7 +19,7 @@ When Patroni runs in a paused mode, it does not change the state of PostgreSQL,
 
 - For the Postgres primary with the leader lock Patroni updates the lock. If the node with the leader lock stops being the primary (i.e. is demoted manually), Patroni will release the lock instead of promoting the node back.
 
-- Manual unscheduled restart, reinitialize and manual failover are allowed. Manual failover is only allowed if the node to failover to is specified. In the paused mode, manual failover does not require a running primary node.
+- Manual unscheduled restart, manual unscheduled failover/switchover and reinitialize are allowed. No scheduled action is allowed. Manual switchover is only allowed if the node to switch over to is specified.
 
 - If 'parallel' primaries are detected by Patroni, it emits a warning, but does not demote the primary without the leader lock.
 
@@ -32,6 +32,6 @@ When Patroni runs in a paused mode, it does not change the state of PostgreSQL,
 User guide
 ----------
 
-``patronictl`` supports ``pause`` and ``resume`` commands.
+``patronictl`` supports :ref:`pause <patronictl_pause>` and :ref:`resume <patronictl_resume>` commands.
 
 One can also issue a ``PATCH`` request to the ``{namespace}/{cluster}/config`` key with ``{"pause": true/false/null}``

docs/replica_bootstrap.rst

@@ -43,19 +43,50 @@ in the configuration files, Patroni supplies two cluster-specific ones:
 
 Passing these two additional flags can be disabled by setting a special ``no_params`` parameter to ``True``.
 
-If the bootstrap script returns 0, Patroni tries to configure and start the PostgreSQL instance produced by it. If any
+If the bootstrap script returns ``0``, Patroni tries to configure and start the PostgreSQL instance produced by it. If any
 of the intermediate steps fail, or the script returns a non-zero value, Patroni assumes that the bootstrap has failed,
 cleans up after itself and releases the initialize lock to give another node the opportunity to bootstrap.
 
 If a ``recovery_conf`` block is defined in the same section as the custom bootstrap method, Patroni will generate a
-``recovery.conf`` before starting the newly bootstrapped instance. Typically, such recovery.conf should contain at least
-one of the ``recovery_target_*`` parameters, together with the ``recovery_target_timeline`` set to ``promote``.
+``recovery.conf`` before starting the newly bootstrapped instance (or set the recovery settings on Postgres configuration if
+running PostgreSQL >= 12).
+Typically, such recovery configuration should contain at least one of the ``recovery_target_*`` parameters, together with the ``recovery_target_timeline`` set to ``promote``.
 
-If ``keep_existing_recovery_conf`` is defined and set to ``True``, Patroni will not remove the existing ``recovery.conf`` file if it exists.
-This is useful when bootstrapping from a backup with tools like pgBackRest that generate the appropriate ``recovery.conf`` for you.
+If ``keep_existing_recovery_conf`` is defined and set to ``True``, Patroni will not remove the existing ``recovery.conf`` file if it exists (PostgreSQL <= 11).
+Similarly, in that case Patroni will not remove the existing ``recovery.signal`` or ``standby.signal`` if either exists, nor will it override the configured recovery settings (PostgreSQL >= 12).
+This is useful when bootstrapping from a backup with tools like pgBackRest that generate the appropriate recovery configuration for you.
+
+Besides that, any additional key/value pairs informed in the custom bootstrap method configuration will be passed as arguments to ``command`` in the format ``--name=value``. For example:
+
+.. code:: YAML
+
+    bootstrap:
+        method: <custom_bootstrap_method_name>
+        <custom_bootstrap_method_name>:
+            command: <path_to_custom_bootstrap_script>
+            arg1: value1
+            arg2: value2
+
+Makes the configured ``command`` to be called additionally with ``--arg1=value1 --arg2=value2`` command-line arguments.
 
  .. note:: Bootstrap methods are neither chained, nor fallen-back to the default one in case the primary one fails
 
+As an example, you are able to bootstrap a fresh Patroni cluster from a Barman backup with a configuration like this:
+
+.. code:: YAML
+
+    bootstrap:
+        method: barman
+        barman:
+            keep_existing_recovery_conf: true
+            command: patroni_barman_recover
+            api-url: https://barman-host:7480
+            barman-server: my_server
+            ssh-command: ssh postgres@patroni-host
+
+.. note::
+    ``patroni_barman_recover`` requires that you have both Barman and ``pg-backup-api`` configured in the Barman host, so it can execute a remote ``barman recover`` through the backup API.
+    The above example uses a subset of the available parameters. You can get more information running ``patroni_barman_recover --help``.
 
 .. _custom_replica_creation:
 
@@ -77,7 +108,7 @@ scripts to clone a new replica. Those are configured in the ``postgresql`` confi
             command: <command name>
             keep_data: True
             no_params: True
-            no_master: 1
+            no_leader: 1
 
 example: wal_e
 
@@ -89,7 +120,7 @@ example: wal_e
             - basebackup
         wal_e:
             command: patroni_wale_restore
-            no_master: 1
+            no_leader: 1
             envdir: {{WALE_ENV_DIR}}
             use_iam: 1
         basebackup:
@@ -110,6 +141,25 @@ example: pgbackrest
         basebackup:
             max-rate: '100M'
 
+example: Barman
+
+.. code:: YAML
+
+    postgresql:
+        create_replica_methods:
+            - barman
+            - basebackup
+        barman:
+            command: patroni_barman_recover
+            api-url: https://barman-host:7480
+            barman-server: my_server
+            ssh-command: ssh postgres@patroni-host
+        basebackup:
+            max-rate: '100M'
+
+.. note::
+    ``patroni_barman_recover`` requires that you have both Barman and ``pg-backup-api`` configured in the Barman host, so it can execute a remote ``barman recover`` through the backup API.
+    The above example uses a subset of the available parameters. You can get more information running ``patroni_barman_recover --help``.
 
 The ``create_replica_methods`` defines available replica creation methods and the order of executing them. Patroni will
 stop on the first one that returns 0. Each method should define a separate section in the configuration file, listing the command
@@ -126,7 +176,7 @@ to execute and any custom parameters that should be passed to that command. All
     Connection string to connect to the cluster member to clone from (primary or other replica). The user in the
     connection string can execute SQL and replication protocol commands.
 
-A special ``no_master`` parameter, if defined, allows Patroni to call the replica creation method even if there is no
+A special ``no_leader`` parameter, if defined, allows Patroni to call the replica creation method even if there is no
 running leader or replicas. In that case, an empty string will be passed in a connection string. This is useful for
 restoring the formerly running cluster from the binary backup.
 
@@ -191,7 +241,7 @@ There is no further relationship between the standby cluster and the primary
 cluster it replicates from, in particular, they must not share the same DCS
 scope if they use the same DCS. They do not know anything else from each other
 apart from replication information. Also, the standby cluster is not being
-displayed in ``patronictl list`` or ``patronictl topology`` output on the
+displayed in :ref:`patronictl_list` or :ref:`patronictl_topology` output on the
 primary cluster.
 
 For the sake of flexibility, you can specify methods of creating a replica and

docs/replication_modes.rst

@@ -49,7 +49,7 @@ on at least two nodes, enable ``synchronous_mode_strict`` in addition to the
 ``synchronous_mode``. This parameter prevents Patroni from switching off the
 synchronous replication on the primary when no synchronous standby candidates
 are available. As a downside, the primary is not be available for writes
-(unless the Postgres transaction explicitly turns of ``synchronous_mode``),
+(unless the Postgres transaction explicitly turns off ``synchronous_mode``),
 blocking all client write requests until at least one synchronous replica comes
 up.
 

docs/rest_api.rst

@@ -3,7 +3,7 @@
 Patroni REST API
 ================
 
-Patroni has a rich REST API, which is used by Patroni itself during the leader race, by the ``patronictl`` tool in order to perform failovers/switchovers/reinitialize/restarts/reloads, by HAProxy or any other kind of load balancer to perform HTTP health checks, and of course could also be used for monitoring. Below you will find the list of Patroni REST API endpoints.
+Patroni has a rich REST API, which is used by Patroni itself during the leader race, by the :ref:`patronictl` tool in order to perform failovers/switchovers/reinitialize/restarts/reloads, by HAProxy or any other kind of load balancer to perform HTTP health checks, and of course could also be used for monitoring. Below you will find the list of Patroni REST API endpoints.
 
 Health check endpoints
 ----------------------
@@ -12,7 +12,6 @@ For all health check ``GET`` requests Patroni returns a JSON document with the s
 - The following requests to Patroni REST API will return HTTP status code **200** only when the Patroni node is running as the primary with leader lock:
 
   - ``GET /``
-  - ``GET /master``
   - ``GET /primary``
   - ``GET /read-write``
 
@@ -31,9 +30,9 @@ For all health check ``GET`` requests Patroni returns a JSON document with the s
 
 - ``GET /replica?tag_key1=value1&tag_key2=value2``: replica check endpoint. In addition, It will also check for user defined tags ``key1`` and ``key2`` and their respective values in the **tags** section of the yaml configuration management. If the tag isn't defined for an instance, or if the value in the yaml configuration doesn't match the querying value, it will return HTTP Status Code 503.
 
- In the following requests, since we are checking for the leader or standby-leader status, Patroni doesn't apply any of the user defined tags and they will be ignored.
+  In the following requests, since we are checking for the leader or standby-leader status, Patroni doesn't apply any of the user defined tags and they will be ignored.
+
   - ``GET /?tag_key1=value1&tag_key2=value2``
-  - ``GET /master?tag_key1=value1&tag_key2=value2``
   - ``GET /leader?tag_key1=value1&tag_key2=value2``
   - ``GET /primary?tag_key1=value1&tag_key2=value2``
   - ``GET /read-write?tag_key1=value1&tag_key2=value2``
@@ -93,26 +92,263 @@ Monitoring endpoint
 
 The ``GET /patroni`` is used by Patroni during the leader race. It also could be used by your monitoring system. The JSON document produced by this endpoint has the same structure as the JSON produced by the health check endpoints.
 
+**Example:** A healthy cluster
+
 .. code-block:: bash
 
     $ curl -s http://localhost:8008/patroni | jq .
     {
       "state": "running",
-      "postmaster_start_time": "2019-09-24 09:22:32.555 CEST",
+      "postmaster_start_time": "2023-08-18 11:03:37.966359+00:00",
       "role": "master",
-      "server_version": 110005,
-      "cluster_unlocked": false,
+      "server_version": 150004,
       "xlog": {
-        "location": 25624640
+        "location": 67395656
       },
-      "timeline": 3,
-      "database_system_identifier": "6739877027151648096",
+      "timeline": 1,
+      "replication": [
+        {
+          "usename": "replicator",
+          "application_name": "patroni2",
+          "client_addr": "10.89.0.6",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        },
+        {
+          "usename": "replicator",
+          "application_name": "patroni3",
+          "client_addr": "10.89.0.2",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        }
+      ],
+      "dcs_last_seen": 1692356718,
+      "tags": {
+        "clonefrom": true
+      },
+      "database_system_identifier": "7268616322854375442",
       "patroni": {
-        "version": "1.6.0",
-        "scope": "batman"
+        "version": "3.1.0",
+        "scope": "demo",
+        "name": "patroni1"
       }
     }
 
+**Example:** An unlocked cluster
+
+.. code-block:: bash
+
+    $ curl -s http://localhost:8008/patroni  | jq .
+    {
+      "state": "running",
+      "postmaster_start_time": "2023-08-18 11:09:08.615242+00:00",
+      "role": "replica",
+      "server_version": 150004,
+      "xlog": {
+        "received_location": 67419744,
+        "replayed_location": 67419744,
+        "replayed_timestamp": null,
+        "paused": false
+      },
+      "timeline": 1,
+      "replication": [
+        {
+          "usename": "replicator",
+          "application_name": "patroni2",
+          "client_addr": "10.89.0.6",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        },
+        {
+          "usename": "replicator",
+          "application_name": "patroni3",
+          "client_addr": "10.89.0.2",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        }
+      ],
+      "cluster_unlocked": true,
+      "dcs_last_seen": 1692356928,
+      "tags": {
+        "clonefrom": true
+      },
+      "database_system_identifier": "7268616322854375442",
+      "patroni": {
+        "version": "3.1.0",
+        "scope": "demo",
+        "name": "patroni1"
+      }
+    }
+
+**Example:** An unlocked cluster with :ref:`DCS failsafe mode <dcs_failsafe_mode>` enabled
+
+.. code-block:: bash
+
+    $ curl -s http://localhost:8008/patroni  | jq .
+    {
+      "state": "running",
+      "postmaster_start_time": "2023-08-18 11:09:08.615242+00:00",
+      "role": "replica",
+      "server_version": 150004,
+      "xlog": {
+        "location": 67420024
+      },
+      "timeline": 1,
+      "replication": [
+        {
+          "usename": "replicator",
+          "application_name": "patroni2",
+          "client_addr": "10.89.0.6",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        },
+        {
+          "usename": "replicator",
+          "application_name": "patroni3",
+          "client_addr": "10.89.0.2",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        }
+      ],
+      "cluster_unlocked": true,
+      "failsafe_mode_is_active": true,
+      "dcs_last_seen": 1692356928,
+      "tags": {
+        "clonefrom": true
+      },
+      "database_system_identifier": "7268616322854375442",
+      "patroni": {
+        "version": "3.1.0",
+        "scope": "demo",
+        "name": "patroni1"
+      }
+    }
+
+**Example:** A cluster with the :ref:`pause mode <pause>` enabled
+
+.. code-block:: bash
+
+    $ curl -s http://localhost:8008/patroni  | jq .
+    {
+      "state": "running",
+      "postmaster_start_time": "2023-08-18 11:09:08.615242+00:00",
+      "role": "replica",
+      "server_version": 150004,
+      "xlog": {
+        "location": 67420024
+      },
+      "timeline": 1,
+      "replication": [
+        {
+          "usename": "replicator",
+          "application_name": "patroni2",
+          "client_addr": "10.89.0.6",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        },
+        {
+          "usename": "replicator",
+          "application_name": "patroni3",
+          "client_addr": "10.89.0.2",
+          "state": "streaming",
+          "sync_state": "async",
+          "sync_priority": 0
+        }
+      ],
+      "pause": true,
+      "dcs_last_seen": 1692356928,
+      "tags": {
+        "clonefrom": true
+      },
+      "database_system_identifier": "7268616322854375442",
+      "patroni": {
+        "version": "3.1.0",
+        "scope": "demo",
+        "name": "patroni1"
+      }
+    }
+
+Retrieve the Patroni metrics in Prometheus format through the ``GET /metrics`` endpoint.
+
+.. code-block:: bash
+
+	$ curl http://localhost:8008/metrics
+	
+	# HELP patroni_version Patroni semver without periods. \
+	# TYPE patroni_version gauge
+	patroni_version{scope="batman",name="patroni1"} 020103
+	# HELP patroni_postgres_running Value is 1 if Postgres is running, 0 otherwise.
+	# TYPE patroni_postgres_running gauge
+	patroni_postgres_running{scope="batman",name="patroni1"} 1
+	# HELP patroni_postmaster_start_time Epoch seconds since Postgres started.
+	# TYPE patroni_postmaster_start_time gauge
+	patroni_postmaster_start_time{scope="batman",name="patroni1"} 1657656955.179243
+	# HELP patroni_master Value is 1 if this node is the leader, 0 otherwise.
+	# TYPE patroni_master gauge
+	patroni_master{scope="batman",name="patroni1"} 1
+	# HELP patroni_primary Value is 1 if this node is the leader, 0 otherwise.
+	# TYPE patroni_primary gauge
+	patroni_primary{scope="batman",name="patroni1"} 1
+	# HELP patroni_xlog_location Current location of the Postgres transaction log, 0 if this node is not the leader.
+	# TYPE patroni_xlog_location counter
+	patroni_xlog_location{scope="batman",name="patroni1"} 22320573386952
+	# HELP patroni_standby_leader Value is 1 if this node is the standby_leader, 0 otherwise.
+	# TYPE patroni_standby_leader gauge
+	patroni_standby_leader{scope="batman",name="patroni1"} 0
+	# HELP patroni_replica Value is 1 if this node is a replica, 0 otherwise.
+	# TYPE patroni_replica gauge
+	patroni_replica{scope="batman",name="patroni1"} 0
+	# HELP patroni_sync_standby Value is 1 if this node is a sync standby replica, 0 otherwise.
+	# TYPE patroni_sync_standby gauge
+	patroni_sync_standby{scope="batman",name="patroni1"} 0
+	# HELP patroni_xlog_received_location Current location of the received Postgres transaction log, 0 if this node is not a replica.
+	# TYPE patroni_xlog_received_location counter
+	patroni_xlog_received_location{scope="batman",name="patroni1"} 0
+	# HELP patroni_xlog_replayed_location Current location of the replayed Postgres transaction log, 0 if this node is not a replica.
+	# TYPE patroni_xlog_replayed_location counter
+	patroni_xlog_replayed_location{scope="batman",name="patroni1"} 0
+	# HELP patroni_xlog_replayed_timestamp Current timestamp of the replayed Postgres transaction log, 0 if null.
+	# TYPE patroni_xlog_replayed_timestamp gauge
+	patroni_xlog_replayed_timestamp{scope="batman",name="patroni1"} 0
+	# HELP patroni_xlog_paused Value is 1 if the Postgres xlog is paused, 0 otherwise.
+	# TYPE patroni_xlog_paused gauge
+	patroni_xlog_paused{scope="batman",name="patroni1"} 0
+	# HELP patroni_postgres_streaming Value is 1 if Postgres is streaming, 0 otherwise.
+	# TYPE patroni_postgres_streaming gauge
+	patroni_postgres_streaming{scope="batman",name="patroni1"} 1
+	# HELP patroni_postgres_in_archive_recovery Value is 1 if Postgres is replicating from archive, 0 otherwise.
+	# TYPE patroni_postgres_in_archive_recovery gauge
+	patroni_postgres_in_archive_recovery{scope="batman",name="patroni1"} 0
+	# HELP patroni_postgres_server_version Version of Postgres (if running), 0 otherwise.
+	# TYPE patroni_postgres_server_version gauge
+	patroni_postgres_server_version{scope="batman",name="patroni1"} 140004
+	# HELP patroni_cluster_unlocked Value is 1 if the cluster is unlocked, 0 if locked.
+	# TYPE patroni_cluster_unlocked gauge
+	patroni_cluster_unlocked{scope="batman",name="patroni1"} 0
+	# HELP patroni_postgres_timeline Postgres timeline of this node (if running), 0 otherwise.
+	# TYPE patroni_postgres_timeline counter
+	patroni_failsafe_mode_is_active{scope="batman",name="patroni1"} 0
+	# HELP patroni_postgres_timeline Postgres timeline of this node (if running), 0 otherwise.
+	# TYPE patroni_postgres_timeline counter
+	patroni_postgres_timeline{scope="batman",name="patroni1"} 24
+	# HELP patroni_dcs_last_seen Epoch timestamp when DCS was last contacted successfully by Patroni.
+	# TYPE patroni_dcs_last_seen gauge
+	patroni_dcs_last_seen{scope="batman",name="patroni1"} 1677658321
+	# HELP patroni_pending_restart Value is 1 if the node needs a restart, 0 otherwise.
+	# TYPE patroni_pending_restart gauge
+	patroni_pending_restart{scope="batman",name="patroni1"} 1
+	# HELP patroni_is_paused Value is 1 if auto failover is disabled, 0 otherwise.
+	# TYPE patroni_is_paused gauge
+	patroni_is_paused{scope="batman",name="patroni1"} 1
+
+
 Cluster status endpoints
 ------------------------
 
@@ -124,24 +360,24 @@ Cluster status endpoints
     {
       "members": [
         {
-          "name": "postgresql0",
-          "host": "127.0.0.1",
-          "port": 5432,
+          "name": "patroni1",
           "role": "leader",
           "state": "running",
-          "api_url": "http://127.0.0.1:8008/patroni",
+          "api_url": "http://10.89.0.4:8008/patroni",
+          "host": "10.89.0.4",
+          "port": 5432,
           "timeline": 5,
           "tags": {
             "clonefrom": true
           }
         },
         {
-          "name": "postgresql1",
-          "host": "127.0.0.1",
-          "port": 5433,
+          "name": "patroni2",
           "role": "replica",
-          "state": "running",
-          "api_url": "http://127.0.0.1:8009/patroni",
+          "state": "streaming",
+          "api_url": "http://10.89.0.6:8008/patroni",
+          "host": "10.89.0.6",
+          "port": 5433,
           "timeline": 5,
           "tags": {
             "clonefrom": true
@@ -149,9 +385,11 @@ Cluster status endpoints
           "lag": 0
         }
       ],
+      "scope": "demo",
       "scheduled_switchover": {
-        "at": "2019-09-24T10:36:00+02:00",
-        "from": "postgresql0"
+        "at": "2023-09-24T10:36:00+02:00",
+        "from": "patroni1",
+        "to": "patroni3"
       }
     }
 
@@ -188,6 +426,7 @@ Cluster status endpoints
       ]
     ]
 
+.. _config_endpoint:
 
 Config endpoint
 ---------------
@@ -196,7 +435,7 @@ Config endpoint
 
 .. code-block:: bash
 
-	$ curl -s localhost:8008/config | jq .
+	$ curl -s http://localhost:8008/config | jq .
 	{
 	  "ttl": 30,
 	  "loop_wait": 10,
@@ -207,7 +446,6 @@ Config endpoint
 	    "use_pg_rewind": true,
 	    "parameters": {
 	      "hot_standby": "on",
-	      "wal_log_hints": "on",
 	      "wal_level": "hot_standby",
 	      "max_wal_senders": 5,
 	      "max_replication_slots": 5,
@@ -234,7 +472,6 @@ Config endpoint
 	    "use_pg_rewind": true,
 	    "parameters": {
 	      "hot_standby": "on",
-	      "wal_log_hints": "on",
 	      "wal_level": "hot_standby",
 	      "max_wal_senders": 5,
 	      "max_replication_slots": 5,
@@ -258,8 +495,9 @@ Let's check that the node processed this configuration. First of all it should s
 	    "location": 2197818976
 	  },
 	  "patroni": {
+	    "version": "1.0",
 	    "scope": "batman",
-	    "version": "1.0"
+	    "name": "patroni1"
 	  },
 	  "state": "running",
 	  "role": "master",
@@ -287,7 +525,6 @@ If you want to remove (reset) some setting just patch it with ``null``:
 	      "hot_standby": "on",
 	      "unix_socket_directories": ".",
 	      "wal_level": "hot_standby",
-	      "wal_log_hints": "on",
 	      "max_wal_senders": 5,
 	      "max_replication_slots": 5
 	    }
@@ -301,7 +538,7 @@ The above call removes ``postgresql.parameters.max_connections`` from the dynami
 .. code-block:: bash
 
 	$ curl -s -XPUT -d \
-		'{"maximum_lag_on_failover":1048576,"retry_timeout":10,"postgresql":{"use_slots":true,"use_pg_rewind":true,"parameters":{"hot_standby":"on","wal_log_hints":"on","wal_level":"hot_standby","unix_socket_directories":".","max_wal_senders":5}},"loop_wait":3,"ttl":20}' \
+		'{"maximum_lag_on_failover":1048576,"retry_timeout":10,"postgresql":{"use_slots":true,"use_pg_rewind":true,"parameters":{"hot_standby":"on","wal_level":"hot_standby","unix_socket_directories":".","max_wal_senders":5}},"loop_wait":3,"ttl":20}' \
 		http://localhost:8008/config | jq .
 	{
 	  "ttl": 20,
@@ -313,7 +550,6 @@ The above call removes ``postgresql.parameters.max_connections`` from the dynami
 	      "hot_standby": "on",
 	      "unix_socket_directories": ".",
 	      "wal_level": "hot_standby",
-	      "wal_log_hints": "on",
 	      "max_wal_senders": 5
 	    },
 	    "use_pg_rewind": true
@@ -325,41 +561,114 @@ The above call removes ``postgresql.parameters.max_connections`` from the dynami
 Switchover and failover endpoints
 ---------------------------------
 
-``POST /switchover`` or ``POST /failover``. These endpoints are very similar to each other. There are a couple of minor differences though:
+.. _switchover_api:
 
-1. The failover endpoint allows to perform a manual failover when there are no healthy nodes, but at the same time it will not allow you to schedule a switchover.
+Switchover
+^^^^^^^^^^
 
-2. The switchover endpoint is the opposite. It works only when the cluster is healthy (there is a leader) and allows to schedule a switchover at a given time.
+``/switchover`` endpoint only works when the cluster is healthy (there is a leader). It also allows to schedule a switchover at a given time.
 
+When calling ``/switchover`` endpoint a candidate can be specified but is not required, in contrast to ``/failover`` endpoint. If a candidate is not provided, all the eligible nodes of the cluster will participate in the leader race after the leader stepped down.
 
-In the JSON body of the ``POST`` request you must specify at least the ``leader`` or ``candidate`` fields and optionally the ``scheduled_at`` field if you want to schedule a switchover at a specific time.
+In the JSON body of the ``POST`` request you must specify the ``leader`` field. The ``candidate`` and the ``scheduled_at`` fields are optional and can be used to schedule a switchover at a specific time.
 
+Depending on the situation, requests might return different HTTP status codes and bodies. Status code **200** is returned when the switchover or failover successfully completed. If the switchover was successfully scheduled, Patroni will return HTTP status code **202**. In case something went wrong, the error status code (one of **400**, **412**, or **503**) will be returned with some details in the response body.
 
-Example: perform a failover to the specific node:
+``DELETE /switchover`` can be used to delete the currently scheduled switchover.
+
+**Example:** perform a switchover to any healthy standby
 
 .. code-block:: bash
 
-    $ curl -s http://localhost:8009/failover -XPOST -d '{"candidate":"postgresql1"}'
-    Successfully failed over to "postgresql1"
+	$ curl -s http://localhost:8008/switchover -XPOST -d '{"leader":"postgresql1"}'
+	Successfully switched over to "postgresql2"
 
 
-Example: schedule a switchover from the leader to any other healthy replica in the cluster at a specific time:
+**Example:** perform a switchover to a specific node
 
 .. code-block:: bash
 
-    $ curl -s http://localhost:8008/switchover -XPOST -d \
-	    '{"leader":"postgresql0","scheduled_at":"2019-09-24T12:00+00"}'
-    Switchover scheduled
+	$ curl -s http://localhost:8008/switchover -XPOST -d \
+		'{"leader":"postgresql1","candidate":"postgresql2"}'
+	Successfully switched over to "postgresql2"
 
 
-Depending on the situation the request might finish with a different HTTP status code and body. The status code **200** is returned when the switchover or failover successfully completed. If the switchover was successfully scheduled, Patroni will return HTTP status code **202**. In case something went wrong, the error status code (one of **400**, **412** or **503**) will be returned with some details in the response body. For more information please check the source code of ``patroni/api.py:do_POST_failover()`` method.
+**Example:** schedule a switchover from the leader to any other healthy standby in the cluster at a specific time.
 
-- ``DELETE /switchover``: delete the scheduled switchover
+.. code-block:: bash
 
-The ``POST /switchover`` and ``POST failover`` endpoints are used by ``patronictl switchover`` and ``patronictl failover``, respectively.
-The ``DELETE /switchover`` is used by ``patronictl flush <cluster-name> switchover``.
+	$ curl -s http://localhost:8008/switchover -XPOST -d \
+		'{"leader":"postgresql0","scheduled_at":"2019-09-24T12:00+00"}'
+	Switchover scheduled
 
 
+Failover
+^^^^^^^^
+
+``/failover`` endpoint can be used to perform a manual failover when there are no healthy nodes (e.g. to an asynchronous standby if all synchronous standbys are not healthy enough to promote). However there is no requirement for a cluster not to have leader - failover can also be run on a healthy cluster.
+
+In the JSON body of the ``POST`` request you must specify the ``candidate`` field. If the ``leader`` field is specified, a switchover is triggered instead.
+
+**Example:**
+
+.. code-block:: bash
+
+	$ curl -s http://localhost:8008/failover -XPOST -d '{"candidate":"postgresql1"}'
+	Successfully failed over to "postgresql1"
+
+.. warning::
+	:ref:`Be very careful <failover_healthcheck>` when using this endpoint, as this can cause data loss in certain situations. In most cases, :ref:`the switchover endpoint <switchover_api>` satisfies the administrator's needs. 
+
+
+``POST /switchover`` and ``POST /failover`` endpoints are used by :ref:`patronictl_switchover` and :ref:`patronictl_failover`, respectively.
+
+``DELETE /switchover`` is used by :ref:`patronictl flush cluster-name switchover <patronictl_flush_parameters>`.
+
+.. list-table:: Failover/Switchover comparison
+   :widths: 25 25 25
+   :header-rows: 1
+
+   * -
+     - Failover
+     - Switchover
+   * - Requires leader specified
+     - no
+     - yes
+   * - Requires candidate specified
+     - yes
+     - no
+   * - Can be run in pause
+     - yes
+     - yes (only to a specific candidate)
+   * - Can be scheduled
+     - no
+     - yes (if not in pause)
+
+.. _failover_healthcheck:
+
+Healthy standby
+^^^^^^^^^^^^^^^
+
+There are a couple of checks that a member of a cluster should pass to be able to participate in the leader race during a switchover or to become a leader as a failover/switchover candidate:
+
+- be reachable via Patroni API;
+- not have ``nofailover`` tag set to ``true``;
+- have watchdog fully functional (if required by the configuration);
+- in case of a switchover in a healthy cluster or an automatic failover, not exceed maximum replication lag (``maximum_lag_on_failover`` :ref:`configuration parameter <dynamic_configuration>`);
+- in case of a switchover in a healthy cluster or an automatic failover, not have a timeline number smaller than the cluster timeline if ``check_timeline`` :ref:`configuration parameter <dynamic_configuration>` is set to ``true``;
+- in :ref:`synchronous mode <synchronous_mode>`:
+
+  - In case of a switchover (both with and without a candidate): be listed in the ``/sync`` key members;
+  - For a failover in both healthy and unhealthy clusters, this check is omitted.
+
+.. warning::
+    In case of a manual failover in a cluster without a leader, a candidate will be allowed to promote even if:
+	- it is not in the ``/sync`` key members when synchronous mode is enabled;
+	- its lag exceeds the maximum replication lag allowed;
+	- it has the timeline number smaller than the last known cluster timeline.
+
+.. _restart_endpoint:
+
 Restart endpoint
 ----------------
 
@@ -368,20 +677,21 @@ Restart endpoint
   - **restart_pending**: boolean, if set to ``true`` Patroni will restart PostgreSQL only when restart is pending in order to apply some changes in the PostgreSQL config.
   - **role**: perform restart only if the current role of the node matches with the role from the POST request.
   - **postgres_version**: perform restart only if the current version of postgres is smaller than specified in the POST request.
-  - **timeout**: how long we should wait before PostgreSQL starts accepting connections. Overrides ``master_start_timeout``.
+  - **timeout**: how long we should wait before PostgreSQL starts accepting connections. Overrides ``primary_start_timeout``.
   - **schedule**: timestamp with time zone, schedule the restart somewhere in the future.
 
 - ``DELETE /restart``: delete the scheduled restart
 
-``POST /restart`` and ``DELETE /restart`` endpoints are used by ``patronictl restart`` and ``patronictl flush <cluster-name> restart`` respectively.
+``POST /restart`` and ``DELETE /restart`` endpoints are used by :ref:`patronictl_restart` and :ref:`patronictl flush cluster-name restart <patronictl_flush_parameters>` respectively.
 
+.. _reload_endpoint:
 
 Reload endpoint
 ---------------
 
-The ``POST /reload`` call will order Patroni to re-read and apply the configuration file. This is the equivalent of sending the ``SIGHUP`` signal to the Patroni process. In case you changed some of the Postgres parameters which require a restart (like **shared_buffers**), you still have to explicitly do the restart of Postgres by either calling the ``POST /restart`` endpoint or with the help of ``patronictl restart``.
+The ``POST /reload`` call will order Patroni to re-read and apply the configuration file. This is the equivalent of sending the ``SIGHUP`` signal to the Patroni process. In case you changed some of the Postgres parameters which require a restart (like **shared_buffers**), you still have to explicitly do the restart of Postgres by either calling the ``POST /restart`` endpoint or with the help of :ref:`patronictl_restart`.
 
-The reload endpoint is used by ``patronictl reload``.
+The reload endpoint is used by :ref:`patronictl_reload`.
 
 
 Reinitialize endpoint
@@ -391,4 +701,4 @@ Reinitialize endpoint
 
 The call might fail if Patroni is in a loop trying to recover (restart) a failed Postgres. In order to overcome this problem one can specify ``{"force":true}`` in the request body.
 
-The reinitialize endpoint is used by ``patronictl reinit``.
+The reinitialize endpoint is used by :ref:`patronictl_reinit`.

docs/security.rst

@@ -9,11 +9,11 @@ A Patroni cluster has two interfaces to be protected from unauthorized access: t
 Protecting DCS
 ==============
 
-Patroni and patronictl both store and retrieve data to/from the DCS. 
+Patroni and :ref:`patronictl` both store and retrieve data to/from the DCS.
 
 Despite DCS doesn't contain any sensitive information, it allows changing some of Patroni/Postgres configuration. Therefore the very first thing that should be protected is DCS itself.
 
-The details of protection depend on the type of DCS used. The authentication and encryption parameters (tokens/basic-auth/client certificates) for the supported types of DCS are covered in :ref:`SETTINGS <bootstrap_settings>` 
+The details of protection depend on the type of DCS used. The authentication and encryption parameters (tokens/basic-auth/client certificates) for the supported types of DCS are covered in :ref:`settings <yaml_configuration>`.
 
 The general recommendation is to enable TLS for all DCS communication.
 
@@ -22,7 +22,7 @@ Protecting the REST API
 
 Protecting the REST API is a more complicated task.
 
-The Patroni REST API is used by Patroni itself during the leader race, by the ``patronictl`` tool in order to perform failovers/switchovers/reinitialize/restarts/reloads, by HAProxy or any other kind of load balancer to perform HTTP health checks, and of course could also be used for monitoring. 
+The Patroni REST API is used by Patroni itself during the leader race, by the :ref:`patronictl` tool in order to perform failovers/switchovers/reinitialize/restarts/reloads, by HAProxy or any other kind of load balancer to perform HTTP health checks, and of course could also be used for monitoring.
 
 From the point of view of security, REST API contains safe (``GET`` requests, only retrieve information) and unsafe (``PUT``, ``POST``, ``PATCH`` and ``DELETE`` requests, change the state of nodes) endpoints.
 
@@ -32,6 +32,6 @@ When TLS for the REST API is enabled and a PKI is established, mutual authentica
 
 The ``restapi`` section parameters enable TLS client authentication to the server. Depending on the value of the ``verify_client`` parameter, the API server requires a successful client certificate verification for both safe and unsafe API calls (``verify_client: required``), or only for unsafe API calls (``verify_client: optional``), or for no API calls (``verify_client: none``).
 
-The ``ctl`` section parameters enable TLS server authentication to the client (the ``patronictl`` tool which uses the same config as patroni). Set ``insecure: true`` to disable the server certificate verification by the client. See :ref:`SETTINGS <patronictl_settings>` for a detailed description of the TLS client parameters.
+The ``ctl`` section parameters enable TLS server authentication to the client (the :ref:`patronictl` tool which uses the same config as patroni). Set ``insecure: true`` to disable the server certificate verification by the client. See :ref:`settings <patronictl_settings>` for a detailed description of the TLS client parameters.
 
 Protecting the PostgreSQL database proper from unauthorized access is beyond the scope of this document and is covered in https://www.postgresql.org/docs/current/client-authentication.html

docs/yaml_configuration.rst

@@ -0,0 +1,413 @@
+.. _yaml_configuration:
+
+============================
+YAML Configuration Settings
+============================
+
+
+Global/Universal
+----------------
+-  **name**: the name of the host. Must be unique for the cluster.
+-  **namespace**: path within the configuration store where Patroni will keep information about the cluster. Default value: "/service"
+-  **scope**: cluster name
+
+.. _log_settings:
+
+Log
+---
+-  **type**: sets the format of logs. Can be either **plain** or **json**. To use **json** format, you must have the :ref:`jsonlogger <extras>` installed. The default value is **plain**.
+-  **level**: sets the general logging level. Default value is **INFO** (see `the docs for Python logging <https://docs.python.org/3.6/library/logging.html#levels>`_)
+-  **traceback\_level**: sets the level where tracebacks will be visible. Default value is **ERROR**. Set it to **DEBUG** if you want to see tracebacks only if you enable **log.level=DEBUG**.
+-  **format**: sets the log formatting string. If the log type is **plain**, the log format should be a string. Refer to
+   `the LogRecord attributes <https://docs.python.org/3.6/library/logging.html#logrecord-attributes>`_ for
+   available attributes. If the log type is **json**, the log format can be a list in addition to a string. Each list
+   item should correspond to LogRecord attributes. Be cautious that only the field name is required, and the **%(**
+   and **)** should be omitted. If you wish to print a log field with a different key name, use a dictionary where
+   the dictionary key is the log field, and the value is the name of the field you want to be printed in the log.
+   Default value is **%(asctime)s %(levelname)s: %(message)s**
+-  **dateformat**: sets the datetime formatting string. (see the `formatTime() documentation <https://docs.python.org/3.6/library/logging.html#logging.Formatter.formatTime>`_)
+-  **static_fields**: add additional fields to the log. This option is only available when the log type is set to **json**.
+-  **max\_queue\_size**: Patroni is using two-step logging. Log records are written into the in-memory queue and there is a separate thread which pulls them from the queue and writes to stderr or file. The maximum size of the internal queue is limited by default by **1000** records, which is enough to keep logs for the past 1h20m.
+-  **dir**: Directory to write application logs to. The directory must exist and be writable by the user executing Patroni. If you set this value, the application will retain 4 25MB logs by default. You can tune those retention values with `file_num` and `file_size` (see below).
+-  **file\_num**: The number of application logs to retain.
+-  **file\_size**: Size of patroni.log file (in bytes) that triggers a log rolling.
+-  **loggers**: This section allows redefining logging level per python module
+
+   -  **patroni.postmaster: WARNING**
+   -  **urllib3: DEBUG**
+
+Here is an example of how to config patroni to log in json format.
+
+.. code:: YAML
+
+   log:
+      type: json
+      format:
+         - message
+         - module
+         - asctime: '@timestamp'
+         - levelname: level
+      static_fields:
+         app: patroni
+
+.. _bootstrap_settings:
+
+Bootstrap configuration
+-----------------------
+
+.. note::
+    Once Patroni has initialized the cluster for the first time and settings have been stored in the DCS, all future
+    changes to the ``bootstrap.dcs`` section of the YAML configuration will not take any effect! If you want to change
+    them please use either :ref:`patronictl_edit_config` or the Patroni :ref:`REST API <rest_api>`.
+
+-  **bootstrap**:
+
+   -  **dcs**: This section will be written into `/<namespace>/<scope>/config` of the given configuration store after initializing the new cluster. The global dynamic configuration for the cluster. You can put any of the parameters described in the :ref:`Dynamic Configuration settings <dynamic_configuration>` under ``bootstrap.dcs`` and after Patroni has initialized (bootstrapped) the new cluster, it will write this section into `/<namespace>/<scope>/config` of the configuration store.
+   -  **method**: custom script to use for bootstrapping this cluster.
+
+      See :ref:`custom bootstrap methods documentation <custom_bootstrap>` for details.
+      When ``initdb`` is specified revert to the default ``initdb`` command. ``initdb`` is also triggered when no ``method``
+      parameter is present in the configuration file.
+   -  **initdb**: (optional) list options to be passed on to initdb.
+
+      -  **- data-checksums**: Must be enabled when pg_rewind is needed on 9.3.
+      -  **- encoding: UTF8**: default encoding for new databases.
+      -  **- locale: UTF8**: default locale for new databases.
+   -  **post\_bootstrap** or **post\_init**: An additional script that will be executed after initializing the cluster. The script receives a connection string URL (with the cluster superuser as a user name). The PGPASSFILE variable is set to the location of pgpass file.
+
+.. _citus_settings:
+
+Citus
+-----
+Enables integration Patroni with `Citus <https://docs.citusdata.com>`__. If configured, Patroni will take care of registering Citus worker nodes on the coordinator. You can find more information about Citus support :ref:`here <citus>`.
+
+-  **group**: the Citus group id, integer. Use ``0`` for coordinator and ``1``, ``2``, etc... for workers
+-  **database**: the database where ``citus`` extension should be created. Must be the same on the coordinator and all workers. Currently only one database is supported.
+
+.. _consul_settings:
+
+Consul
+------
+Most of the parameters are optional, but you have to specify one of the **host** or **url**
+
+-  **host**: the host:port for the Consul local agent.
+-  **url**: url for the Consul local agent, in format: http(s)://host:port.
+-  **port**: (optional) Consul port.
+-  **scheme**: (optional) **http** or **https**, defaults to **http**.
+-  **token**: (optional) ACL token.
+-  **verify**: (optional) whether to verify the SSL certificate for HTTPS requests.
+-  **cacert**: (optional) The ca certificate. If present it will enable validation.
+-  **cert**: (optional) file with the client certificate.
+-  **key**: (optional) file with the client key. Can be empty if the key is part of **cert**.
+-  **dc**: (optional) Datacenter to communicate with. By default the datacenter of the host is used.
+-  **consistency**: (optional) Select consul consistency mode. Possible values are ``default``, ``consistent``, or ``stale`` (more details in `consul API reference <https://www.consul.io/api/features/consistency.html/>`__)
+-  **checks**: (optional) list of Consul health checks used for the session. By default an empty list is used.
+-  **register\_service**: (optional) whether or not to register a service with the name defined by the scope parameter and the tag master, primary, replica, or standby-leader depending on the node's role. Defaults to **false**.
+-  **service\_tags**: (optional) additional static tags to add to the Consul service apart from the role (``master``/``primary``/``replica``/``standby-leader``). By default an empty list is used.
+-  **service\_check\_interval**: (optional) how often to perform health check against registered url. Defaults to '5s'.
+-  **service\_check\_tls\_server\_name**: (optional) overide SNI host when connecting via TLS, see also `consul agent check API reference <https://www.consul.io/api-docs/agent/check#tlsservername>`__.
+
+The ``token`` needs to have the following ACL permissions:
+
+::
+
+    service_prefix "${scope}" {
+        policy = "write"
+    }
+    key_prefix "${namespace}/${scope}" {
+        policy = "write"
+    }
+    session_prefix "" {
+        policy = "write"
+    }
+
+Etcd
+----
+Most of the parameters are optional, but you have to specify one of the **host**, **hosts**, **url**, **proxy** or **srv**
+
+-  **host**: the host:port for the etcd endpoint.
+-  **hosts**: list of etcd endpoint in format host1:port1,host2:port2,etc... Could be a comma separated string or an actual yaml list.
+-  **use\_proxies**: If this parameter is set to true, Patroni will consider **hosts** as a list of proxies and will not perform a topology discovery of etcd cluster.
+-  **url**: url for the etcd.
+-  **proxy**: proxy url for the etcd. If you are connecting to the etcd using proxy, use this parameter instead of **url**.
+-  **srv**: Domain to search the SRV record(s) for cluster autodiscovery. Patroni will try to query these SRV service names for specified domain (in that order until first success): ``_etcd-client-ssl``, ``_etcd-client``, ``_etcd-ssl``, ``_etcd``, ``_etcd-server-ssl``, ``_etcd-server``. If SRV records for ``_etcd-server-ssl`` or ``_etcd-server`` are retrieved then ETCD peer protocol is used do query ETCD for available members. Otherwise hosts from SRV records will be used.
+-  **srv\_suffix**: Configures a suffix to the SRV name that is queried during discovery. Use this flag to differentiate between multiple etcd clusters under the same domain. Works only with conjunction with **srv**. For example, if ``srv_suffix: foo`` and ``srv: example.org`` are set, the following DNS SRV query is made:``_etcd-client-ssl-foo._tcp.example.com`` (and so on for every possible ETCD SRV service name).
+-  **protocol**: (optional) http or https, if not specified http is used. If the **url** or **proxy** is specified - will take protocol from them.
+-  **username**: (optional) username for etcd authentication.
+-  **password**: (optional) password for etcd authentication.
+-  **cacert**: (optional) The ca certificate. If present it will enable validation.
+-  **cert**: (optional) file with the client certificate.
+-  **key**: (optional) file with the client key. Can be empty if the key is part of **cert**.
+
+Etcdv3
+------
+If you want that Patroni works with Etcd cluster via protocol version 3, you need to use the ``etcd3`` section in the Patroni configuration file. All configuration parameters are the same as for ``etcd``.
+
+.. warning::
+    Keys created with protocol version 2 are not visible with protocol version 3 and the other way around, therefore it is not possible to switch from ``etcd`` to ``etcd3`` just by updating Patroni config file.
+
+
+ZooKeeper
+----------
+-  **hosts**: List of ZooKeeper cluster members in format: ['host1:port1', 'host2:port2', 'etc...'].
+-  **use_ssl**: (optional) Whether SSL is used or not. Defaults to ``false``. If set to ``false``, all SSL specific parameters are ignored.
+-  **cacert**: (optional) The CA certificate. If present it will enable validation.
+-  **cert**: (optional) File with the client certificate.
+-  **key**: (optional) File with the client key.
+-  **key_password**: (optional) The client key password.
+-  **verify**: (optional) Whether to verify certificate or not. Defaults to ``true``.
+-  **set_acls**: (optional) If set, configure Kazoo to apply a default ACL to each ZNode that it creates. ACLs will assume 'x509' schema and should be specified as a dictionary with the principal as the key and one or more permissions as a list in the value.  Permissions may be one of ``CREATE``, ``READ``, ``WRITE``, ``DELETE`` or ``ADMIN``.  For example, ``set_acls: {CN=principal1: [CREATE, READ], CN=principal2: [ALL]}``.
+-  **auth_data**: (optional) Authentication credentials to use for the connection. Should be a dictionary in the form that `scheme` is the key and `credential` is the value. Defaults to empty dictionary.
+
+.. note::
+    It is required to install ``kazoo>=2.6.0`` to support SSL.
+
+
+Exhibitor
+---------
+-  **hosts**: initial list of Exhibitor (ZooKeeper) nodes in format: 'host1,host2,etc...'. This list updates automatically whenever the Exhibitor (ZooKeeper) cluster topology changes.
+-  **poll\_interval**: how often the list of ZooKeeper and Exhibitor nodes should be updated from Exhibitor.
+-  **port**: Exhibitor port.
+
+.. _kubernetes_settings:
+
+Kubernetes
+----------
+-  **bypass\_api\_service**: (optional) When communicating with the Kubernetes API, Patroni is usually relying on the `kubernetes` service, the address of which is exposed in the pods via the `KUBERNETES_SERVICE_HOST` environment variable. If `bypass_api_service` is set to ``true``, Patroni will resolve the list of API nodes behind the service and connect directly to them.
+-  **namespace**: (optional) Kubernetes namespace where Patroni pod is running. Default value is `default`.
+-  **labels**: Labels in format ``{label1: value1, label2: value2}``. These labels will be used to find existing objects (Pods and either Endpoints or ConfigMaps) associated with the current cluster. Also Patroni will set them on every object (Endpoint or ConfigMap) it creates.
+-  **scope\_label**: (optional) name of the label containing cluster name. Default value is `cluster-name`.
+-  **role\_label**: (optional) name of the label containing role (master or replica or other custom value). Patroni will set this label on the pod it runs in. Default value is ``role``.
+-  **leader\_label\_value**: (optional) value of the pod label when Postgres role is ``master``. Default value is ``master``.
+-  **follower\_label\_value**: (optional) value of the pod label when Postgres role is ``replica``. Default value is ``replica``.
+-  **standby\_leader\_label\_value**: (optional) value of the pod label when Postgres role is ``standby_leader``. Default value is ``master``.
+-  **tmp_\role\_label**: (optional) name of the temporary label containing role (master or replica). Value of this label will always use the default of corresponding role. Set only when necessary.
+-  **use\_endpoints**: (optional) if set to true, Patroni will use Endpoints instead of ConfigMaps to run leader elections and keep cluster state.
+-  **pod\_ip**: (optional) IP address of the pod Patroni is running in. This value is required when `use_endpoints` is enabled and is used to populate the leader endpoint subsets when the pod's PostgreSQL is promoted.
+-  **ports**: (optional) if the Service object has the name for the port, the same name must appear in the Endpoint object, otherwise service won't work. For example, if your service is defined as ``{Kind: Service, spec: {ports: [{name: postgresql, port: 5432, targetPort: 5432}]}}``, then you have to set ``kubernetes.ports: [{"name": "postgresql", "port": 5432}]`` and Patroni will use it for updating subsets of the leader Endpoint. This parameter is used only if `kubernetes.use_endpoints` is set.
+-  **cacert**: (optional) Specifies the file with the CA_BUNDLE file with certificates of trusted CAs to use while verifying Kubernetes API SSL certs. If not provided, patroni will use the value provided by the ServiceAccount secret.
+-  **retriable\_http\_codes**: (optional) list of HTTP status codes from K8s API to retry on. By default Patroni is retrying on ``500``, ``503``, and ``504``, or if K8s API response has ``retry-after`` HTTP header.
+
+
+.. _raft_settings:
+
+Raft (deprecated)
+-----------------
+-  **self\_addr**: ``ip:port`` to listen on for Raft connections. The ``self_addr`` must be accessible from other nodes of the cluster. If not set, the node will not participate in consensus.
+-  **bind\_addr**: (optional) ``ip:port`` to listen on for Raft connections. If not specified the ``self_addr`` will be used.
+-  **partner\_addrs**: list of other Patroni nodes in the cluster in format: ['ip1:port', 'ip2:port', 'etc...']
+-  **data\_dir**: directory where to store Raft log and snapshot. If not specified the current working directory is used.
+-  **password**: (optional) Encrypt Raft traffic with a specified password, requires ``cryptography`` python module.
+
+   Short FAQ about Raft implementation
+
+   - Q: How to list all the nodes providing consensus?
+
+     A: ``syncobj_admin -conn host:port -status`` where the host:port is the address of one of the cluster nodes
+
+   - Q: Node that was a part of consensus and has gone and I can't reuse the same IP for other node. How to remove this node from the consensus?
+
+     A: ``syncobj_admin -conn host:port -remove host2:port2`` where the ``host2:port2`` is the address of the node you want to remove from consensus.
+
+   - Q: Where to get the ``syncobj_admin`` utility?
+
+     A: It is installed together with ``pysyncobj`` module (python RAFT implementation), which is Patroni dependency.
+
+   - Q: it is possible to run Patroni node without adding in to the consensus?
+
+     A: Yes, just comment out or remove ``raft.self_addr`` from Patroni configuration.
+
+   - Q: It is possible to run Patroni and PostgreSQL only on two nodes?
+
+     A: Yes, on the third node you can run ``patroni_raft_controller`` (without Patroni and PostgreSQL). In such a setup, one can temporarily lose one node without affecting the primary.
+
+
+.. _postgresql_settings:
+
+PostgreSQL
+----------
+-  **postgresql**:
+
+   -  **authentication**:
+
+      -  **superuser**:
+
+         -  **username**: name for the superuser, set during initialization (initdb) and later used by Patroni to connect to the postgres.
+         -  **password**: password for the superuser, set during initialization (initdb).
+         -  **sslmode**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
+         -  **sslkey**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
+         -  **sslpassword**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``sslkey``.
+         -  **sslcert**: (optional) maps to the `sslcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCERT>`__ connection parameter, which specifies the location of the client certificate.
+         -  **sslrootcert**: (optional) maps to the `sslrootcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLROOTCERT>`__ connection parameter, which specifies the location of a file containing one ore more certificate authorities (CA) certificates that the client will use to verify a server's certificate.
+         -  **sslcrl**: (optional) maps to the `sslcrl <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRL>`__ connection parameter, which specifies the location of a file containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
+         -  **sslcrldir**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
+         -  **gssencmode**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
+         -  **channel_binding**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
+      -  **replication**:
+
+         -  **username**: replication username; the user will be created during initialization. Replicas will use this user to access the replication source via streaming replication
+         -  **password**: replication password; the user will be created during initialization.
+         -  **sslmode**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
+         -  **sslkey**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
+         -  **sslpassword**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``sslkey``.
+         -  **sslcert**: (optional) maps to the `sslcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCERT>`__ connection parameter, which specifies the location of the client certificate.
+         -  **sslrootcert**: (optional) maps to the `sslrootcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLROOTCERT>`__ connection parameter, which specifies the location of a file containing one ore more certificate authorities (CA) certificates that the client will use to verify a server's certificate.
+         -  **sslcrl**: (optional) maps to the `sslcrl <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRL>`__ connection parameter, which specifies the location of a file containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
+         -  **sslcrldir**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
+         -  **gssencmode**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
+         -  **channel_binding**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
+      -  **rewind**:
+
+         -  **username**: (optional) name for the user for ``pg_rewind``; the user will be created during initialization of postgres 11+ and all necessary `permissions <https://www.postgresql.org/docs/11/app-pgrewind.html#id-1.9.5.8.8>`__ will be granted.
+         -  **password**: (optional) password for the user for ``pg_rewind``; the user will be created during initialization.
+         -  **sslmode**: (optional) maps to the `sslmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLMODE>`__ connection parameter, which allows a client to specify the type of TLS negotiation mode with the server. For more information on how each mode works, please visit the `PostgreSQL documentation <https://www.postgresql.org/docs/current/libpq-ssl.html#LIBPQ-SSL-SSLMODE-STATEMENTS>`__. The default mode is ``prefer``.
+         -  **sslkey**: (optional) maps to the `sslkey <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLKEY>`__ connection parameter, which specifies the location of the secret key used with the client's certificate.
+         -  **sslpassword**: (optional) maps to the `sslpassword <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLPASSWORD>`__ connection parameter, which specifies the password for the secret key specified in ``sslkey``.
+         -  **sslcert**: (optional) maps to the `sslcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCERT>`__ connection parameter, which specifies the location of the client certificate.
+         -  **sslrootcert**: (optional) maps to the `sslrootcert <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLROOTCERT>`__ connection parameter, which specifies the location of a file containing one ore more certificate authorities (CA) certificates that the client will use to verify a server's certificate.
+         -  **sslcrl**: (optional) maps to the `sslcrl <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRL>`__ connection parameter, which specifies the location of a file containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
+         -  **sslcrldir**: (optional) maps to the `sslcrldir <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-SSLCRLDIR>`__ connection parameter, which specifies the location of a directory with files containing a certificate revocation list. A client will reject connecting to any server that has a certificate present in this list.
+         -  **gssencmode**: (optional) maps to the `gssencmode <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-GSSENCMODE>`__ connection parameter, which determines whether or with what priority a secure GSS TCP/IP connection will be negotiated with the server
+         -  **channel_binding**: (optional) maps to the `channel_binding <https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-CHANNEL-BINDING>`__ connection parameter, which controls the client's use of channel binding.
+
+   -  **callbacks**: callback scripts to run on certain actions. Patroni will pass the action, role and cluster name. (See scripts/aws.py as an example of how to write them.)
+
+      -  **on\_reload**: run this script when configuration reload is triggered.
+      -  **on\_restart**: run this script when the postgres restarts (without changing role).
+      -  **on\_role\_change**: run this script when the postgres is being promoted or demoted.
+      -  **on\_start**: run this script when the postgres starts.
+      -  **on\_stop**: run this script when the postgres stops.
+   -  **connect\_address**: IP address + port through which Postgres is accessible from other nodes and applications.
+   -  **proxy\_address**: IP address + port through which a connection pool (e.g. pgbouncer) running next to Postgres is accessible. The value is written to the member key in DCS as ``proxy_url`` and could be used/useful for service discovery.
+   -  **create\_replica\_methods**: an ordered list of the create methods for turning a Patroni node into a new replica.
+      "basebackup" is the default method; other methods are assumed to refer to scripts, each of which is configured as its
+      own config item. See :ref:`custom replica creation methods documentation <custom_replica_creation>` for further explanation.
+   -  **data\_dir**: The location of the Postgres data directory, either :ref:`existing <existing_data>` or to be initialized by Patroni.
+   -  **config\_dir**: The location of the Postgres configuration directory, defaults to the data directory. Must be writable by Patroni.
+   -  **bin\_dir**: (optional) Path to PostgreSQL binaries (pg_ctl, initdb, pg_controldata, pg_basebackup, postgres, pg_isready, pg_rewind). If not provided or is an empty string, PATH environment variable will be used to find the executables.
+   -  **bin\_name**: (optional) Make it possible to override Postgres binary names, if you are using a custom Postgres distribution:
+
+      - **pg\_ctl**: (optional) Custom name for ``pg_ctl`` binary.
+      - **initdb**: (optional) Custom name for ``initdb`` binary.
+      - **pg\controldata**: (optional) Custom name for ``pg_controldata`` binary.
+      - **pg\_basebackup**: (optional) Custom name for ``pg_basebackup`` binary.
+      - **postgres**: (optional) Custom name for ``postgres`` binary.
+      - **pg\_isready**: (optional) Custom name for ``pg_isready`` binary.
+      - **pg\_rewind**: (optional) Custom name for ``pg_rewind`` binary.
+   -  **listen**: IP address + port that Postgres listens to; must be accessible from other nodes in the cluster, if you're using streaming replication. Multiple comma-separated addresses are permitted, as long as the port component is appended after to the last one with a colon, i.e. ``listen: 127.0.0.1,127.0.0.2:5432``. Patroni will use the first address from this list to establish local connections to the PostgreSQL node.
+   -  **use\_unix\_socket**: specifies that Patroni should prefer to use unix sockets to connect to the cluster. Default value is ``false``. If ``unix_socket_directories`` is defined, Patroni will use the first suitable value from it to connect to the cluster and fallback to tcp if nothing is suitable. If ``unix_socket_directories`` is not specified in ``postgresql.parameters``, Patroni will assume that the default value should be used and omit ``host`` from the connection parameters.
+   -  **use\_unix\_socket\_repl**: specifies that Patroni should prefer to use unix sockets for replication user cluster connection. Default value is ``false``. If ``unix_socket_directories`` is defined, Patroni will use the first suitable value from it to connect to the cluster and fallback to tcp if nothing is suitable. If ``unix_socket_directories`` is not specified in ``postgresql.parameters``, Patroni will assume that the default value should be used and omit ``host`` from the connection parameters.
+   -  **pgpass**: path to the `.pgpass <https://www.postgresql.org/docs/current/static/libpq-pgpass.html>`__ password file. Patroni creates this file before executing pg\_basebackup, the post_init script and under some other circumstances. The location must be writable by Patroni.
+   -  **recovery\_conf**: additional configuration settings written to recovery.conf when configuring follower.
+   -  **custom\_conf** : path to an optional custom ``postgresql.conf`` file, that will be used in place of ``postgresql.base.conf``. The file must exist on all cluster nodes, be readable by PostgreSQL and will be included from its location on the real ``postgresql.conf``. Note that Patroni will not monitor this file for changes, nor backup it. However, its settings can still be overridden by Patroni's own configuration facilities - see :ref:`dynamic configuration <patroni_configuration>` for details.
+   -  **parameters**: list of configuration settings for Postgres. Many of these are required for replication to work.
+   -  **pg\_hba**: list of lines that Patroni will use to generate ``pg_hba.conf``. Patroni ignores this parameter if ``hba_file`` PostgreSQL parameter is set to a non-default value. Together with :ref:`dynamic configuration <dynamic_configuration>` this parameter simplifies management of ``pg_hba.conf``.
+
+      -  **- host all all 0.0.0.0/0 md5**
+      -  **- host replication replicator 127.0.0.1/32 md5**: A line like this is required for replication.
+   -  **pg\_ident**: list of lines that Patroni will use to generate ``pg_ident.conf``. Patroni ignores this parameter if ``ident_file`` PostgreSQL parameter is set to a non-default value. Together with :ref:`dynamic configuration <dynamic_configuration>` this parameter simplifies management of ``pg_ident.conf``.
+
+      -  **- mapname1 systemname1 pguser1**
+      -  **- mapname1 systemname2 pguser2**
+   -  **pg\_ctl\_timeout**: How long should pg_ctl wait when doing ``start``, ``stop`` or ``restart``. Default value is 60 seconds.
+   -  **use\_pg\_rewind**: try to use pg\_rewind on the former leader when it joins cluster as a replica.
+   -  **remove\_data\_directory\_on\_rewind\_failure**: If this option is enabled, Patroni will remove the PostgreSQL data directory and recreate the replica. Otherwise it will try to follow the new leader. Default value is **false**.
+   -  **remove\_data\_directory\_on\_diverged\_timelines**: Patroni will remove the PostgreSQL data directory and recreate the replica if it notices that timelines are diverging and the former primary can not start streaming from the new primary. This option is useful when ``pg_rewind`` can not be used. While performing timelines divergence check on PostgreSQL v10 and older Patroni will try to connect with replication credential to the "postgres" database. Hence, such access should be allowed in the pg_hba.conf. Default value is **false**.
+   -  **replica\_method**: for each create_replica_methods other than basebackup, you would add a configuration section of the same name. At a minimum, this should include "command" with a full path to the actual script to be executed. Other configuration parameters will be passed along to the script in the form "parameter=value".
+   -  **pre\_promote**: a fencing script that executes during a failover after acquiring the leader lock but before promoting the replica. If the script exits with a non-zero code, Patroni does not promote the replica and removes the leader key from DCS.
+   -  **before\_stop**: a script that executes immediately prior to stopping postgres. As opposed to a callback, this script runs synchronously, blocking shutdown until it has completed. The return code of this script does not impact whether shutdown proceeds afterwards.
+
+.. _restapi_settings:
+
+REST API
+--------
+-  **restapi**:
+
+   -  **connect\_address**: IP address (or hostname) and port, to access the Patroni's :ref:`REST API <rest_api>`. All the members of the cluster must be able to connect to this address, so unless the Patroni setup is intended for a demo inside the localhost, this address must be a non "localhost" or loopback address (ie: "localhost" or "127.0.0.1"). It can serve as an endpoint for HTTP health checks (read below about the "listen" REST API parameter), and also for user queries (either directly or via the REST API), as well as for the health checks done by the cluster members during leader elections (for example, to determine whether the leader is still running, or if there is a node which has a WAL position that is ahead of the one doing the query; etc.) The connect_address is put in the member key in DCS, making it possible to translate the member name into the address to connect to its REST API.
+   -  **listen**: IP address (or hostname) and port that Patroni will listen to for the REST API - to provide also the same health checks and cluster messaging between the participating nodes, as described above. to provide health-check information for HAProxy (or any other load balancer capable of doing a HTTP "OPTION" or "GET" checks).
+   -  **authentication**: (optional)
+
+      -  **username**: Basic-auth username to protect unsafe REST API endpoints.
+      -  **password**: Basic-auth password to protect unsafe REST API endpoints.
+   -  **certfile**: (optional): Specifies the file with the certificate in the PEM format. If the certfile is not specified or is left empty, the API server will work without SSL.
+   -  **keyfile**: (optional): Specifies the file with the secret key in the PEM format.
+   -  **keyfile\_password**: (optional): Specifies a password for decrypting the keyfile.
+   -  **cafile**: (optional): Specifies the file with the CA_BUNDLE with certificates of trusted CAs to use while verifying client certs.
+   -  **ciphers**: (optional): Specifies the permitted cipher suites (e.g. "ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-GCM-SHA256:!SSLv1:!SSLv2:!SSLv3:!TLSv1:!TLSv1.1")
+   -  **verify\_client**: (optional): ``none`` (default), ``optional`` or ``required``. When ``none`` REST API will not check client certificates. When ``required`` client certificates are required for all REST API calls. When ``optional`` client certificates are required for all unsafe REST API endpoints. When ``required`` is used, then client authentication succeeds, if the certificate signature verification succeeds.  For ``optional`` the client cert will only be checked for ``PUT``, ``POST``, ``PATCH``, and ``DELETE`` requests.
+   -  **allowlist**: (optional): Specifies the set of hosts that are allowed to call unsafe REST API endpoints. The single element could be a host name, an IP address or a network address using CIDR notation. By default ``allow all`` is used. In case if ``allowlist`` or ``allowlist_include_members`` are set, anything that is not included is rejected.
+   -  **allowlist\_include\_members**: (optional): If set to ``true`` it allows accessing unsafe REST API endpoints from other cluster members registered in DCS (IP address or hostname is taken from the members ``api_url``). Be careful, it might happen that OS will use a different IP for outgoing connections.
+   -  **http\_extra\_headers**: (optional): HTTP headers let the REST API server pass additional information with an HTTP response.
+   -  **https\_extra\_headers**: (optional): HTTPS headers let the REST API server pass additional information with an HTTP response when TLS is enabled. This will also pass additional information set in ``http_extra_headers``.
+   -  **request_queue_size**: (optional): Sets request queue size for TCP socket used by Patroni REST API.  Once the queue is full, further requests get a "Connection denied" error. The default value is 5.
+
+Here is an example of both **http_extra_headers** and **https_extra_headers**:
+
+.. code:: YAML
+
+        restapi:
+          listen: <listen>
+          connect_address: <connect_address>
+          authentication:
+            username: <username>
+            password: <password>
+          http_extra_headers:
+            'X-Frame-Options': 'SAMEORIGIN'
+            'X-XSS-Protection': '1; mode=block'
+            'X-Content-Type-Options': 'nosniff'
+          cafile: <ca file>
+          certfile: <cert>
+          keyfile: <key>
+          https_extra_headers:
+            'Strict-Transport-Security': 'max-age=31536000; includeSubDomains'
+
+.. warning::
+
+    - The ``restapi.connect_address`` must be accessible from all nodes of a given Patroni cluster. Internally Patroni is using it during the leader race to find nodes with minimal replication lag.
+    - If you enabled client certificates validation (``restapi.verify_client`` is set to ``required``), you also **must** provide **valid client certificates** in the ``ctl.certfile``, ``ctl.keyfile``, ``ctl.keyfile_password``. If not provided, Patroni will not work correctly.
+
+
+.. _patronictl_settings:
+
+CTL
+---
+-  **ctl**: (optional)
+
+   -  **authentication**:
+
+      -  **username**: Basic-auth username for accessing protected REST API endpoints. If not provided :ref:`patronictl` will use the value provided for REST API "username" parameter.
+      -  **password**: Basic-auth password for accessing protected REST API endpoints. If not provided :ref:`patronictl` will use the value provided for REST API "password" parameter.
+   -  **insecure**: Allow connections to REST API without verifying SSL certs.
+   -  **cacert**: Specifies the file with the CA_BUNDLE file or directory with certificates of trusted CAs to use while verifying REST API SSL certs. If not provided :ref:`patronictl` will use the value provided for REST API "cafile" parameter.
+   -  **certfile**: Specifies the file with the client certificate in the PEM format.
+   -  **keyfile**: Specifies the file with the client secret key in the PEM format.
+   -  **keyfile\_password**: Specifies a password for decrypting the client keyfile.
+
+Watchdog
+--------
+-  **mode**: ``off``, ``automatic`` or ``required``. When ``off`` watchdog is disabled. When ``automatic`` watchdog will be used if available, but ignored if it is not. When ``required`` the node will not become a leader unless watchdog can be successfully enabled.
+-  **device**: Path to watchdog device. Defaults to ``/dev/watchdog``.
+-  **safety_margin**: Number of seconds of safety margin between watchdog triggering and leader key expiration.
+
+.. _tags_settings:
+
+Tags
+----
+-  **clonefrom**: ``true`` or ``false``. If set to ``true`` other nodes might prefer to use this node for bootstrap (take ``pg_basebackup`` from). If there are several nodes with ``clonefrom`` tag set to ``true`` the node to bootstrap from will be chosen randomly. The default value is ``false``.
+-  **noloadbalance**: ``true`` or ``false``. If set to ``true`` the node will return HTTP Status Code 503 for the ``GET /replica`` REST API health-check and therefore will be excluded from the load-balancing. Defaults to ``false``.
+-  **replicatefrom**: The IP address/hostname of another replica. Used to support cascading replication.
+-  **nosync**: ``true`` or ``false``. If set to ``true`` the node will never be selected as a synchronous replica.
+-  **nofailover**: ``true`` or ``false``, controls whether this node is allowed to participate in the leader race and become a leader. Defaults to ``false``, meaning this node _can_ participate in leader races. 
+-  **failover_priority**: integer, controls the priority that this node should have during failover. Nodes with higher priority will be preferred over lower priority nodes if they received/replayed the same amount of WAL. However, nodes with higher values of receive/replay LSN are preferred regardless of their priority. If the ``failover_priority`` is 0 or negative - such node is not allowed to participate in the leader race and to become a leader (similar to ``nofailover: true``).
+
+.. warning::
+   Provide only one of ``nofailover`` or ``failover_priority``. Providing ``nofailover: true`` is the same as ``failover_priority: 0``, and providing ``nofailover: false`` will give the node priority 1. 
+
+In addition to these predefined tags, you can also add your own ones:
+
+-  **key1**: ``true``
+-  **key2**: ``false``
+-  **key3**: ``1.4``
+-  **key4**: ``"RandomString"``
+
+Tags are visible in the :ref:`REST API <rest_api>` and :ref:`patronictl_list` You can also check for an instance health using these tags. If the tag isn't defined for an instance, or if the respective value doesn't match the querying value, it will return HTTP Status Code 503.

extras/confd/conf.d/haproxy.toml

@@ -9,5 +9,5 @@ check_cmd = "/usr/sbin/haproxy -c -f {{ .src }}"
 reload_cmd = "haproxy -f /etc/haproxy/haproxy.cfg -p /var/run/haproxy.pid -D -sf $(cat /var/run/haproxy.pid)"
 
 keys = [
-    "/members/",
+    "/",
 ]

extras/confd/templates/haproxy-citus.tmpl

@@ -0,0 +1,32 @@
+global
+	maxconn 100
+
+defaults
+	log	global
+	mode	tcp
+	retries 2
+	timeout client 30m
+	timeout connect 4s
+	timeout server 30m
+	timeout check 5s
+
+listen stats
+	mode http
+	bind *:7000
+	stats enable
+	stats uri /
+
+listen coordinator
+	bind *:5000
+	option httpchk HEAD /primary
+	http-check expect status 200
+	default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions
+{{range gets "/0/members/*"}}	server {{base .Key}} {{$data := json .Value}}{{base (replace (index (split $data.conn_url "/") 2) "@" "/" -1)}} maxconn 100 check check-ssl port {{index (split (index (split $data.api_url "/") 2) ":") 1}} verify required ca-file /etc/ssl/certs/ssl-cert-snakeoil.pem crt /etc/ssl/private/ssl-cert-snakeoil.crt
+{{end}}
+listen workers
+	bind *:5001
+	option httpchk HEAD /primary
+	http-check expect status 200
+	default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions
+{{range gets "/*/members/*"}}{{$group := index (split .Key "/") 1}}{{if ne $group "0"}}	server {{base .Key}} {{$data := json .Value}}{{base (replace (index (split $data.conn_url "/") 2) "@" "/" -1)}} maxconn 100 check check-ssl port {{index (split (index (split $data.api_url "/") 2) ":") 1}} verify required ca-file /etc/ssl/certs/ssl-cert-snakeoil.pem crt /etc/ssl/private/ssl-cert-snakeoil.crt
+{{end}}{{end}}

extras/confd/templates/haproxy.tmpl

@@ -16,9 +16,9 @@ listen stats
 	stats enable
 	stats uri /
 
-listen master
+listen primary
 	bind *:5000
-	option httpchk HEAD /master
+	option httpchk HEAD /primary
 	http-check expect status 200
 	default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions
 {{range gets "/members/*"}}	server {{base .Key}} {{$data := json .Value}}{{base (replace (index (split $data.conn_url "/") 2) "@" "/" -1)}} maxconn 100 check port {{index (split (index (split $data.api_url "/") 2) ":") 1}}

extras/startup-scripts/README.md

@@ -1,6 +1,6 @@
 # startup scripts for Patroni
 
-This directory contains sample startup scripts for various OSes 
+This directory contains sample startup scripts for various OSes
 and management tools for Patroni.
 
 Scripts supplied:
@@ -10,7 +10,7 @@ Scripts supplied:
 Upstart job for Ubuntu 12.04 or 14.04.  Requires Upstart > 1.4. Intended for systems where Patroni has been installed on a base system, rather than in Docker.
 
 ### patroni.service
-Systemd service file, to be copied to /etc/systemd/system/patroni.service, tested on Centos 7.1 with Patroni installed from pip. 
+Systemd service file, to be copied to /etc/systemd/system/patroni.service, tested on Centos 7.1 with Patroni installed from pip.
 
 ### patroni
 Init.d service file for Debian-like distributions. Copy it to /etc/init.d/, make executable:

features/Dockerfile

@@ -0,0 +1,97 @@
+# syntax = docker/dockerfile:1.5
+# Used only for running tests using tox, see ../tox.ini
+ARG PG_MAJOR
+ARG PGHOME=/home/postgres
+ARG LC_ALL=C.UTF-8
+ARG LANG=C.UTF-8
+ARG BASE_IMAGE=postgres
+
+FROM ${BASE_IMAGE}:${PG_MAJOR}
+
+ARG PGHOME
+ARG LC_ALL
+ARG LANG
+
+ENV PGHOME="$PGHOME"
+ENV PG_USER="${PG_USER:-postgres}"
+ENV PG_GROUP="${PG_GROUP:-$PG_USER}"
+ENV LC_ALL="$LC_ALL"
+ENV LANG="$LANG"
+
+ARG ETCDVERSION=3.3.13
+ENV ETCDVERSION="$ETCDVERSION"
+ARG ETCDURL="https://github.com/coreos/etcd/releases/download/v$ETCDVERSION"
+
+USER root
+RUN set -ex \
+    && apt-get update \
+    && apt-get reinstall init-system-helpers \
+    && apt-get install -y \
+      python3-dev \
+      python3-venv \
+      rsync \
+      curl \
+      gcc \
+      golang \
+      jq  \
+      locales  \
+      sudo \
+      busybox \
+      net-tools \
+      iputils-ping \
+    && rm -rf /var/cache/apt \
+    \
+    && python3 -m venv /tox \
+    && /tox/bin/pip install --no-cache-dir tox>=4 \
+    \
+    && mkdir -p "$PGHOME" \
+    && sed -i "s|/var/lib/postgresql.*|$PGHOME:/bin/bash|" /etc/passwd \
+    && chown -R "$PG_USER:$PG_GROUP" /var/log /home/postgres \
+    \
+    # Download etcd \
+    && curl -sL "$ETCDURL/etcd-v$ETCDVERSION-linux-$(dpkg --print-architecture).tar.gz" \
+       | tar xz -C /usr/local/bin --strip=1 --wildcards --no-anchored etcd etcdctl
+
+ENV PATH="/tox/bin:$PATH"
+
+# This Dockerfile syntax only works with docker buildx and the syntax
+# line at the top of this file.
+COPY <<EOF /tox-wrapper.sh
+#!/usr/bin/env bash
+set -ex
+copy_output() {
+    if [[ -d "\$PGHOME/src/features/output" && /src/features ]] ;then
+        cp -a "\$PGHOME/src/features/output" "/src/features/output-\$HOSTNAME"
+        find "/src/features/output-\$HOSTNAME" -type f -exec chmod 666 {} \\;
+        find "/src/features/output-\$HOSTNAME" -type d -exec chmod 777 {} \\;
+    fi
+}
+
+# Ensure the copy is ran if the container is stopped with `docker stop` or `docker kill`
+trap 'copy_output' SIGTERM
+# For architectures such as aarch we need to get the respective GOARCH
+# so we can tell etcd we're ok with running an unsupported architecture.
+export ETCD_UNSUPPORTED_ARCH=$(go env GOARCH)
+cd /src
+runuser -u "\$PG_USER" -- \\
+    find . ! -readable 2>/dev/null \\
+    | sed 's|^./||' >/tmp/copy_exclude.lst \\
+    || true
+runuser -u "\$PG_USER" -- \\
+    rsync -a \\
+    --exclude=.tox \\
+    --exclude="features/output*" \\
+    --exclude-from="/tmp/copy_exclude.lst" \\
+    . "\$PGHOME/src/"
+cd "\$PGHOME/src"
+runuser -u "\$PG_USER" -w ETCD_UNSUPPORTED_ARCH -- "\$@" &
+wait $!
+# SIGINT whilst child proc is running is not seen by trap so we run a copy here instead of using
+# trap copy_output SIGINT EXIT
+copy_output
+EOF
+RUN chmod +x /tox-wrapper.sh
+
+VOLUME /src
+
+ENTRYPOINT ["/tox-wrapper.sh"]

features/backup_restore.py

@@ -6,6 +6,7 @@ if __name__ == "__main__":
     parser = argparse.ArgumentParser()
     parser.add_argument("--datadir", required=True)
     parser.add_argument("--sourcedir", required=True)
+    parser.add_argument("--test-argument", required=True)
     args, _ = parser.parse_known_args()
 
     shutil.copytree(args.sourcedir, args.datadir)

features/basic_replication.feature

@@ -21,12 +21,9 @@ Feature: basic replication
     And I shut down postgres1
     Then "sync" key in DCS has sync_standby=postgres2 after 10 seconds
     When I start postgres1
-    And "members/postgres1" key in DCS has state=running after 10 seconds
-    And I sleep for 2 seconds
-    When I issue a GET request to http://127.0.0.1:8010/sync
-    Then I receive a response code 200
-    When I issue a GET request to http://127.0.0.1:8009/async
-    Then I receive a response code 200
+    Then "members/postgres1" key in DCS has state=running after 10 seconds
+    And Status code on GET http://127.0.0.1:8010/sync is 200 after 3 seconds
+    And Status code on GET http://127.0.0.1:8009/async is 200 after 3 seconds
 
   Scenario: check stuck sync replica
     Given I issue a PATCH request to http://127.0.0.1:8008/config with {"pause": true, "maximum_lag_on_syncnode": 15000000, "postgresql": {"parameters": {"synchronous_commit": "remote_apply"}}}
@@ -38,11 +35,8 @@ Feature: basic replication
     And I load data on postgres0
     Then "sync" key in DCS has sync_standby=postgres1 after 15 seconds
     And I resume wal replay on postgres2
-    And I sleep for 2 seconds
-    And I issue a GET request to http://127.0.0.1:8009/sync
-    Then I receive a response code 200
-    When I issue a GET request to http://127.0.0.1:8010/async
-    Then I receive a response code 200
+    And Status code on GET http://127.0.0.1:8009/sync is 200 after 3 seconds
+    And Status code on GET http://127.0.0.1:8010/async is 200 after 3 seconds
     When I issue a PATCH request to http://127.0.0.1:8008/config with {"pause": null, "maximum_lag_on_syncnode": -1, "postgresql": {"parameters": {"synchronous_commit": "on"}}}
     Then I receive a response code 200
     And I drop table on postgres0
@@ -50,23 +44,17 @@ Feature: basic replication
   Scenario: check multi sync replication
     Given I issue a PATCH request to http://127.0.0.1:8008/config with {"synchronous_node_count": 2}
     Then I receive a response code 200
-    And I sleep for 10 seconds
-    Then "sync" key in DCS has sync_standby=postgres1,postgres2 after 5 seconds
-    When I issue a GET request to http://127.0.0.1:8010/sync
-    Then I receive a response code 200
-    When I issue a GET request to http://127.0.0.1:8009/sync
-    Then I receive a response code 200
+    Then "sync" key in DCS has sync_standby=postgres1,postgres2 after 10 seconds
+    And Status code on GET http://127.0.0.1:8010/sync is 200 after 3 seconds
+    And Status code on GET http://127.0.0.1:8009/sync is 200 after 3 seconds
     When I issue a PATCH request to http://127.0.0.1:8008/config with {"synchronous_node_count": 1}
     Then I receive a response code 200
     And I shut down postgres1
-    And I sleep for 10 seconds
     Then "sync" key in DCS has sync_standby=postgres2 after 10 seconds
     When I start postgres1
-    And "members/postgres1" key in DCS has state=running after 10 seconds
-    When I issue a GET request to http://127.0.0.1:8010/sync
-    Then I receive a response code 200
-    When I issue a GET request to http://127.0.0.1:8009/async
-    Then I receive a response code 200
+    Then "members/postgres1" key in DCS has state=running after 10 seconds
+    And Status code on GET http://127.0.0.1:8010/sync is 200 after 3 seconds
+    And Status code on GET http://127.0.0.1:8009/async is 200 after 3 seconds
 
   Scenario: check the basic failover in synchronous mode
     Given I run patronictl.py pause batman
@@ -77,20 +65,21 @@ Feature: basic replication
     Then I receive a response returncode 0
     And postgres2 role is the primary after 24 seconds
     And Response on GET http://127.0.0.1:8010/history contains recovery after 10 seconds
+    And there is a postgres2_cb.log with "on_role_change master batman" in postgres2 data directory
     When I issue a PATCH request to http://127.0.0.1:8010/config with {"synchronous_mode": null, "master_start_timeout": 0}
     Then I receive a response code 200
     When I add the table bar to postgres2
     Then table bar is present on postgres1 after 20 seconds
     And Response on GET http://127.0.0.1:8010/config contains master_start_timeout after 10 seconds
 
-  Scenario: check immediate failover when master_start_timeout=0
-    Given I kill postmaster on postgres2
-    Then postgres1 is a leader after 10 seconds
-    And postgres1 role is the primary after 10 seconds
-
-  Scenario: check rejoin of the former master with pg_rewind
+  Scenario: check rejoin of the former primary with pg_rewind
     Given I add the table splitbrain to postgres0
     And I start postgres0
     Then postgres0 role is the secondary after 20 seconds
-    When I add the table buz to postgres1
+    When I add the table buz to postgres2
     Then table buz is present on postgres0 after 20 seconds
+
+  @reject-duplicate-name
+  Scenario: check graceful rejection when two nodes have the same name
+    Given I start duplicate postgres0 on port 8011
+    Then there is one of ["Can't start; there is already a node named 'postgres0' running"] CRITICAL in the dup-postgres0 patroni log after 5 seconds

features/citus.feature

@@ -0,0 +1,73 @@
+Feature: citus
+  We should check that coordinator discovers and registers workers and clients don't have errors when worker cluster switches over
+
+  Scenario: check that worker cluster is registered in the coordinator
+    Given I start postgres0 in citus group 0
+    And I start postgres2 in citus group 1
+    Then postgres0 is a leader in a group 0 after 10 seconds
+    And postgres2 is a leader in a group 1 after 10 seconds
+    When I start postgres1 in citus group 0
+    And I start postgres3 in citus group 1
+    Then replication works from postgres0 to postgres1 after 15 seconds
+    Then replication works from postgres2 to postgres3 after 15 seconds
+    And postgres0 is registered in the postgres0 as the primary in group 0 after 5 seconds
+    And postgres2 is registered in the postgres0 as the primary in group 1 after 5 seconds
+
+  Scenario: coordinator failover updates pg_dist_node
+    Given I run patronictl.py failover batman --group 0 --candidate postgres1 --force
+    Then postgres1 role is the primary after 10 seconds
+    And "members/postgres0" key in a group 0 in DCS has state=running after 15 seconds
+    And replication works from postgres1 to postgres0 after 15 seconds
+    And postgres1 is registered in the postgres2 as the primary in group 0 after 5 seconds
+    And "sync" key in a group 0 in DCS has sync_standby=postgres0 after 15 seconds
+    When I run patronictl.py switchover batman --group 0 --candidate postgres0 --force
+    Then postgres0 role is the primary after 10 seconds
+    And replication works from postgres0 to postgres1 after 15 seconds
+    And postgres0 is registered in the postgres2 as the primary in group 0 after 5 seconds
+    And "sync" key in a group 0 in DCS has sync_standby=postgres1 after 15 seconds
+
+  Scenario: worker switchover doesn't break client queries on the coordinator
+    Given I create a distributed table on postgres0
+    And I start a thread inserting data on postgres0
+    When I run patronictl.py switchover batman --group 1 --force
+    Then I receive a response returncode 0
+    And postgres3 role is the primary after 10 seconds
+    And "members/postgres2" key in a group 1 in DCS has state=running after 15 seconds
+    And replication works from postgres3 to postgres2 after 15 seconds
+    And postgres3 is registered in the postgres0 as the primary in group 1 after 5 seconds
+    And "sync" key in a group 1 in DCS has sync_standby=postgres2 after 15 seconds
+    And a thread is still alive
+    When I run patronictl.py switchover batman --group 1 --force
+    Then I receive a response returncode 0
+    And postgres2 role is the primary after 10 seconds
+    And replication works from postgres2 to postgres3 after 15 seconds
+    And postgres2 is registered in the postgres0 as the primary in group 1 after 5 seconds
+    And "sync" key in a group 1 in DCS has sync_standby=postgres3 after 15 seconds
+    And a thread is still alive
+    When I stop a thread
+    Then a distributed table on postgres0 has expected rows
+
+  Scenario: worker primary restart doesn't break client queries on the coordinator
+    Given I cleanup a distributed table on postgres0
+    And I start a thread inserting data on postgres0
+    When I run patronictl.py restart batman postgres2 --group 1 --force
+    Then I receive a response returncode 0
+    And postgres2 role is the primary after 10 seconds
+    And replication works from postgres2 to postgres3 after 15 seconds
+    And postgres2 is registered in the postgres0 as the primary in group 1 after 5 seconds
+    And a thread is still alive
+    When I stop a thread
+    Then a distributed table on postgres0 has expected rows
+
+  Scenario: check that in-flight transaction is rolled back after timeout when other workers need to change pg_dist_node
+    Given I start postgres4 in citus group 2
+    Then postgres4 is a leader in a group 2 after 10 seconds
+    And "members/postgres4" key in a group 2 in DCS has role=master after 3 seconds
+    When I run patronictl.py edit-config batman --group 2 -s ttl=20 --force
+    Then I receive a response returncode 0
+    And I receive a response output "+ttl: 20"
+    Then postgres4 is registered in the postgres2 as the primary in group 2 after 5 seconds
+    When I shut down postgres4
+    Then there is a transaction in progress on postgres0 changing pg_dist_node after 5 seconds
+    When I run patronictl.py restart batman postgres2 --group 1 --force
+    Then a transaction finishes in 20 seconds

features/dcs_failsafe_mode.feature

@@ -0,0 +1,116 @@
+Feature: dcs failsafe mode
+  We should check the basic dcs failsafe mode functioning
+
+  Scenario: check failsafe mode can be successfully enabled
+    Given I start postgres0
+    And postgres0 is a leader after 10 seconds
+    Then "config" key in DCS has ttl=30 after 10 seconds
+    When I issue a PATCH request to http://127.0.0.1:8008/config with {"loop_wait": 2, "ttl": 20, "retry_timeout": 3, "failsafe_mode": true}
+    Then I receive a response code 200
+    And Response on GET http://127.0.0.1:8008/failsafe contains postgres0 after 10 seconds
+    When I issue a GET request to http://127.0.0.1:8008/failsafe
+    Then I receive a response code 200
+    And I receive a response postgres0 http://127.0.0.1:8008/patroni
+    When I issue a PATCH request to http://127.0.0.1:8008/config with {"postgresql": {"parameters": {"wal_level": "logical"}},"slots":{"dcs_slot_1": null,"postgres0":null}}
+    Then I receive a response code 200
+    When I issue a PATCH request to http://127.0.0.1:8008/config with {"slots": {"dcs_slot_0": {"type": "logical", "database": "postgres", "plugin": "test_decoding"}}}
+    Then I receive a response code 200
+
+  @dcs-failsafe
+  Scenario: check one-node cluster is functioning while DCS is down
+    Given DCS is down
+    Then Response on GET http://127.0.0.1:8008/primary contains failsafe_mode_is_active after 12 seconds
+    And postgres0 role is the primary after 10 seconds
+
+  @dcs-failsafe
+  Scenario: check new replica isn't promoted when leader is down and DCS is up
+    Given DCS is up
+    When I do a backup of postgres0
+    And I shut down postgres0
+    When I start postgres1 in a cluster batman from backup with no_leader
+    Then postgres1 role is the replica after 12 seconds
+
+  Scenario: check leader and replica are both in /failsafe key after leader is back
+    Given I start postgres0
+    And I start postgres1
+    Then "members/postgres0" key in DCS has state=running after 10 seconds
+    And "members/postgres1" key in DCS has state=running after 2 seconds
+    And Response on GET http://127.0.0.1:8009/failsafe contains postgres1 after 10 seconds
+    When I issue a GET request to http://127.0.0.1:8009/failsafe
+    Then I receive a response code 200
+    And I receive a response postgres0 http://127.0.0.1:8008/patroni
+    And I receive a response postgres1 http://127.0.0.1:8009/patroni
+
+  @dcs-failsafe
+  @slot-advance
+  Scenario: check leader and replica are functioning while DCS is down
+    Given I get all changes from physical slot dcs_slot_1 on postgres0
+    Then physical slot dcs_slot_1 is in sync between postgres0 and postgres1 after 10 seconds
+    And logical slot dcs_slot_0 is in sync between postgres0 and postgres1 after 10 seconds
+    And DCS is down
+    Then Response on GET http://127.0.0.1:8008/primary contains failsafe_mode_is_active after 12 seconds
+    Then postgres0 role is the primary after 10 seconds
+    And postgres1 role is the replica after 2 seconds
+    And replication works from postgres0 to postgres1 after 10 seconds
+    When I get all changes from logical slot dcs_slot_0 on postgres0
+    And I get all changes from physical slot dcs_slot_1 on postgres0
+    Then logical slot dcs_slot_0 is in sync between postgres0 and postgres1 after 20 seconds
+    And physical slot dcs_slot_1 is in sync between postgres0 and postgres1 after 10 seconds
+
+  @dcs-failsafe
+  Scenario: check primary is demoted when one replica is shut down and DCS is down
+    Given DCS is down
+    And I kill postgres1
+    And I kill postmaster on postgres1
+    Then postgres0 role is the replica after 12 seconds
+
+  @dcs-failsafe
+  Scenario: check known replica is promoted when leader is down and DCS is up
+    Given I kill postgres0
+    And I shut down postmaster on postgres0
+    And DCS is up
+    When I start postgres1
+    Then "members/postgres1" key in DCS has state=running after 10 seconds
+    And postgres1 role is the primary after 25 seconds
+
+  @dcs-failsafe
+  Scenario: scale to three-node cluster
+    Given I start postgres0
+    And I start postgres2
+    Then "members/postgres2" key in DCS has state=running after 10 seconds
+    And "members/postgres0" key in DCS has state=running after 20 seconds
+    And Response on GET http://127.0.0.1:8008/failsafe contains postgres2 after 10 seconds
+    And replication works from postgres1 to postgres0 after 10 seconds
+    And replication works from postgres1 to postgres2 after 10 seconds
+
+  @dcs-failsafe
+  @slot-advance
+  Scenario: make sure permanent slots exist on replicas
+    Given I issue a PATCH request to http://127.0.0.1:8009/config with {"slots":{"dcs_slot_0":null,"dcs_slot_2":{"type":"logical","database":"postgres","plugin":"test_decoding"}}}
+    Then logical slot dcs_slot_2 is in sync between postgres1 and postgres0 after 20 seconds
+    And logical slot dcs_slot_2 is in sync between postgres1 and postgres2 after 20 seconds
+    When I get all changes from physical slot dcs_slot_1 on postgres1
+    Then physical slot dcs_slot_1 is in sync between postgres1 and postgres0 after 10 seconds
+    And physical slot dcs_slot_1 is in sync between postgres1 and postgres2 after 10 seconds
+    And physical slot postgres0 is in sync between postgres1 and postgres2 after 10 seconds
+
+  @dcs-failsafe
+  Scenario: check three-node cluster is functioning while DCS is down
+    Given DCS is down
+    Then Response on GET http://127.0.0.1:8009/primary contains failsafe_mode_is_active after 12 seconds
+    Then postgres1 role is the primary after 10 seconds
+    And postgres0 role is the replica after 2 seconds
+    And postgres2 role is the replica after 2 seconds
+
+  @dcs-failsafe
+  @slot-advance
+  Scenario: check that permanent slots are in sync between nodes while DCS is down
+    Given replication works from postgres1 to postgres0 after 10 seconds
+    And replication works from postgres1 to postgres2 after 10 seconds
+    When I get all changes from logical slot dcs_slot_2 on postgres1
+    And I get all changes from physical slot dcs_slot_1 on postgres1
+    Then logical slot dcs_slot_2 is in sync between postgres1 and postgres0 after 20 seconds
+    And logical slot dcs_slot_2 is in sync between postgres1 and postgres2 after 20 seconds
+    And physical slot dcs_slot_1 is in sync between postgres1 and postgres0 after 10 seconds
+    And physical slot dcs_slot_1 is in sync between postgres1 and postgres2 after 10 seconds
+    And physical slot postgres0 is in sync between postgres1 and postgres2 after 10 seconds

features/environment.py

@@ -1,10 +1,13 @@
 import abc
 import datetime
+import glob
 import os
 import json
+import psutil
+import re
 import shutil
 import signal
-import six
+import stat
 import subprocess
 import sys
 import tempfile
@@ -14,12 +17,11 @@ import yaml
 
 import patroni.psycopg as psycopg
 
+from http.server import BaseHTTPRequestHandler, HTTPServer
 from patroni.request import PatroniRequest
-from six.moves.BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
 
 
-@six.add_metaclass(abc.ABCMeta)
-class AbstractController(object):
+class AbstractController(abc.ABC):
 
     def __init__(self, context, name, work_directory, output_dir):
         self._context = context
@@ -50,15 +52,14 @@ class AbstractController(object):
         self._log = open(os.path.join(self._output_dir, self._name + '.log'), 'a')
         self._handle = self._start()
 
-        assert self._has_started(), "Process {0} is not running after being started".format(self._name)
-
         max_wait_limit *= self._context.timeout_multiplier
         for _ in range(max_wait_limit):
+            assert self._has_started(), "Process {0} is not running after being started".format(self._name)
             if self._is_accessible():
                 break
             time.sleep(1)
         else:
-            assert False,\
+            assert False, \
                 "{0} instance is not available for queries after {1} seconds".format(self._name, max_wait_limit)
 
     def stop(self, kill=False, timeout=15, _=False):
@@ -100,6 +101,7 @@ class PatroniController(AbstractController):
             self.watchdog = None
 
         self._scope = (custom_config or {}).get('scope', 'batman')
+        self._citus_group = (custom_config or {}).get('citus', {}).get('group')
         self._config = self._make_patroni_test_config(name, custom_config)
         self._closables = []
 
@@ -141,7 +143,7 @@ class PatroniController(AbstractController):
             self.watchdog.start()
         env = os.environ.copy()
         if isinstance(self._context.dcs_ctl, KubernetesController):
-            self._context.dcs_ctl.create_pod(self._name[8:], self._scope)
+            self._context.dcs_ctl.create_pod(self._name[8:], self._scope, self._citus_group)
             env['PATRONI_KUBERNETES_POD_IP'] = '10.0.0.' + self._name[-1]
         if os.name == 'nt':
             env['BEHAVE_DEBUG'] = 'true'
@@ -160,9 +162,10 @@ class PatroniController(AbstractController):
 
     def stop(self, kill=False, timeout=15, postgres=False):
         if postgres:
-            return subprocess.call(['pg_ctl', '-D', self._data_dir, 'stop', '-mi', '-w'])
+            mode = 'i' if kill else 'f'
+            return subprocess.call(['pg_ctl', '-D', self._data_dir, 'stop', '-m' + mode, '-w'])
         super(PatroniController, self).stop(kill, timeout)
-        if isinstance(self._context.dcs_ctl, KubernetesController):
+        if isinstance(self._context.dcs_ctl, KubernetesController) and not kill:
             self._context.dcs_ctl.delete_pod(self._name[8:])
         if self.watchdog:
             self.watchdog.stop()
@@ -177,22 +180,28 @@ class PatroniController(AbstractController):
         patroni_config_name = self.PATRONI_CONFIG.format(name)
         patroni_config_path = os.path.join(self._output_dir, patroni_config_name)
 
-        with open(patroni_config_name) as f:
+        with open('postgres0.yml') as f:
             config = yaml.safe_load(f)
             config.pop('etcd', None)
 
         raft_port = os.environ.get('RAFT_PORT')
-        if raft_port:
+        # If patroni_raft_controller is suspended two Patroni members is enough to get a quorum,
+        # therefore we don't want Patroni to join as a voting member when testing dcs_failsafe_mode.
+        if raft_port and not self._output_dir.endswith('dcs_failsafe_mode'):
             os.environ['RAFT_PORT'] = str(int(raft_port) + 1)
             config['raft'] = {'data_dir': self._output_dir, 'self_addr': 'localhost:' + os.environ['RAFT_PORT']}
 
-        host = config['postgresql']['listen'].split(':')[0]
+        host = config['restapi']['listen'].rsplit(':', 1)[0]
+        config['restapi']['listen'] = config['restapi']['connect_address'] = '{}:{}'.format(host, 8008 + int(name[-1]))
 
+        host = config['postgresql']['listen'].rsplit(':', 1)[0]
         config['postgresql']['listen'] = config['postgresql']['connect_address'] = '{0}:{1}'.format(host, self.__PORT)
 
         config['name'] = name
         config['postgresql']['data_dir'] = self._data_dir.replace('\\', '/')
         config['postgresql']['basebackup'] = [{'checkpoint': 'fast'}]
+        config['postgresql']['callbacks'] = {
+            'on_role_change': '{0} features/callback2.py {1}'.format(self._context.pctl.PYTHON, name)}
         config['postgresql']['use_unix_socket'] = os.name != 'nt'  # windows doesn't yet support unix-domain sockets
         config['postgresql']['use_unix_socket_repl'] = os.name != 'nt'
         config['postgresql']['pgpass'] = os.path.join(tempfile.gettempdir(), 'pgpass_' + name).replace('\\', '/')
@@ -200,7 +209,32 @@ class PatroniController(AbstractController):
             'logging_collector': 'on', 'log_destination': 'csvlog',
             'log_directory': self._output_dir.replace('\\', '/'),
             'log_filename': name + '.log', 'log_statement': 'all', 'log_min_messages': 'debug1',
-            'unix_socket_directories': tempfile.gettempdir().replace('\\', '/')})
+            'shared_buffers': '1MB', 'unix_socket_directories': tempfile.gettempdir().replace('\\', '/')})
+        config['postgresql']['pg_hba'] = [
+            'local all all trust',
+            'local replication all trust',
+            'host replication replicator all md5',
+            'host all all all md5'
+        ]
+
+        if self._context.postgres_supports_ssl and self._context.certfile:
+            config['postgresql']['parameters'].update({
+                'ssl': 'on',
+                'ssl_ca_file': self._context.certfile.replace('\\', '/'),
+                'ssl_cert_file': self._context.certfile.replace('\\', '/'),
+                'ssl_key_file': self._context.keyfile.replace('\\', '/')
+            })
+            for user in config['postgresql'].get('authentication').keys():
+                config['postgresql'].get('authentication', {}).get(user, {}).update({
+                    'sslmode': 'verify-ca',
+                    'sslrootcert': self._context.certfile,
+                    'sslcert': self._context.certfile,
+                    'sslkey': self._context.keyfile
+                })
+            for i, line in enumerate(list(config['postgresql']['pg_hba'])):
+                if line.endswith('md5'):
+                    # we want to verify client cert first and than password
+                    config['postgresql']['pg_hba'][i] = 'hostssl' + line[4:] + ' clientcert=verify-ca'
 
         if 'bootstrap' in config:
             config['bootstrap']['post_bootstrap'] = 'psql -w -c "SELECT 1"'
@@ -211,27 +245,47 @@ class PatroniController(AbstractController):
             self.recursive_update(config, custom_config)
 
         self.recursive_update(config, {
-            'bootstrap': {'dcs': {'loop_wait': 2, 'postgresql': {'parameters': {'wal_keep_segments': 100}}}}})
+            'log': {
+                'format': '%(asctime)s %(levelname)s [%(pathname)s:%(lineno)d - %(funcName)s]: %(message)s',
+                'loggers': {'patroni.postgresql.callback_executor': 'DEBUG'}
+            },
+            'bootstrap': {
+                'dcs': {
+                    'loop_wait': 2,
+                    'postgresql': {
+                        'parameters': {
+                            'wal_keep_segments': 100,
+                            'archive_mode': 'on',
+                            'archive_command': (PatroniPoolController.ARCHIVE_RESTORE_SCRIPT
+                                                + ' --mode archive '
+                                                + '--dirname {} --filename %f --pathname %p').format(
+                                                    os.path.join(self._work_directory, 'data', 'wal_archive'))
+                        }
+                    }
+                }
+            }
+        })
         if config['postgresql'].get('callbacks', {}).get('on_role_change'):
             config['postgresql']['callbacks']['on_role_change'] += ' ' + str(self.__PORT)
 
         with open(patroni_config_path, 'w') as f:
             yaml.safe_dump(config, f, default_flow_style=False)
 
-        user = config['postgresql'].get('authentication', config['postgresql']).get('superuser', {})
-        self._connkwargs = {k: user[n] for n, k in [('username', 'user'), ('password', 'password')] if n in user}
-        self._connkwargs.update({'host': host, 'port': self.__PORT, 'dbname': 'postgres'})
+        self._connkwargs = config['postgresql'].get('authentication', config['postgresql']).get('superuser', {})
+        self._connkwargs.update({'host': host, 'port': self.__PORT, 'dbname': 'postgres',
+                                 'user': self._connkwargs.pop('username', None)})
 
         self._replication = config['postgresql'].get('authentication', config['postgresql']).get('replication', {})
-        self._replication.update({'host': host, 'port': self.__PORT, 'dbname': 'postgres'})
+        self._replication.update({'host': host, 'port': self.__PORT, 'user': self._replication.pop('username', None)})
         self._restapi_url = 'http://{0}'.format(config['restapi']['connect_address'])
+        if self._context.certfile:
+            self._restapi_url = self._restapi_url.replace('http://', 'https://')
 
         return patroni_config_path
 
     def _connection(self):
         if not self._conn or self._conn.closed != 0:
             self._conn = psycopg.connect(**self._connkwargs)
-            self._conn.autocommit = True
         return self._conn
 
     def _cursor(self):
@@ -284,13 +338,23 @@ class PatroniController(AbstractController):
 
     @property
     def backup_source(self):
-        return 'postgres://{username}:{password}@{host}:{port}/{dbname}'.format(**self._replication)
+        def escape(value):
+            return re.sub(r'([\'\\ ])', r'\\\1', str(value))
+
+        return ' '.join('{0}={1}'.format(k, escape(v)) for k, v in self._replication.items())
 
     def backup(self, dest=os.path.join('data', 'basebackup')):
         subprocess.call(PatroniPoolController.BACKUP_SCRIPT + ['--walmethod=none',
                         '--datadir=' + os.path.join(self._work_directory, dest),
                         '--dbname=' + self.backup_source])
 
+    def read_patroni_log(self, level):
+        try:
+            with open(str(os.path.join(self._output_dir or '', self._name + ".log"))) as f:
+                return [line for line in f.readlines() if line[24:24 + len(level)] == level]
+        except IOError:
+            return []
+
 
 class ProcessHang(object):
 
@@ -323,6 +387,7 @@ class AbstractDcsController(AbstractController):
 
     def __init__(self, context, mktemp=True):
         work_directory = mktemp and tempfile.mkdtemp() or None
+        self._paused = False
         super(AbstractDcsController, self).__init__(context, self.name(), work_directory, context.pctl.output_dir)
 
     def _is_accessible(self):
@@ -334,11 +399,22 @@ class AbstractDcsController(AbstractController):
         if self._work_directory:
             shutil.rmtree(self._work_directory)
 
-    def path(self, key=None, scope='batman'):
-        return self._CLUSTER_NODE.format(scope) + (key and '/' + key or '')
+    def path(self, key=None, scope='batman', group=None):
+        citus_group = '/{0}'.format(group) if group is not None else ''
+        return self._CLUSTER_NODE.format(scope) + citus_group + (key and '/' + key or '')
+
+    def start_outage(self):
+        if not self._paused and self._handle:
+            self._handle.suspend()
+            self._paused = True
+
+    def stop_outage(self):
+        if self._paused and self._handle:
+            self._handle.resume()
+            self._paused = False
 
     @abc.abstractmethod
-    def query(self, key, scope='batman'):
+    def query(self, key, scope='batman', group=None):
         """ query for a value of a given key """
 
     @abc.abstractmethod
@@ -372,8 +448,8 @@ class ConsulController(AbstractDcsController):
         self._config_file = self._work_directory + '.json'
         with open(self._config_file, 'wb') as f:
             f.write(b'{"session_ttl_min":"5s","server":true,"bootstrap":true,"advertise_addr":"127.0.0.1"}')
-        return subprocess.Popen(['consul', 'agent', '-config-file', self._config_file, '-data-dir',
-                                 self._work_directory], stdout=self._log, stderr=subprocess.STDOUT)
+        return psutil.Popen(['consul', 'agent', '-config-file', self._config_file, '-data-dir',
+                             self._work_directory], stdout=self._log, stderr=subprocess.STDOUT)
 
     def stop(self, kill=False, timeout=15):
         super(ConsulController, self).stop(kill=kill, timeout=timeout)
@@ -386,11 +462,11 @@ class ConsulController(AbstractDcsController):
         except Exception:
             return False
 
-    def path(self, key=None, scope='batman'):
-        return super(ConsulController, self).path(key, scope)[1:]
+    def path(self, key=None, scope='batman', group=None):
+        return super(ConsulController, self).path(key, scope, group)[1:]
 
-    def query(self, key, scope='batman'):
-        _, value = self._client.kv.get(self.path(key, scope))
+    def query(self, key, scope='batman', group=None):
+        _, value = self._client.kv.get(self.path(key, scope, group))
         return value and value['Value'].decode('utf-8')
 
     def cleanup_service_tree(self):
@@ -409,8 +485,8 @@ class AbstractEtcdController(AbstractDcsController):
         self._client_cls = client_cls
 
     def _start(self):
-        return subprocess.Popen(["etcd", "--data-dir", self._work_directory],
-                                stdout=self._log, stderr=subprocess.STDOUT)
+        return psutil.Popen(["etcd", "--enable-v2=true", "--data-dir", self._work_directory],
+                            stdout=self._log, stderr=subprocess.STDOUT)
 
     def _is_running(self):
         from patroni.dcs.etcd import DnsCachingResolver
@@ -430,10 +506,10 @@ class EtcdController(AbstractEtcdController):
         super(EtcdController, self).__init__(context, EtcdClient)
         os.environ['PATRONI_ETCD_HOST'] = 'localhost:2379'
 
-    def query(self, key, scope='batman'):
+    def query(self, key, scope='batman', group=None):
         import etcd
         try:
-            return self._client.get(self.path(key, scope)).value
+            return self._client.get(self.path(key, scope, group)).value
         except etcd.EtcdKeyNotFound:
             return None
 
@@ -454,9 +530,9 @@ class Etcd3Controller(AbstractEtcdController):
         super(Etcd3Controller, self).__init__(context, Etcd3Client)
         os.environ['PATRONI_ETCD3_HOST'] = 'localhost:2379'
 
-    def query(self, key, scope='batman'):
+    def query(self, key, scope='batman', group=None):
         import base64
-        response = self._client.range(self.path(key, scope))
+        response = self._client.range(self.path(key, scope, group))
         for k in response.get('kvs', []):
             return base64.b64decode(k['value']).decode('utf-8') if 'value' in k else None
 
@@ -467,7 +543,43 @@ class Etcd3Controller(AbstractEtcdController):
             assert False, "exception when cleaning up etcd contents: {0}".format(e)
 
 
-class KubernetesController(AbstractDcsController):
+class AbstractExternalDcsController(AbstractDcsController):
+
+    def __init__(self, context, mktemp=True):
+        super(AbstractExternalDcsController, self).__init__(context, mktemp)
+        self._wrapper = ['sudo']
+
+    def _start(self):
+        return self._external_pid
+
+    def start_outage(self):
+        if not self._paused:
+            subprocess.call(self._wrapper + ['kill', '-SIGSTOP', self._external_pid])
+            self._paused = True
+
+    def stop_outage(self):
+        if self._paused:
+            subprocess.call(self._wrapper + ['kill', '-SIGCONT', self._external_pid])
+            self._paused = False
+
+    def _has_started(self):
+        return True
+
+    @abc.abstractmethod
+    def process_name():
+        """process name to search with pgrep"""
+
+    def _is_running(self):
+        if not self._handle:
+            self._external_pid = subprocess.check_output(['pgrep', '-nf', self.process_name()]).decode('utf-8').strip()
+            return False
+        return True
+
+    def stop(self):
+        pass
+
+
+class KubernetesController(AbstractExternalDcsController):
 
     def __init__(self, context):
         super(KubernetesController, self).__init__(context)
@@ -476,19 +588,48 @@ class KubernetesController(AbstractDcsController):
         self._label_selector = ','.join('{0}={1}'.format(k, v) for k, v in self._labels.items())
         os.environ['PATRONI_KUBERNETES_LABELS'] = json.dumps(self._labels)
         os.environ['PATRONI_KUBERNETES_USE_ENDPOINTS'] = 'true'
-        os.environ['PATRONI_KUBERNETES_BYPASS_API_SERVICE'] = 'true'
+        os.environ.setdefault('PATRONI_KUBERNETES_BYPASS_API_SERVICE', 'true')
 
         from patroni.dcs.kubernetes import k8s_client, k8s_config
-        k8s_config.load_kube_config(context='local')
+        k8s_config.load_kube_config(context=os.environ.setdefault('PATRONI_KUBERNETES_CONTEXT', 'kind-kind'))
         self._client = k8s_client
         self._api = self._client.CoreV1Api()
 
-    def _start(self):
-        pass
+    def process_name(self):
+        return "localkube"
 
-    def create_pod(self, name, scope):
+    def _is_running(self):
+        if not self._handle:
+            context = os.environ.get('PATRONI_KUBERNETES_CONTEXT')
+            if context.startswith('kind-'):
+                container = '{0}-control-plane'.format(context[5:])
+                api_process = 'kube-apiserver'
+            elif context.startswith('k3d-'):
+                container = '{0}-server-0'.format(context)
+                api_process = 'k3s server'
+            else:
+                return super(KubernetesController, self)._is_running()
+            try:
+                docker = 'docker'
+                with open(os.devnull, 'w') as null:
+                    if subprocess.call([docker, 'info'], stdout=null, stderr=null) != 0:
+                        raise Exception
+            except Exception:
+                docker = 'podman'
+                with open(os.devnull, 'w') as null:
+                    if subprocess.call([docker, 'info'], stdout=null, stderr=null) != 0:
+                        raise Exception
+            self._wrapper = [docker, 'exec', container]
+            self._external_pid = subprocess.check_output(self._wrapper + ['pidof', api_process]).decode('utf-8').strip()
+            return False
+        return True
+
+    def create_pod(self, name, scope, group=None):
+        self.delete_pod(name)
         labels = self._labels.copy()
         labels['cluster-name'] = scope
+        if group is not None:
+            labels['citus-group'] = str(group)
         metadata = self._client.V1ObjectMeta(namespace=self._namespace, name=name, labels=labels)
         spec = self._client.V1PodSpec(containers=[self._client.V1Container(name=name, image='empty')])
         body = self._client.V1Pod(metadata=metadata, spec=spec)
@@ -505,15 +646,18 @@ class KubernetesController(AbstractDcsController):
             except Exception:
                 break
 
-    def query(self, key, scope='batman'):
+    def query(self, key, scope='batman', group=None):
         if key.startswith('members/'):
             pod = self._api.read_namespaced_pod(key[8:], self._namespace)
             return (pod.metadata.annotations or {}).get('status', '')
         else:
             try:
-                ep = scope + {'leader': '', 'history': '-config', 'initialize': '-config'}.get(key, '-' + key)
+                if group is not None:
+                    scope = '{0}-{1}'.format(scope, group)
+                rkey = 'leader' if key in ('status', 'failsafe') else key
+                ep = scope + {'leader': '', 'history': '-config', 'initialize': '-config'}.get(rkey, '-' + rkey)
                 e = self._api.read_namespaced_endpoints(ep, self._namespace)
-                if key != 'sync':
+                if key not in ('sync', 'status', 'failsafe'):
                     return e.metadata.annotations[key]
                 else:
                     return json.dumps(e.metadata.annotations)
@@ -535,11 +679,8 @@ class KubernetesController(AbstractDcsController):
             if len(result.items) < 1:
                 break
 
-    def _is_running(self):
-        return True
 
-
-class ZooKeeperController(AbstractDcsController):
+class ZooKeeperController(AbstractExternalDcsController):
 
     """ handles all zookeeper related tasks, used for the tests setup and cleanup """
 
@@ -551,13 +692,13 @@ class ZooKeeperController(AbstractDcsController):
         import kazoo.client
         self._client = kazoo.client.KazooClient()
 
-    def _start(self):
-        pass  # TODO: implement later
+    def process_name(self):
+        return "java .*zookeeper"
 
-    def query(self, key, scope='batman'):
+    def query(self, key, scope='batman', group=None):
         import kazoo.exceptions
         try:
-            return self._client.get(self.path(key, scope))[0].decode('utf-8')
+            return self._client.get(self.path(key, scope, group))[0].decode('utf-8')
         except kazoo.exceptions.NoNodeError:
             return None
 
@@ -571,6 +712,9 @@ class ZooKeeperController(AbstractDcsController):
             assert False, "exception when cleaning up zookeeper contents: {0}".format(e)
 
     def _is_running(self):
+        if not super(ZooKeeperController, self)._is_running():
+            return False
+
         # if zookeeper is running, but we didn't start it
         if self._client.connected:
             return True
@@ -620,12 +764,12 @@ class RaftController(AbstractDcsController):
         del env['PATRONI_RAFT_PARTNER_ADDRS']
         env['PATRONI_RAFT_SELF_ADDR'] = self.CONTROLLER_ADDR
         env['PATRONI_RAFT_DATA_DIR'] = self._work_directory
-        return subprocess.Popen([sys.executable, '-m', 'coverage', 'run',
-                                '--source=patroni', '-p', 'patroni_raft_controller.py'],
-                                stdout=self._log, stderr=subprocess.STDOUT, env=env)
+        return psutil.Popen([sys.executable, '-m', 'coverage', 'run',
+                             '--source=patroni', '-p', 'patroni_raft_controller.py'],
+                            stdout=self._log, stderr=subprocess.STDOUT, env=env)
 
-    def query(self, key, scope='batman'):
-        ret = self._raft.get(self.path(key, scope))
+    def query(self, key, scope='batman', group=None):
+        ret = self._raft.get(self.path(key, scope, group))
         return ret and ret['value']
 
     def set(self, key, value):
@@ -651,6 +795,7 @@ class PatroniPoolController(object):
 
     PYTHON = sys.executable.replace('\\', '/')
     BACKUP_SCRIPT = [PYTHON, 'features/backup_create.py']
+    BACKUP_RESTORE_SCRIPT = ' '.join((PYTHON, os.path.abspath('features/backup_restore.py'))).replace('\\', '/')
     ARCHIVE_RESTORE_SCRIPT = ' '.join((PYTHON, os.path.abspath('features/archive-restore.py')))
 
     def __init__(self, context):
@@ -660,8 +805,17 @@ class PatroniPoolController(object):
         self._patroni_path = None
         self._processes = {}
         self.create_and_set_output_directory('')
+        self._check_postgres_ssl()
         self.known_dcs = {subclass.name(): subclass for subclass in AbstractDcsController.get_subclasses()}
 
+    def _check_postgres_ssl(self):
+        try:
+            subprocess.check_output(['postgres', '-D', os.devnull, '-c', 'ssl=on'], stderr=subprocess.STDOUT)
+            raise Exception  # this one should never happen because the previous line will always raise and exception
+        except Exception as e:
+            self._context.postgres_supports_ssl = isinstance(e, subprocess.CalledProcessError)\
+                and 'SSL is not supported by this build' not in e.output.decode()
+
     @property
     def patroni_path(self):
         if self._patroni_path is None:
@@ -685,7 +839,7 @@ class PatroniPoolController(object):
 
     def __getattr__(self, func):
         if func not in ['stop', 'query', 'write_label', 'read_label', 'check_role_has_changed_to',
-                        'add_tag_to_config', 'get_watchdog', 'patroni_hang', 'backup']:
+                        'add_tag_to_config', 'get_watchdog', 'patroni_hang', 'backup', 'read_patroni_log']:
             raise AttributeError("PatroniPoolController instance has no attribute '{0}'".format(func))
 
         def wrapper(name, *args, **kwargs):
@@ -712,7 +866,8 @@ class PatroniPoolController(object):
             'bootstrap': {
                 'method': 'pg_basebackup',
                 'pg_basebackup': {
-                    'command': " ".join(self.BACKUP_SCRIPT) + ' --walmethod=stream --dbname=' + f.backup_source
+                    'command': " ".join(self.BACKUP_SCRIPT
+                                        + ['--walmethod=stream', '--dbname="{0}"'.format(f.backup_source)])
                 },
                 'dcs': {
                     'postgresql': {
@@ -725,9 +880,9 @@ class PatroniPoolController(object):
             'postgresql': {
                 'parameters': {
                     'archive_mode': 'on',
-                    'archive_command': (self.ARCHIVE_RESTORE_SCRIPT + ' --mode archive ' +
-                                        '--dirname {} --filename %f --pathname %p').format(
-                                        os.path.join(self.patroni_path, 'data', 'wal_archive').replace('\\', '/'))
+                    'archive_command': (self.ARCHIVE_RESTORE_SCRIPT + ' --mode archive '
+                                        + '--dirname {} --filename %f --pathname %p')
+                    .format(os.path.join(self.patroni_path, 'data', 'wal_archive_clone').replace('\\', '/'))
                 },
                 'authentication': {
                     'superuser': {'password': 'zalando1'},
@@ -737,22 +892,28 @@ class PatroniPoolController(object):
         }
         self.start(to_name, custom_config=custom_config)
 
+    def backup_restore_config(self, params=None):
+        return {
+            'command': (self.BACKUP_RESTORE_SCRIPT
+                        + ' --sourcedir=' + os.path.join(self.patroni_path, 'data', 'basebackup')).replace('\\', '/'),
+            'test-argument': 'test-value',  # test config mapping approach on custom bootstrap/replica creation
+            **(params or {}),
+        }
+
     def bootstrap_from_backup(self, name, cluster_name):
         custom_config = {
             'scope': cluster_name,
             'bootstrap': {
                 'method': 'backup_restore',
-                'backup_restore': {
-                    'command': (self.PYTHON + ' features/backup_restore.py --sourcedir=' +
-                                os.path.join(self.patroni_path, 'data', 'basebackup').replace('\\', '/')),
+                'backup_restore': self.backup_restore_config({
                     'recovery_conf': {
                         'recovery_target_action': 'promote',
                         'recovery_target_timeline': 'latest',
-                        'restore_command': (self.ARCHIVE_RESTORE_SCRIPT + ' --mode restore ' +
-                                            '--dirname {} --filename %f --pathname %p').format(
-                                            os.path.join(self.patroni_path, 'data', 'wal_archive').replace('\\', '/'))
-                    }
-                }
+                        'restore_command': (self.ARCHIVE_RESTORE_SCRIPT + ' --mode restore '
+                                            + '--dirname {} --filename %f --pathname %p').format(
+                            os.path.join(self.patroni_path, 'data', 'wal_archive_clone').replace('\\', '/'))
+                    },
+                })
             },
             'postgresql': {
                 'authentication': {
@@ -763,6 +924,21 @@ class PatroniPoolController(object):
         }
         self.start(name, custom_config=custom_config)
 
+    def bootstrap_from_backup_no_leader(self, name, cluster_name):
+        custom_config = {
+            'scope': cluster_name,
+            'postgresql': {
+                'recovery_conf': {
+                    'restore_command': (self.ARCHIVE_RESTORE_SCRIPT + ' --mode restore '
+                                        + '--dirname {} --filename %f --pathname %p')
+                    .format(os.path.join(self.patroni_path, 'data', 'wal_archive').replace('\\', '/'))
+                },
+                'create_replica_methods': ['no_leader_bootstrap'],
+                'no_leader_bootstrap': self.backup_restore_config({'no_leader': '1'})
+            }
+        }
+        self.start(name, custom_config=custom_config)
+
     @property
     def dcs(self):
         if self._dcs is None:
@@ -889,13 +1065,38 @@ class WatchdogMonitor(object):
 
 # actions to execute on start/stop of the tests and before running individual features
 def before_all(context):
-    os.environ.update({'PATRONI_RESTAPI_USERNAME': 'username', 'PATRONI_RESTAPI_PASSWORD': 'password'})
-    context.request_executor = PatroniRequest({'ctl': {'auth': os.environ['PATRONI_RESTAPI_USERNAME'] +
-                                               ':' + os.environ['PATRONI_RESTAPI_PASSWORD']}})
     context.ci = os.name == 'nt' or\
         any(a in os.environ for a in ('TRAVIS_BUILD_NUMBER', 'BUILD_NUMBER', 'GITHUB_ACTIONS'))
     context.timeout_multiplier = 5 if context.ci else 1  # MacOS sometimes is VERY slow
     context.pctl = PatroniPoolController(context)
+
+    context.keyfile = os.path.join(context.pctl.output_dir, 'patroni.key')
+    context.certfile = os.path.join(context.pctl.output_dir, 'patroni.crt')
+    try:
+        if sys.platform == 'darwin' and 'GITHUB_ACTIONS' in os.environ:
+            raise Exception
+        with open(os.devnull, 'w') as null:
+            ret = subprocess.call(['openssl', 'req', '-nodes', '-new', '-x509', '-subj', '/CN=batman.patroni',
+                                   '-addext', 'subjectAltName=IP:127.0.0.1', '-keyout', context.keyfile,
+                                   '-out', context.certfile], stdout=null, stderr=null)
+            if ret != 0:
+                raise Exception
+            os.chmod(context.keyfile, stat.S_IWRITE | stat.S_IREAD)
+    except Exception:
+        context.keyfile = context.certfile = None
+
+    os.environ.update({'PATRONI_RESTAPI_USERNAME': 'username', 'PATRONI_RESTAPI_PASSWORD': 'password'})
+    ctl = {'auth': os.environ['PATRONI_RESTAPI_USERNAME'] + ':' + os.environ['PATRONI_RESTAPI_PASSWORD']}
+    if context.certfile:
+        os.environ.update({'PATRONI_RESTAPI_CAFILE': context.certfile,
+                           'PATRONI_RESTAPI_CERTFILE': context.certfile,
+                           'PATRONI_RESTAPI_KEYFILE': context.keyfile,
+                           'PATRONI_RESTAPI_VERIFY_CLIENT': 'required',
+                           'PATRONI_CTL_INSECURE': 'on',
+                           'PATRONI_CTL_CERTFILE': context.certfile,
+                           'PATRONI_CTL_KEYFILE': context.keyfile})
+        ctl.update({'cacert': context.certfile, 'certfile': context.certfile, 'keyfile': context.keyfile})
+    context.request_executor = PatroniRequest({'ctl': ctl}, True)
     context.dcs_ctl = context.pctl.known_dcs[context.pctl.dcs](context)
     context.dcs_ctl.start()
     try:
@@ -914,20 +1115,37 @@ def after_all(context):
 def before_feature(context, feature):
     """ create per-feature output directory to collect Patroni and PostgreSQL logs """
     if feature.name == 'watchdog' and os.name == 'nt':
-        feature.skip("Watchdog isn't supported on Windows")
-    else:
-        context.pctl.create_and_set_output_directory(feature.name)
+        return feature.skip("Watchdog isn't supported on Windows")
+    elif feature.name == 'citus':
+        lib = subprocess.check_output(['pg_config', '--pkglibdir']).decode('utf-8').strip()
+        if not os.path.exists(os.path.join(lib, 'citus.so')):
+            return feature.skip("Citus extenstion isn't available")
+    context.pctl.create_and_set_output_directory(feature.name)
 
 
 def after_feature(context, feature):
-    """ stop all Patronis, remove their data directory and cleanup the keys in etcd """
+    """ send SIGCONT to a dcs if neccessary,
+    stop all Patronis remove their data directory and cleanup the keys in etcd """
+    context.dcs_ctl.stop_outage()
     context.pctl.stop_all()
     data = os.path.join(context.pctl.patroni_path, 'data')
     if os.path.exists(data):
         shutil.rmtree(data)
     context.dcs_ctl.cleanup_service_tree()
-    if feature.status == 'failed':
+
+    found = False
+    logs = glob.glob(context.pctl.output_dir + '/patroni_*.log')
+    for log in logs:
+        with open(log) as f:
+            for line in f:
+                if 'please report it as a BUG' in line:
+                    print(':'.join([log, line.rstrip()]))
+                    found = True
+
+    if feature.status == 'failed' or found:
         shutil.copytree(context.pctl.output_dir, context.pctl.output_dir + '_failed')
+    if found:
+        raise Exception('Unexpected errors in Patroni log files')
 
 
 def before_scenario(context, scenario):
@@ -936,3 +1154,7 @@ def before_scenario(context, scenario):
             if p._conn and p._conn.server_version < 110000:
                 scenario.skip('pg_replication_slot_advance() is not supported on {0}'.format(p._conn.server_version))
                 break
+    if 'dcs-failsafe' in scenario.effective_tags and not context.dcs_ctl._handle:
+        scenario.skip('it is not possible to control state of {0} from tests'.format(context.dcs_ctl.name()))
+    if 'reject-duplicate-name' in scenario.effective_tags and context.dcs_ctl.name() == 'raft':
+        scenario.skip('Flaky test with Raft')

features/ignored_slots.feature

@@ -10,7 +10,7 @@ Feature: ignored slots
     When I shut down postgres1
     And I start postgres1
     Then postgres1 is a leader after 10 seconds
-    And "members/postgres1" key in DCS has role=master after 3 seconds
+    And "members/postgres1" key in DCS has role=master after 10 seconds
     # Make sure Patroni has finished telling Postgres it should be accepting writes.
     And postgres1 role is the primary after 20 seconds
     # 1. Create our test logical replication slot.
@@ -25,37 +25,37 @@ Feature: ignored slots
     # but Patroni can actually end up dropping them almost immediately, so it's helpful
     # to verify they exist before we begin testing whether they persist through failover
     # cycles.
-    Then postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin
+    Then postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin after 2 seconds
 
     When I start postgres0
-    Then "members/postgres0" key in DCS has role=replica after 3 seconds
+    Then "members/postgres0" key in DCS has role=replica after 10 seconds
     And postgres0 role is the secondary after 20 seconds
     # Verify that the replica has advanced beyond the point in the WAL
     # where we created the replication slot so that on the next failover
     # cycle we don't accidentally rewind to before the slot creation.
     And replication works from postgres1 to postgres0 after 20 seconds
     When I shut down postgres1
-    Then "members/postgres0" key in DCS has role=master after 3 seconds
+    Then "members/postgres0" key in DCS has role=master after 10 seconds
 
     # 2. After a failover the server (now a replica) still has the slot.
     When I start postgres1
     Then postgres1 role is the secondary after 20 seconds
-    And "members/postgres1" key in DCS has role=replica after 3 seconds
+    And "members/postgres1" key in DCS has role=replica after 10 seconds
     # give Patroni time to sync replication slots
     And I sleep for 2 seconds
-    And postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin
-    And postgres1 does not have a logical replication slot named dummy_slot
+    And postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin after 2 seconds
+    And postgres1 does not have a replication slot named dummy_slot
 
-    # 3. After a failover the server (now a master) still has the slot.
+    # 3. After a failover the server (now a primary) still has the slot.
     When I shut down postgres0
-    Then "members/postgres1" key in DCS has role=master after 3 seconds
-    And postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin
-    And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin
+    Then "members/postgres1" key in DCS has role=master after 10 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_0 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_1 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_2 with the test_decoding plugin after 2 seconds
+    And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin after 2 seconds

features/patroni_api.feature

@@ -14,9 +14,9 @@ Scenario: check API requests on a stand-alone server
 	Then I receive a response code 200
 	When I issue a GET request to http://127.0.0.1:8008/replica
 	Then I receive a response code 503
-	When I run patronictl.py reinit batman postgres0 --force
-	Then I receive a response returncode 0
-	And I receive a response output "Failed: reinitialize for member postgres0, status code=503, (I am the leader, can not reinitialize)"
+	When I issue a POST request to http://127.0.0.1:8008/reinitialize with {"force": true}
+	Then I receive a response code 503
+	And I receive a response text I am the leader, can not reinitialize
 	When I run patronictl.py switchover batman --master postgres0 --force
 	Then I receive a response returncode 1
 	And I receive a response output "Error: No candidates found to switchover to"
@@ -35,30 +35,30 @@ Scenario: check local configuration reload
 	Then I receive a response code 202
 
 Scenario: check dynamic configuration change via DCS
-	Given I run patronictl.py edit-config -s 'ttl=10' -p 'max_connections=101' --force batman
-	Then I receive a response returncode 0
-	And I receive a response output "+ttl: 10"
+	Given I issue a PATCH request to http://127.0.0.1:8008/config with {"ttl": 20, "postgresql": {"parameters": {"max_connections": "101"}}}
+	Then I receive a response code 200
 	And Response on GET http://127.0.0.1:8008/patroni contains pending_restart after 11 seconds
 	When I issue a GET request to http://127.0.0.1:8008/config
 	Then I receive a response code 200
-	And I receive a response ttl 10
+	And I receive a response ttl 20
 	When I issue a GET request to http://127.0.0.1:8008/patroni
 	Then I receive a response code 200
 	And I receive a response tags {'new_tag': 'new_value'}
 	And I sleep for 4 seconds
 
 Scenario: check the scheduled restart
-	Given I issue a PATCH request to http://127.0.0.1:8008/config with {"postgresql": {"parameters": {"superuser_reserved_connections": "6"}}}
-	Then I receive a response code 200
-		And Response on GET http://127.0.0.1:8008/patroni contains pending_restart after 5 seconds
+	Given I run patronictl.py edit-config -p 'superuser_reserved_connections=6' --force batman
+	Then I receive a response returncode 0
+	And I receive a response output "+    superuser_reserved_connections: 6"
+	And Response on GET http://127.0.0.1:8008/patroni contains pending_restart after 5 seconds
 	Given I issue a scheduled restart at http://127.0.0.1:8008 in 5 seconds with {"role": "replica"}
 	Then I receive a response code 202
-		And I sleep for 8 seconds
-		And Response on GET http://127.0.0.1:8008/patroni contains pending_restart after 10 seconds
+	And I sleep for 8 seconds
+	And Response on GET http://127.0.0.1:8008/patroni contains pending_restart after 10 seconds
 	Given I issue a scheduled restart at http://127.0.0.1:8008 in 5 seconds with {"restart_pending": "True"}
 	Then I receive a response code 202
-		And Response on GET http://127.0.0.1:8008/patroni does not contain pending_restart after 10 seconds
-		And postgres0 role is the primary after 10 seconds
+	And Response on GET http://127.0.0.1:8008/patroni does not contain pending_restart after 10 seconds
+	And postgres0 role is the primary after 10 seconds
 
 Scenario: check API requests for the primary-replica pair in the pause mode
 	Given I start postgres1
@@ -68,6 +68,7 @@ Scenario: check API requests for the primary-replica pair in the pause mode
 	When I kill postmaster on postgres1
 	And I issue a GET request to http://127.0.0.1:8009/replica
 	Then I receive a response code 503
+	And "members/postgres1" key in DCS has state=stopped after 10 seconds
 	When I run patronictl.py restart batman postgres1 --force
 	Then I receive a response returncode 0
 	Then replication works from postgres0 to postgres1 after 20 seconds
@@ -76,15 +77,15 @@ Scenario: check API requests for the primary-replica pair in the pause mode
 	Then I receive a response code 200
 	And I receive a response state running
 	And I receive a response role replica
-	When I run patronictl.py reinit batman postgres1 --force
+	When I run patronictl.py reinit batman postgres1 --force --wait
 	Then I receive a response returncode 0
 	And I receive a response output "Success: reinitialize for member postgres1"
+	And postgres1 role is the secondary after 30 seconds
+	And replication works from postgres0 to postgres1 after 20 seconds
 	When I run patronictl.py restart batman postgres0 --force
 	Then I receive a response returncode 0
 	And I receive a response output "Success: restart on member postgres0"
 	And postgres0 role is the primary after 5 seconds
-	When I sleep for 10 seconds
-	Then postgres1 role is the secondary after 15 seconds
 
 Scenario: check the switchover via the API in the pause mode
 	Given I issue a POST request to http://127.0.0.1:8008/switchover with {"leader": "postgres0", "candidate": "postgres1"}
@@ -94,11 +95,11 @@ Scenario: check the switchover via the API in the pause mode
 	And postgres0 role is the secondary after 10 seconds
 	And replication works from postgres1 to postgres0 after 20 seconds
 	And "members/postgres0" key in DCS has state=running after 10 seconds
-	When I issue a GET request to http://127.0.0.1:8008/master
+	When I issue a GET request to http://127.0.0.1:8008/primary
 	Then I receive a response code 503
 	When I issue a GET request to http://127.0.0.1:8008/replica
 	Then I receive a response code 200
-	When I issue a GET request to http://127.0.0.1:8009/master
+	When I issue a GET request to http://127.0.0.1:8009/primary
 	Then I receive a response code 200
 	When I issue a GET request to http://127.0.0.1:8009/replica
 	Then I receive a response code 503
@@ -116,11 +117,11 @@ Scenario: check the scheduled switchover
 	And postgres1 role is the secondary after 10 seconds
 	And replication works from postgres0 to postgres1 after 25 seconds
 	And "members/postgres1" key in DCS has state=running after 10 seconds
-	When I issue a GET request to http://127.0.0.1:8008/master
+	When I issue a GET request to http://127.0.0.1:8008/primary
 	Then I receive a response code 200
 	When I issue a GET request to http://127.0.0.1:8008/replica
 	Then I receive a response code 503
-	When I issue a GET request to http://127.0.0.1:8009/master
+	When I issue a GET request to http://127.0.0.1:8009/primary
 	Then I receive a response code 503
 	When I issue a GET request to http://127.0.0.1:8009/replica
 	Then I receive a response code 200

features/permanent_slots.feature

@@ -0,0 +1,75 @@
+Feature: permanent slots
+  Scenario: check that physical permanent slots are created
+    Given I start postgres0
+    Then postgres0 is a leader after 10 seconds
+    And there is a non empty initialize key in DCS after 15 seconds
+    When I issue a PATCH request to http://127.0.0.1:8008/config with {"slots":{"test_physical":0,"postgres0":0,"postgres1":0,"postgres3":0},"postgresql":{"parameters":{"wal_level":"logical"}}}
+    Then I receive a response code 200
+    And Response on GET http://127.0.0.1:8008/config contains slots after 10 seconds
+    When I start postgres1
+    And I start postgres2
+    And I configure and start postgres3 with a tag replicatefrom postgres2
+    Then postgres0 has a physical replication slot named test_physical after 10 seconds
+    And postgres0 has a physical replication slot named postgres1 after 10 seconds
+    And postgres0 has a physical replication slot named postgres2 after 10 seconds
+    And postgres2 has a physical replication slot named postgres3 after 10 seconds
+
+  @slot-advance
+  Scenario: check that logical permanent slots are created
+    Given I run patronictl.py restart batman postgres0 --force
+    And I issue a PATCH request to http://127.0.0.1:8008/config with {"slots":{"test_logical":{"type":"logical","database":"postgres","plugin":"test_decoding"}}}
+    Then postgres0 has a logical replication slot named test_logical with the test_decoding plugin after 10 seconds
+
+  @slot-advance
+  Scenario: check that permanent slots are created on replicas
+    Given postgres1 has a logical replication slot named test_logical with the test_decoding plugin after 10 seconds
+    Then Logical slot test_logical is in sync between postgres0 and postgres1 after 10 seconds
+    And Logical slot test_logical is in sync between postgres0 and postgres2 after 10 seconds
+    And Logical slot test_logical is in sync between postgres0 and postgres3 after 10 seconds
+    And postgres1 has a physical replication slot named test_physical after 2 seconds
+    And postgres2 has a physical replication slot named test_physical after 2 seconds
+    And postgres3 has a physical replication slot named test_physical after 2 seconds
+
+  @slot-advance
+  Scenario: check permanent physical slots that match with member names
+    Given postgres0 has a physical replication slot named postgres3 after 2 seconds
+    And postgres1 has a physical replication slot named postgres0 after 2 seconds
+    And postgres1 has a physical replication slot named postgres3 after 2 seconds
+    And postgres2 has a physical replication slot named postgres0 after 2 seconds
+    And postgres2 has a physical replication slot named postgres3 after 2 seconds
+    And postgres2 has a physical replication slot named postgres1 after 2 seconds
+    And postgres1 does not have a replication slot named postgres2
+    And postgres3 does not have a replication slot named postgres2
+
+  @slot-advance
+  Scenario: check that permanent slots are advanced on replicas
+    Given I add the table replicate_me to postgres0
+    When I get all changes from logical slot test_logical on postgres0
+    And I get all changes from physical slot test_physical on postgres0
+    Then Logical slot test_logical is in sync between postgres0 and postgres1 after 10 seconds
+    And Physical slot test_physical is in sync between postgres0 and postgres1 after 10 seconds
+    And Logical slot test_logical is in sync between postgres0 and postgres2 after 10 seconds
+    And Physical slot test_physical is in sync between postgres0 and postgres2 after 10 seconds
+    And Logical slot test_logical is in sync between postgres0 and postgres3 after 10 seconds
+    And Physical slot test_physical is in sync between postgres0 and postgres3 after 10 seconds
+    And Physical slot postgres1 is in sync between postgres0 and postgres2 after 10 seconds
+    And Physical slot postgres3 is in sync between postgres2 and postgres0 after 20 seconds
+    And Physical slot postgres3 is in sync between postgres2 and postgres1 after 10 seconds
+    And postgres1 does not have a replication slot named postgres2
+    And postgres3 does not have a replication slot named postgres2
+
+  @slot-advance
+  Scenario: check that only permanent slots are written to the /status key
+    Given "status" key in DCS has test_physical in slots
+    And "status" key in DCS has postgres0 in slots
+    And "status" key in DCS has postgres1 in slots
+    And "status" key in DCS does not have postgres2 in slots
+    And "status" key in DCS has postgres3 in slots
+
+  Scenario: check permanent physical replication slot after failover
+    Given I shut down postgres3
+    And I shut down postgres2
+    And I shut down postgres0
+    Then postgres1 has a physical replication slot named test_physical after 10 seconds
+    And postgres1 has a physical replication slot named postgres0 after 10 seconds
+    And postgres1 has a physical replication slot named postgres3 after 10 seconds

features/priority_failover.feature

@@ -0,0 +1,39 @@
+Feature: priority replication
+  We should check that we can give nodes priority during failover
+
+  Scenario: check failover priority 0 prevents leaderships
+    Given I configure and start postgres0 with a tag failover_priority 1
+    And I configure and start postgres1 with a tag failover_priority 0
+    Then replication works from postgres0 to postgres1 after 20 seconds
+    When I shut down postgres0
+    And there is one of ["following a different leader because I am not allowed to promote"] INFO in the postgres1 patroni log after 5 seconds
+    Then postgres1 role is the secondary after 10 seconds
+    When I start postgres0
+    Then postgres0 role is the primary after 10 seconds
+
+  Scenario: check higher failover priority is respected
+    Given I configure and start postgres2 with a tag failover_priority 1
+    And I configure and start postgres3 with a tag failover_priority 2
+    Then replication works from postgres0 to postgres2 after 20 seconds
+    And replication works from postgres0 to postgres3 after 20 seconds
+    When I shut down postgres0
+    Then postgres3 role is the primary after 10 seconds
+    And there is one of ["postgres3 has equally tolerable WAL position and priority 2, while this node has priority 1","Wal position of postgres3 is ahead of my wal position"] INFO in the postgres2 patroni log after 5 seconds
+
+ Scenario: check conflicting configuration handling
+    When I set nofailover tag in postgres2 config
+    And I issue an empty POST request to http://127.0.0.1:8010/reload
+    Then I receive a response code 202
+    And there is one of ["Conflicting configuration between nofailover: True and failover_priority: 1. Defaulting to nofailover: True"] WARNING in the postgres2 patroni log after 5 seconds
+    And "members/postgres2" key in DCS has tags={'failover_priority': '1', 'nofailover': True} after 10 seconds
+    When I issue a POST request to http://127.0.0.1:8010/failover with {"candidate": "postgres2"}
+    Then I receive a response code 412
+    And I receive a response text "failover is not possible: no good candidates have been found"
+    When I reset nofailover tag in postgres1 config
+    And I issue an empty POST request to http://127.0.0.1:8009/reload
+    Then I receive a response code 202
+    And there is one of ["Conflicting configuration between nofailover: False and failover_priority: 0. Defaulting to nofailover: False"] WARNING in the postgres1 patroni log after 5 seconds
+    And "members/postgres1" key in DCS has tags={'failover_priority': '0', 'nofailover': False} after 10 seconds
+    And I issue a POST request to http://127.0.0.1:8009/failover with {"candidate": "postgres1"}
+    Then I receive a response code 200
+    And postgres1 role is the primary after 10 seconds

features/recovery.feature

@@ -0,0 +1,26 @@
+Feature: recovery
+  We want to check that crashed postgres is started back
+
+  Scenario: check that timeline is not incremented when primary is started after crash
+    Given I start postgres0
+    Then postgres0 is a leader after 10 seconds
+    And there is a non empty initialize key in DCS after 15 seconds
+    When I start postgres1
+    And I add the table foo to postgres0
+    Then table foo is present on postgres1 after 20 seconds
+    When I kill postmaster on postgres0
+    Then postgres0 role is the primary after 10 seconds
+    When I issue a GET request to http://127.0.0.1:8008/
+    Then I receive a response code 200
+    And I receive a response role master
+    And I receive a response timeline 1
+    And "members/postgres0" key in DCS has state=running after 12 seconds
+    And replication works from postgres0 to postgres1 after 15 seconds
+
+  Scenario: check immediate failover when master_start_timeout=0
+    Given I issue a PATCH request to http://127.0.0.1:8008/config with {"master_start_timeout": 0}
+    Then I receive a response code 200
+    And Response on GET http://127.0.0.1:8008/config contains master_start_timeout after 10 seconds
+    When I kill postmaster on postgres0
+    Then postgres1 is a leader after 10 seconds
+    And postgres1 role is the primary after 10 seconds

features/standby_cluster.feature

@@ -13,14 +13,15 @@ Feature: standby cluster
     When I start postgres0
     Then "members/postgres0" key in DCS has state=running after 10 seconds
     And replication works from postgres1 to postgres0 after 15 seconds
+    When I issue a GET request to http://127.0.0.1:8008/patroni
+    Then I receive a response code 200
+    And I receive a response replication_state streaming
+    And "members/postgres0" key in DCS has replication_state=streaming after 10 seconds
 
   @slot-advance
   Scenario: check permanent logical slots are synced to the replica
     Given I run patronictl.py restart batman postgres1 --force
     Then Logical slot test_logical is in sync between postgres0 and postgres1 after 10 seconds
-    When I add the table replicate_me to postgres1
-    And I get all changes from logical slot test_logical on postgres1
-    Then Logical slot test_logical is in sync between postgres0 and postgres1 after 10 seconds
 
   Scenario: Detach exiting node from the cluster
     When I shut down postgres1
@@ -34,8 +35,11 @@ Feature: standby cluster
     Then postgres1 is a leader of batman1 after 10 seconds
     When I add the table foo to postgres0
     Then table foo is present on postgres1 after 20 seconds
+    When I issue a GET request to http://127.0.0.1:8009/patroni
+    Then I receive a response code 200
+    And I receive a response replication_state streaming
     And I sleep for 3 seconds
-    When I issue a GET request to http://127.0.0.1:8009/master
+    When I issue a GET request to http://127.0.0.1:8009/primary
     Then I receive a response code 503
     When I issue a GET request to http://127.0.0.1:8009/standby_leader
     Then I receive a response code 200
@@ -44,17 +48,24 @@ Feature: standby cluster
     When I start postgres2 in a cluster batman1
     Then postgres2 role is the replica after 24 seconds
     And table foo is present on postgres2 after 20 seconds
-    And postgres1 does not have a logical replication slot named test_logical
+    When I issue a GET request to http://127.0.0.1:8010/patroni
+    Then I receive a response code 200
+    And I receive a response replication_state streaming
+    And postgres1 does not have a replication slot named test_logical
+
+  Scenario: check switchover
+    Given I run patronictl.py switchover batman1 --force
+    Then Status code on GET http://127.0.0.1:8010/standby_leader is 200 after 10 seconds
+    And postgres1 is replicating from postgres2 after 32 seconds
+    And there is a postgres2_cb.log with "on_start replica batman1\non_role_change standby_leader batman1" in postgres2 data directory
 
   Scenario: check failover
-    When I kill postgres1
-    And I kill postmaster on postgres1
-    Then postgres2 is replicating from postgres0 after 32 seconds
-    When I issue a GET request to http://127.0.0.1:8010/master
+    When I kill postgres2
+    And I kill postmaster on postgres2
+    Then postgres1 is replicating from postgres0 after 32 seconds
+    And Status code on GET http://127.0.0.1:8009/standby_leader is 200 after 10 seconds
+    When I issue a GET request to http://127.0.0.1:8009/primary
     Then I receive a response code 503
-    And I sleep for 3 seconds
-    When I issue a GET request to http://127.0.0.1:8010/standby_leader
-    Then I receive a response code 200
     And I receive a response role standby_leader
-    And replication works from postgres0 to postgres2 after 15 seconds
-    And there is a postgres2_cb.log with "on_start replica batman1\non_role_change standby_leader batman1" in postgres2 data directory
+    And replication works from postgres0 to postgres1 after 15 seconds
+    And there is a postgres1_cb.log with "on_role_change replica batman1\non_role_change standby_leader batman1" in postgres1 data directory

features/steps/basic_replication.py

@@ -1,3 +1,4 @@
+import json
 import patroni.psycopg as pg
 
 from behave import step, then
@@ -9,6 +10,22 @@ def start_patroni(context, name):
     return context.pctl.start(name)
 
 
+@step('I start duplicate {name:w} on port {port:d}')
+def start_duplicate_patroni(context, name, port):
+    config = {
+        "name": name,
+        "restapi": {
+            "listen": "127.0.0.1:{0}".format(port)
+        }
+    }
+    try:
+        context.pctl.start('dup-' + name, custom_config=config)
+        assert False, "Process was expected to fail"
+    except AssertionError as e:
+        assert 'is not running after being started' in str(e), \
+            "No error was raised by duplicate start of {0} ".format(name)
+
+
 @step('I shut down {name:w}')
 def stop_patroni(context, name):
     return context.pctl.stop(name, timeout=60)
@@ -19,16 +36,21 @@ def kill_patroni(context, name):
     return context.pctl.stop(name, kill=True)
 
 
-@step('I kill postmaster on {name:w}')
+@step('I shut down postmaster on {name:w}')
 def stop_postgres(context, name):
     return context.pctl.stop(name, postgres=True)
 
 
+@step('I kill postmaster on {name:w}')
+def kill_postgres(context, name):
+    return context.pctl.stop(name, kill=True, postgres=True)
+
+
 @step('I add the table {table_name:w} to {pg_name:w}')
 def add_table(context, table_name, pg_name):
     # parse the configuration file and get the port
     try:
-        context.pctl.query(pg_name, "CREATE TABLE {0}()".format(table_name))
+        context.pctl.query(pg_name, "CREATE TABLE public.{0}()".format(table_name))
     except pg.Error as e:
         assert False, "Error creating table {0} on {1}: {2}".format(table_name, pg_name, e)
 
@@ -37,9 +59,9 @@ def add_table(context, table_name, pg_name):
 def toggle_wal_replay(context, action, pg_name):
     # pause or resume the wal replay process
     try:
-       version = context.pctl.query(pg_name, "select pg_catalog.pg_read_file('PG_VERSION', 0, 2)").fetchone()
-       wal = version and version[0] and int(version[0].split('.')[0]) < 10 and "xlog" or "wal"
-       context.pctl.query(pg_name, "SELECT pg_{0}_replay_{1}()".format(wal, action))
+        version = context.pctl.query(pg_name, "SHOW server_version_num").fetchone()[0]
+        wal_name = 'xlog' if int(version) / 10000 < 10 else 'wal'
+        context.pctl.query(pg_name, "SELECT pg_{0}_replay_{1}()".format(wal_name, action))
     except pg.Error as e:
         assert False, "Error during {0} wal recovery on {1}: {2}".format(action, pg_name, e)
 
@@ -47,10 +69,10 @@ def toggle_wal_replay(context, action, pg_name):
 @step('I {action:w} table on {pg_name:w}')
 def crdr_mytest(context, action, pg_name):
     try:
-       if (action == "create"):
-           context.pctl.query(pg_name, "create table if not exists mytest(id Numeric)")
-       else:
-           context.pctl.query(pg_name, "drop table if exists mytest")
+        if (action == "create"):
+            context.pctl.query(pg_name, "create table if not exists public.mytest(id numeric)")
+        else:
+            context.pctl.query(pg_name, "drop table if exists public.mytest")
     except pg.Error as e:
         assert False, "Error {0} table mytest on {1}: {2}".format(action, pg_name, e)
 
@@ -59,7 +81,7 @@ def crdr_mytest(context, action, pg_name):
 def initiate_load(context, pg_name):
     # perform dummy load
     try:
-       context.pctl.query(pg_name, "begin; insert into mytest select r::numeric from generate_series(1, 350000) r; commit;")
+        context.pctl.query(pg_name, "insert into public.mytest select r::numeric from generate_series(1, 350000) r")
     except pg.Error as e:
         assert False, "Error loading test data on {0}: {1}".format(pg_name, e)
 
@@ -68,25 +90,39 @@ def initiate_load(context, pg_name):
 def table_is_present_on(context, table_name, pg_name, max_replication_delay):
     max_replication_delay *= context.timeout_multiplier
     for _ in range(int(max_replication_delay)):
-        if context.pctl.query(pg_name, "SELECT 1 FROM {0}".format(table_name), fail_ok=True) is not None:
+        if context.pctl.query(pg_name, "SELECT 1 FROM public.{0}".format(table_name), fail_ok=True) is not None:
             break
         sleep(1)
     else:
-        assert False,\
+        assert False, \
             "Table {0} is not present on {1} after {2} seconds".format(table_name, pg_name, max_replication_delay)
 
 
 @then('{pg_name:w} role is the {pg_role:w} after {max_promotion_timeout:d} seconds')
 def check_role(context, pg_name, pg_role, max_promotion_timeout):
     max_promotion_timeout *= context.timeout_multiplier
-    assert context.pctl.check_role_has_changed_to(pg_name, pg_role, timeout=int(max_promotion_timeout)),\
+    assert context.pctl.check_role_has_changed_to(pg_name, pg_role, timeout=int(max_promotion_timeout)), \
         "{0} role didn't change to {1} after {2} seconds".format(pg_name, pg_role, max_promotion_timeout)
 
 
-@step('replication works from {master:w} to {replica:w} after {time_limit:d} seconds')
-@then('replication works from {master:w} to {replica:w} after {time_limit:d} seconds')
-def replication_works(context, master, replica, time_limit):
+@step('replication works from {primary:w} to {replica:w} after {time_limit:d} seconds')
+@then('replication works from {primary:w} to {replica:w} after {time_limit:d} seconds')
+def replication_works(context, primary, replica, time_limit):
     context.execute_steps(u"""
         When I add the table test_{0} to {1}
         Then table test_{0} is present on {2} after {3} seconds
-    """.format(int(time()), master, replica, time_limit))
+    """.format(str(time()).replace('.', '_').replace(',', '_'), primary, replica, time_limit))
+
+
+@step('there is one of {message_list} {level:w} in the {node} patroni log after {timeout:d} seconds')
+def check_patroni_log(context, message_list, level, node, timeout):
+    timeout *= context.timeout_multiplier
+    message_list = json.loads(message_list)
+
+    for _ in range(int(timeout)):
+        messsages_of_level = context.pctl.read_patroni_log(node, level)
+        if any(any(message in line for line in messsages_of_level) for message in message_list):
+            break
+        sleep(1)
+    else:
+        assert False, f"There were none of {message_list} {level} in the {node} patroni log after {timeout} seconds"

features/steps/cascading_replication.py

@@ -11,11 +11,8 @@ def start_patroni_with_a_name_value_tag(context, name, tag_name, tag_value):
 
 @then('There is a {label} with "{content}" in {name:w} data directory')
 def check_label(context, label, content, name):
-    label = context.pctl.read_label(name, label)
-    if label is None:
-        label = ""
-    label = label.replace('\n', '\\n')
-    assert content in label, "\"{0}\" doesn't contain {1}".format(label, content)
+    value = (context.pctl.read_label(name, label) or '').replace('\n', '\\n')
+    assert content in value, "\"{0}\" in {1} doesn't contain {2}".format(value, label, content)
 
 
 @step('I create label with "{content:w}" in {name:w} data directory')
@@ -31,7 +28,7 @@ def check_member(context, name, key, value, time_limit):
     while time.time() < max_time:
         try:
             response = json.loads(context.dcs_ctl.query(name))
-            dcs_value = response.get(key)
+            dcs_value = str(response.get(key))
             if dcs_value == value:
                 return
         except Exception:

features/steps/citus.py

@@ -0,0 +1,135 @@
+import json
+import time
+
+from behave import step, then
+from dateutil import tz
+from datetime import datetime
+from functools import partial
+from threading import Thread, Event
+
+tzutc = tz.tzutc()
+
+
+@step('{name:w} is a leader in a group {group:d} after {time_limit:d} seconds')
+@then('{name:w} is a leader in a group {group:d} after {time_limit:d} seconds')
+def is_a_group_leader(context, name, group, time_limit):
+    time_limit *= context.timeout_multiplier
+    max_time = time.time() + int(time_limit)
+    while (context.dcs_ctl.query("leader", group=group) != name):
+        time.sleep(1)
+        assert time.time() < max_time, "{0} is not a leader in dcs after {1} seconds".format(name, time_limit)
+
+
+@step('"{name}" key in a group {group:d} in DCS has {key:w}={value} after {time_limit:d} seconds')
+def check_group_member(context, name, group, key, value, time_limit):
+    time_limit *= context.timeout_multiplier
+    max_time = time.time() + int(time_limit)
+    dcs_value = None
+    response = None
+    while time.time() < max_time:
+        try:
+            response = json.loads(context.dcs_ctl.query(name, group=group))
+            dcs_value = response.get(key)
+            if dcs_value == value:
+                return
+        except Exception:
+            pass
+        time.sleep(1)
+    assert False, ("{0} in a group {1} does not have {2}={3} (found {4}) in dcs"
+                   " after {5} seconds").format(name, group, key, value, response, time_limit)
+
+
+@step('I start {name:w} in citus group {group:d}')
+def start_citus(context, name, group):
+    return context.pctl.start(name, custom_config={"citus": {"database": "postgres", "group": int(group)}})
+
+
+@step('{name1:w} is registered in the {name2:w} as the {role:w} in group {group:d} after {time_limit:d} seconds')
+def check_registration(context, name1, name2, role, group, time_limit):
+    time_limit *= context.timeout_multiplier
+    max_time = time.time() + int(time_limit)
+
+    worker_port = int(context.pctl.query(name1, "SHOW port").fetchone()[0])
+
+    while time.time() < max_time:
+        try:
+            cur = context.pctl.query(name2, "SELECT nodeport, noderole"
+                                            " FROM pg_catalog.pg_dist_node WHERE groupid = {0}".format(group))
+            mapping = {r[0]: r[1] for r in cur}
+            if mapping.get(worker_port) == role:
+                return
+        except Exception:
+            pass
+        time.sleep(1)
+    assert False, "Node {0} is not registered in pg_dist_node on the node {1}".format(name1, name2)
+
+
+@step('I create a distributed table on {name:w}')
+def create_distributed_table(context, name):
+    context.pctl.query(name, 'CREATE TABLE public.d(id int not null)')
+    context.pctl.query(name, "SELECT create_distributed_table('public.d', 'id')")
+
+
+@step('I cleanup a distributed table on {name:w}')
+def cleanup_distributed_table(context, name):
+    context.pctl.query(name, 'TRUNCATE public.d')
+
+
+def insert_thread(query_func, context):
+    while True:
+        if context.thread_stop_event.is_set():
+            break
+
+        context.insert_counter += 1
+        query_func('INSERT INTO public.d VALUES({0})'.format(context.insert_counter))
+
+        context.thread_stop_event.wait(0.01)
+
+
+@step('I start a thread inserting data on {name:w}')
+def start_insert_thread(context, name):
+    context.thread_stop_event = Event()
+    context.insert_counter = 0
+    query_func = partial(context.pctl.query, name)
+    thread_func = partial(insert_thread, query_func, context)
+    context.thread = Thread(target=thread_func)
+    context.thread.daemon = True
+    context.thread.start()
+
+
+@then('a thread is still alive')
+def thread_is_alive(context):
+    assert context.thread.is_alive(), "Thread is not alive"
+
+
+@step("I stop a thread")
+def stop_insert_thread(context):
+    context.thread_stop_event.set()
+    context.thread.join(1 * context.timeout_multiplier)
+    assert not context.thread.is_alive(), "Thread is still alive"
+
+
+@step("a distributed table on {name:w} has expected rows")
+def count_rows(context, name):
+    rows = context.pctl.query(name, "SELECT COUNT(*) FROM public.d").fetchone()[0]
+    assert rows == context.insert_counter, "Distributed table doesn't have expected amount of rows"
+
+
+@step("there is a transaction in progress on {name:w} changing pg_dist_node after {time_limit:d} seconds")
+def check_transaction(context, name, time_limit):
+    time_limit *= context.timeout_multiplier
+    max_time = time.time() + int(time_limit)
+    while time.time() < max_time:
+        cur = context.pctl.query(name, "SELECT xact_start FROM pg_stat_activity WHERE pid <> pg_backend_pid()"
+                                       " AND state = 'idle in transaction' AND query ~ 'citus_update_node'")
+        if cur.rowcount == 1:
+            context.xact_start = cur.fetchone()[0]
+            return
+        time.sleep(1)
+    assert False, f"There is no idle in transaction on {name} updating pg_dist_node after {time_limit} seconds"
+
+
+@step("a transaction finishes in {timeout:d} seconds")
+def check_transaction_timeout(context, timeout):
+    assert (datetime.now(tzutc) - context.xact_start).seconds >= timeout, \
+        "a transaction finished earlier than in {0} seconds".format(timeout)

features/steps/dcs_failsafe_mode.py

@@ -0,0 +1,16 @@
+from behave import step
+
+
+@step('DCS is down')
+def start_dcs_outage(context):
+    context.dcs_ctl.start_outage()
+
+
+@step('DCS is up')
+def stop_dcs_outage(context):
+    context.dcs_ctl.stop_outage()
+
+
+@step('I start {name:w} in a cluster {cluster_name:w} from backup with no_leader')
+def start_cluster_from_backup_no_leader(context, name, cluster_name):
+    context.pctl.bootstrap_from_backup_no_leader(name, cluster_name)

features/steps/patroni_api.py

@@ -1,5 +1,4 @@
 import json
-import os
 import parse
 import shlex
 import subprocess
@@ -71,6 +70,8 @@ def do_post_empty(context, url):
 
 @step('I issue a {request_method:w} request to {url:url} with {data}')
 def do_request(context, request_method, url, data):
+    if context.certfile:
+        url = url.replace('http://', 'https://')
     data = data and json.loads(data)
     try:
         r = context.request_executor.request(request_method, url, data)
@@ -86,10 +87,7 @@ def do_request(context, request_method, url, data):
 def do_run(context, cmd):
     cmd = [sys.executable, '-m', 'coverage', 'run', '--source=patroni', '-p'] + shlex.split(cmd)
     try:
-        # XXX: Dirty hack! We need to take name/passwd from the config!
-        env = os.environ.copy()
-        env.update({'PATRONI_RESTAPI_USERNAME': 'username', 'PATRONI_RESTAPI_PASSWORD': 'password'})
-        response = subprocess.check_output(cmd, stderr=subprocess.STDOUT, env=env)
+        response = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
         context.status_code = 0
     except subprocess.CalledProcessError as e:
         response = e.output
@@ -100,7 +98,7 @@ def do_run(context, cmd):
 @then('I receive a response {component:w} {data}')
 def check_response(context, component, data):
     if component == 'code':
-        assert context.status_code == int(data),\
+        assert context.status_code == int(data), \
             "status code {0} != {1}, response: {2}".format(context.status_code, data, context.response)
     elif component == 'returncode':
         assert context.status_code == int(data), "return code {0} != {1}, {2}".format(context.status_code,
@@ -111,6 +109,8 @@ def check_response(context, component, data):
         assert data.strip('"') in context.response, "response {0} does not contain {1}".format(context.response, data)
     else:
         assert component in context.response, "{0} is not part of the response".format(component)
+        if context.certfile:
+            data = data.replace('http://', 'https://')
         assert str(context.response[component]) == str(data), "{0} does not contain {1}".format(component, data)
 
 
@@ -128,13 +128,35 @@ def scheduled_restart(context, url, in_seconds, data):
     context.execute_steps(u"""Given I issue a POST request to {0}/restart with {1}""".format(url, json.dumps(data)))
 
 
+@step('I {action:w} {tag:w} tag in {pg_name:w} config')
+def add_bool_tag_to_config(context, action, tag, pg_name):
+    value = action == 'set'
+    context.pctl.add_tag_to_config(pg_name, tag, value)
+
+
 @step('I add tag {tag:w} {value:w} to {pg_name:w} config')
 def add_tag_to_config(context, tag, value, pg_name):
     context.pctl.add_tag_to_config(pg_name, tag, value)
 
 
-@then('Response on GET {url} contains {value} after {timeout:d} seconds')
+@then('Status code on GET {url:url} is {code:d} after {timeout:d} seconds')
+def check_http_code(context, url, code, timeout):
+    if context.certfile:
+        url = url.replace('http://', 'https://')
+    timeout *= context.timeout_multiplier
+    for _ in range(int(timeout)):
+        r = context.request_executor.request('GET', url)
+        if int(code) == int(r.status):
+            break
+        time.sleep(1)
+    else:
+        assert False, "HTTP Status Code is not {0} after {1} seconds".format(code, timeout)
+
+
+@then('Response on GET {url:url} contains {value} after {timeout:d} seconds')
 def check_http_response(context, url, value, timeout, negate=False):
+    if context.certfile:
+        url = url.replace('http://', 'https://')
     timeout *= context.timeout_multiplier
     for _ in range(int(timeout)):
         r = context.request_executor.request('GET', url)
@@ -142,7 +164,7 @@ def check_http_response(context, url, value, timeout, negate=False):
             break
         time.sleep(1)
     else:
-        assert False,\
+        assert False, \
             "Value {0} is {1} present in response after {2} seconds".format(value, "not" if not negate else "", timeout)
 
 

features/steps/slots.py

@@ -1,3 +1,4 @@
+import json
 import time
 
 from behave import step, then
@@ -15,21 +16,30 @@ def create_logical_replication_slot(context, slot_name, pg_name, plugin):
         assert False, "Error creating slot {0} on {1} with plugin {2}".format(slot_name, pg_name, plugin)
 
 
-@then('{pg_name:w} has a logical replication slot named {slot_name} with the {plugin:w} plugin')
-def has_logical_replication_slot(context, pg_name, slot_name, plugin):
-    try:
-        row = context.pctl.query(pg_name, ("SELECT slot_type, plugin FROM pg_replication_slots"
-                                           " WHERE slot_name = '{0}'").format(slot_name)).fetchone()
-        assert row, "Couldn't find replication slot named {0}".format(slot_name)
-        assert row[0] == "logical", "Found replication slot named {0} but wasn't a logical slot".format(slot_name)
-        assert row[1] == plugin, ("Found replication slot named {0} but was using plugin "
-                                  "{1} rather than {2}").format(slot_name, row[1], plugin)
-    except pg.Error:
-        assert False, "Error looking for slot {0} on {1} with plugin {2}".format(slot_name, pg_name, plugin)
+@step('{pg_name:w} has a logical replication slot named {slot_name}'
+      ' with the {plugin:w} plugin after {time_limit:d} seconds')
+@then('{pg_name:w} has a logical replication slot named {slot_name}'
+      ' with the {plugin:w} plugin after {time_limit:d} seconds')
+def has_logical_replication_slot(context, pg_name, slot_name, plugin, time_limit):
+    time_limit *= context.timeout_multiplier
+    max_time = time.time() + int(time_limit)
+    while time.time() < max_time:
+        try:
+            row = context.pctl.query(pg_name, ("SELECT slot_type, plugin FROM pg_replication_slots"
+                                               f" WHERE slot_name = '{slot_name}'")).fetchone()
+            if row:
+                assert row[0] == "logical", f"Replication slot {slot_name} isn't a logical but {row[0]}"
+                assert row[1] == plugin, f"Replication slot {slot_name} using plugin {row[1]} rather than {plugin}"
+                return
+        except Exception:
+            pass
+        time.sleep(1)
+    assert False, f"Error looking for slot {slot_name} on {pg_name} with plugin {plugin}"
 
 
-@then('{pg_name:w} does not have a logical replication slot named {slot_name}')
-def does_not_have_logical_replication_slot(context, pg_name, slot_name):
+@step('{pg_name:w} does not have a replication slot named {slot_name:w}')
+@then('{pg_name:w} does not have a replication slot named {slot_name:w}')
+def does_not_have_replication_slot(context, pg_name, slot_name):
     try:
         row = context.pctl.query(pg_name, ("SELECT 1 FROM pg_replication_slots"
                                            " WHERE slot_name = '{0}'").format(slot_name)).fetchone()
@@ -38,13 +48,14 @@ def does_not_have_logical_replication_slot(context, pg_name, slot_name):
         assert False, "Error looking for slot {0} on {1}".format(slot_name, pg_name)
 
 
-@step('Logical slot {slot_name:w} is in sync between {pg_name1:w} and {pg_name2:w} after {time_limit:d} seconds')
-def logical_slots_in_sync(context, slot_name, pg_name1, pg_name2, time_limit):
+@step('{slot_type:w} slot {slot_name:w} is in sync between {pg_name1:w} and {pg_name2:w} after {time_limit:d} seconds')
+def slots_in_sync(context, slot_type, slot_name, pg_name1, pg_name2, time_limit):
     time_limit *= context.timeout_multiplier
     max_time = time.time() + int(time_limit)
+    column = 'confirmed_flush_lsn' if slot_type.lower() == 'logical' else 'restart_lsn'
+    query = f"SELECT {column} FROM pg_replication_slots WHERE slot_name = '{slot_name}'"
     while time.time() < max_time:
         try:
-            query = "SELECT confirmed_flush_lsn FROM pg_replication_slots WHERE slot_name = '{0}'".format(slot_name)
             slot1 = context.pctl.query(pg_name1, query).fetchone()
             slot2 = context.pctl.query(pg_name2, query).fetchone()
             if slot1[0] == slot2[0]:
@@ -52,9 +63,43 @@ def logical_slots_in_sync(context, slot_name, pg_name1, pg_name2, time_limit):
         except Exception:
             pass
         time.sleep(1)
-    assert False, "Logical slot {0} is not in sync between {1} and {2}".format(slot_name, pg_name1, pg_name2)
+    assert False, \
+        f"{slot_type} slot {slot_name} is not in sync between {pg_name1} and {pg_name2} after {time_limit} seconds"
 
 
 @step('I get all changes from logical slot {slot_name:w} on {pg_name:w}')
 def logical_slot_get_changes(context, slot_name, pg_name):
     context.pctl.query(pg_name, "SELECT * FROM pg_logical_slot_get_changes('{0}', NULL, NULL)".format(slot_name))
+
+
+@step('I get all changes from physical slot {slot_name:w} on {pg_name:w}')
+def physical_slot_get_changes(context, slot_name, pg_name):
+    context.pctl.query(pg_name, f"SELECT * FROM pg_replication_slot_advance('{slot_name}', pg_current_wal_lsn())")
+
+
+@step('{pg_name:w} has a physical replication slot named {slot_name} after {time_limit:d} seconds')
+def has_physical_replication_slot(context, pg_name, slot_name, time_limit):
+    time_limit *= context.timeout_multiplier
+    max_time = time.time() + int(time_limit)
+    query = f"SELECT * FROM pg_catalog.pg_replication_slots WHERE slot_type = 'physical' AND slot_name = '{slot_name}'"
+    while time.time() < max_time:
+        try:
+            row = context.pctl.query(pg_name, query).fetchone()
+            if row:
+                return
+        except Exception:
+            pass
+        time.sleep(1)
+    assert False, f"Physical slot {slot_name} doesn't exist after {time_limit} seconds"
+
+
+@step('"{name}" key in DCS has {subkey:w} in {key:w}')
+def dcs_key_contains(context, name, subkey, key):
+    response = json.loads(context.dcs_ctl.query(name))
+    assert key in response and subkey in response[key], f"{name} key in DCS doesn't have {subkey} in {key}"
+
+
+@step('"{name}" key in DCS does not have {subkey:w} in {key:w}')
+def dcs_key_does_not_contain(context, name, subkey, key):
+    response = json.loads(context.dcs_ctl.query(name))
+    assert key not in response or subkey not in response[key], f"{name} key in DCS has {subkey} in {key}"

features/steps/standby_cluster.py

@@ -15,9 +15,7 @@ def start_patroni(context, name, cluster_name):
         "scope": cluster_name,
         "postgresql": {
             "callbacks": callbacks(context, name),
-            "backup_restore": {
-                "command": (context.pctl.PYTHON + " features/backup_restore.py --sourcedir=" +
-                            os.path.join(context.pctl.patroni_path, 'data', 'basebackup').replace('\\', '/'))}
+            "backup_restore": context.pctl.backup_restore_config()
         }
     })
 
@@ -34,6 +32,7 @@ def start_patroni_standby_cluster(context, name, cluster_name, name2):
                 "ttl": 20,
                 "loop_wait": 2,
                 "retry_timeout": 5,
+                "synchronous_mode": True,  # should be completely ignored
                 "standby_cluster": {
                     "host": "localhost",
                     "port": port,

features/steps/watchdog.py

@@ -15,7 +15,7 @@ def polling_loop(timeout, interval=1):
 
 @step('I start {name:w} with watchdog')
 def start_patroni_with_watchdog(context, name):
-    return context.pctl.start(name, custom_config={'watchdog': True})
+    return context.pctl.start(name, custom_config={'watchdog': True, 'bootstrap': {'dcs': {'ttl': 20}}})
 
 
 @step('{name:w} watchdog has been pinged after {timeout:d} seconds')
@@ -31,6 +31,11 @@ def watchdog_was_closed(context, name):
     assert context.pctl.get_watchdog(name).was_closed
 
 
+@step('{name:w} watchdog has a {timeout:d} second timeout')
+def watchdog_has_timeout(context, name, timeout):
+    assert context.pctl.get_watchdog(name).timeout == timeout
+
+
 @step('I reset {name:w} watchdog state')
 def watchdog_reset_pinged(context, name):
     context.pctl.get_watchdog(name).reset()

features/watchdog.feature

@@ -6,6 +6,14 @@ Feature: watchdog
     Then postgres0 is a leader after 10 seconds
     And postgres0 role is the primary after 10 seconds
     And postgres0 watchdog has been pinged after 10 seconds
+    And postgres0 watchdog has a 15 second timeout
+
+  Scenario: watchdog is reconfigured after global ttl changed
+    Given I run patronictl.py edit-config batman -s ttl=30 --force
+    Then I receive a response returncode 0
+    And I receive a response output "+ttl: 30"
+    When I sleep for 4 seconds
+    Then postgres0 watchdog has a 25 second timeout
 
   Scenario: watchdog is disabled during pause
     Given I run patronictl.py pause batman

kubernetes/Dockerfile

@@ -1,17 +1,16 @@
-FROM postgres:15
+FROM postgres:16
 LABEL maintainer="Alexander Kukushkin <[email protected]>"
 
 RUN export DEBIAN_FRONTEND=noninteractive \
     && echo 'APT::Install-Recommends "0";\nAPT::Install-Suggests "0";' > /etc/apt/apt.conf.d/01norecommend \
     && apt-get update -y \
-    && apt-get upgrade -y \
     && apt-cache depends patroni | sed -n -e 's/.* Depends: \(python3-.\+\)$/\1/p' \
             | grep -Ev '^python3-(sphinx|etcd|consul|kazoo|kubernetes)' \
             | xargs apt-get install -y vim-tiny curl jq locales git python3-pip python3-wheel \
     ## Make sure we have a en_US.UTF-8 locale available
     && localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8 \
-    && pip3 install setuptools \
-    && pip3 install 'git+https://github.com/zalando/patroni.git#egg=patroni[kubernetes]' \
+    && pip3 install --break-system-packages setuptools \
+    && pip3 install --break-system-packages 'git+https://github.com/zalando/patroni.git#egg=patroni[kubernetes]' \
     && PGHOME=/home/postgres \
     && mkdir -p $PGHOME \
     && chown postgres $PGHOME \
@@ -25,7 +24,7 @@ RUN export DEBIAN_FRONTEND=noninteractive \
     && apt-get clean -y \
     && rm -rf /var/lib/apt/lists/* /root/.cache
 
-ADD entrypoint.sh /
+COPY entrypoint.sh /
 
 EXPOSE 5432 8008
 ENV LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8 EDITOR=/usr/bin/editor

kubernetes/Dockerfile.citus

@@ -0,0 +1,61 @@
+FROM postgres:16
+LABEL maintainer="Alexander Kukushkin <[email protected]>"
+
+RUN export DEBIAN_FRONTEND=noninteractive \
+    && echo 'APT::Install-Recommends "0";\nAPT::Install-Suggests "0";' > /etc/apt/apt.conf.d/01norecommend \
+    && apt-get update -y \
+    && apt-get upgrade -y \
+    && apt-cache depends patroni | sed -n -e 's/.* Depends: \(python3-.\+\)$/\1/p' \
+            | grep -Ev '^python3-(sphinx|etcd|consul|kazoo|kubernetes)' \
+            | xargs apt-get install -y busybox vim-tiny curl jq less locales git python3-pip python3-wheel lsb-release \
+    ## Make sure we have a en_US.UTF-8 locale available
+    && localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8 \
+    && if [ $(dpkg --print-architecture) = 'arm64' ]; then \
+        apt-get install -y postgresql-server-dev-16 \
+                           gcc make autoconf \
+                           libc6-dev flex libcurl4-gnutls-dev \
+                           libicu-dev libkrb5-dev liblz4-dev \
+                           libpam0g-dev libreadline-dev libselinux1-dev\
+                           libssl-dev libxslt1-dev libzstd-dev uuid-dev \
+        && git clone -b "main" https://github.com/citusdata/citus.git \
+        && MAKEFLAGS="-j $(grep -c ^processor /proc/cpuinfo)" \
+        && cd citus && ./configure && make install && cd ../ && rm -rf /citus; \
+    else \
+        echo "deb [signed-by=/etc/apt/trusted.gpg.d/citusdata_community.gpg] https://packagecloud.io/citusdata/community/debian/ $(lsb_release -cs) main" > /etc/apt/sources.list.d/citusdata_community.list \
+        && curl -sL https://packagecloud.io/citusdata/community/gpgkey | gpg --dearmor > /etc/apt/trusted.gpg.d/citusdata_community.gpg \
+        && apt-get update -y \
+        && apt-get -y install postgresql-16-citus-12.1; \
+    fi \
+    && pip3 install --break-system-packages setuptools \
+    && pip3 install --break-system-packages 'git+https://github.com/zalando/patroni.git#egg=patroni[kubernetes]' \
+    && PGHOME=/home/postgres \
+    && mkdir -p $PGHOME \
+    && chown postgres $PGHOME \
+    && sed -i "s|/var/lib/postgresql.*|$PGHOME:/bin/bash|" /etc/passwd \
+    && /bin/busybox --install -s \
+    # Set permissions for OpenShift
+    && chmod 775 $PGHOME \
+    && chmod 664 /etc/passwd \
+    # Clean up
+    && apt-get remove -y git python3-pip python3-wheel \
+               postgresql-server-dev-16 gcc make autoconf \
+               libc6-dev flex libicu-dev libkrb5-dev liblz4-dev \
+               libpam0g-dev libreadline-dev libselinux1-dev libssl-dev libxslt1-dev libzstd-dev uuid-dev \
+    && apt-get autoremove -y \
+    && apt-get clean -y \
+    && rm -rf /var/lib/apt/lists/* /root/.cache
+
+ADD entrypoint.sh /
+ENV PGSSLMODE=verify-ca PGSSLKEY=/etc/ssl/private/ssl-cert-snakeoil.key PGSSLCERT=/etc/ssl/certs/ssl-cert-snakeoil.pem PGSSLROOTCERT=/etc/ssl/certs/ssl-cert-snakeoil.pem
+
+RUN sed -i 's/^postgresql:/&\n  basebackup:\n    checkpoint: fast/' /entrypoint.sh \
+    && sed -i "s|^    postgresql:|&\n      parameters:\n        max_connections: 100\n        shared_buffers: 16MB\n        ssl: 'on'\n        ssl_ca_file: $PGSSLROOTCERT\n        ssl_cert_file: $PGSSLCERT\n        ssl_key_file: $PGSSLKEY\n        citus.node_conninfo: 'sslrootcert=$PGSSLROOTCERT sslkey=$PGSSLKEY sslcert=$PGSSLCERT sslmode=$PGSSLMODE'|"  /entrypoint.sh \
+    && sed -i 's/^      pg_hba:/&\n      - local all all trust/' /entrypoint.sh \
+    && sed -i "s/^\(.*\) \(.*\) \(.*\) \(.*\) \(.*\) md5.*$/\1 hostssl \3 \4 all md5 clientcert=$PGSSLMODE/" /entrypoint.sh \
+    && sed -i "s#^    \(superuser\|replication\):#&\n      sslmode: $PGSSLMODE\n      sslkey: $PGSSLKEY\n      sslcert: $PGSSLCERT\n      sslrootcert: $PGSSLROOTCERT#" /entrypoint.sh
+
+EXPOSE 5432 8008
+ENV LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8 EDITOR=/usr/bin/editor
+USER postgres
+WORKDIR /home/postgres
+CMD ["/bin/bash", "/entrypoint.sh"]

kubernetes/README.md

@@ -0,0 +1,154 @@
+# Kubernetes deployment examples
+Below you will find examples of Patroni deployments using [kind](https://kind.sigs.k8s.io/).
+
+# Patroni on K8s
+The Patroni cluster deployment with a StatefulSet consisting of three Pods.
+
+Example session:
+
+    $ kind create cluster
+    Creating cluster "kind" ...
+     ✓ Ensuring node image (kindest/node:v1.25.3) 🖼
+     ✓ Preparing nodes 📦
+     ✓ Writing configuration 📜
+     ✓ Starting control-plane 🕹️
+     ✓ Installing CNI 🔌
+     ✓ Installing StorageClass 💾
+    Set kubectl context to "kind-kind"
+    You can now use your cluster with:
+
+    kubectl cluster-info --context kind-kind
+
+    Thanks for using kind! 😊
+
+    $ docker build -t patroni .
+    Sending build context to Docker daemon  138.8kB
+    Step 1/9 : FROM postgres:15
+    ...
+    Successfully built e9bfe69c5d2b
+    Successfully tagged patroni:latest
+
+    $ kind load docker-image patroni
+    Image: "" with ID "sha256:e9bfe69c5d2b319dec0cf564fb895484537664775e18f37f9b707914cc5537e6" not yet present on node "kind-control-plane", loading...
+
+    $ kubectl apply -f patroni_k8s.yaml
+    service/patronidemo-config created
+    statefulset.apps/patronidemo created
+    endpoints/patronidemo created
+    service/patronidemo created
+    service/patronidemo-repl created
+    secret/patronidemo created
+    serviceaccount/patronidemo created
+    role.rbac.authorization.k8s.io/patronidemo created
+    rolebinding.rbac.authorization.k8s.io/patronidemo created
+    clusterrole.rbac.authorization.k8s.io/patroni-k8s-ep-access created
+    clusterrolebinding.rbac.authorization.k8s.io/patroni-k8s-ep-access created
+
+    $ kubectl get pods -L role
+    NAME            READY   STATUS    RESTARTS   AGE   ROLE
+    patronidemo-0   1/1     Running   0          34s   master
+    patronidemo-1   1/1     Running   0          30s   replica
+    patronidemo-2   1/1     Running   0          26s   replica
+
+    $ kubectl exec -ti patronidemo-0 -- bash
+    postgres@patronidemo-0:~$ patronictl list
+    + Cluster: patronidemo (7186662553319358497) ----+----+-----------+
+    | Member        | Host       | Role    | State   | TL | Lag in MB |
+    +---------------+------------+---------+---------+----+-----------+
+    | patronidemo-0 | 10.244.0.5 | Leader  | running |  1 |           |
+    | patronidemo-1 | 10.244.0.6 | Replica | running |  1 |         0 |
+    | patronidemo-2 | 10.244.0.7 | Replica | running |  1 |         0 |
+    +---------------+------------+---------+---------+----+-----------+
+
+# Citus on K8s
+The Citus cluster with the StatefulSets, one coordinator with three Pods and two workers with two pods each.
+
+Example session:
+
+    $ kind create cluster
+    Creating cluster "kind" ...
+     ✓ Ensuring node image (kindest/node:v1.25.3) 🖼
+     ✓ Preparing nodes 📦
+     ✓ Writing configuration 📜
+     ✓ Starting control-plane 🕹️
+     ✓ Installing CNI 🔌
+     ✓ Installing StorageClass 💾
+    Set kubectl context to "kind-kind"
+    You can now use your cluster with:
+
+    kubectl cluster-info --context kind-kind
+
+    Thanks for using kind! 😊
+
+    demo@localhost:~/git/patroni/kubernetes$ docker build -f Dockerfile.citus -t patroni-citus-k8s .
+    Sending build context to Docker daemon  138.8kB
+    Step 1/11 : FROM postgres:15
+    ...
+    Successfully built 8cd73e325028
+    Successfully tagged patroni-citus-k8s:latest
+
+    $ kind load docker-image patroni-citus-k8s
+    Image: "" with ID "sha256:8cd73e325028d7147672494965e53453f5540400928caac0305015eb2c7027c7" not yet present on node "kind-control-plane", loading...
+
+    $ kubectl apply -f citus_k8s.yaml
+    service/citusdemo-0-config created
+    service/citusdemo-1-config created
+    service/citusdemo-2-config created
+    statefulset.apps/citusdemo-0 created
+    statefulset.apps/citusdemo-1 created
+    statefulset.apps/citusdemo-2 created
+    endpoints/citusdemo-0 created
+    service/citusdemo-0 created
+    endpoints/citusdemo-1 created
+    service/citusdemo-1 created
+    endpoints/citusdemo-2 created
+    service/citusdemo-2 created
+    service/citusdemo-workers created
+    secret/citusdemo created
+    serviceaccount/citusdemo created
+    role.rbac.authorization.k8s.io/citusdemo created
+    rolebinding.rbac.authorization.k8s.io/citusdemo created
+    clusterrole.rbac.authorization.k8s.io/patroni-k8s-ep-access created
+    clusterrolebinding.rbac.authorization.k8s.io/patroni-k8s-ep-access created
+
+    $ kubectl get sts
+    NAME          READY   AGE
+    citusdemo-0   1/3     6s  # coodinator (group=0)
+    citusdemo-1   1/2     6s  # worker (group=1)
+    citusdemo-2   1/2     6s  # worker (group=2)
+
+    $ kubectl get pods -l cluster-name=citusdemo -L role
+    NAME            READY   STATUS    RESTARTS   AGE    ROLE
+    citusdemo-0-0   1/1     Running   0          105s   master
+    citusdemo-0-1   1/1     Running   0          101s   replica
+    citusdemo-0-2   1/1     Running   0          96s    replica
+    citusdemo-1-0   1/1     Running   0          105s   master
+    citusdemo-1-1   1/1     Running   0          101s   replica
+    citusdemo-2-0   1/1     Running   0          105s   master
+    citusdemo-2-1   1/1     Running   0          101s   replica
+
+    $ kubectl exec -ti citusdemo-0-0 -- bash
+    postgres@citusdemo-0-0:~$ patronictl list
+    + Citus cluster: citusdemo -----------+--------------+---------+----+-----------+
+    | Group | Member        | Host        | Role         | State   | TL | Lag in MB |
+    +-------+---------------+-------------+--------------+---------+----+-----------+
+    |     0 | citusdemo-0-0 | 10.244.0.10 | Leader       | running |  1 |           |
+    |     0 | citusdemo-0-1 | 10.244.0.12 | Replica      | running |  1 |         0 |
+    |     0 | citusdemo-0-2 | 10.244.0.14 | Sync Standby | running |  1 |         0 |
+    |     1 | citusdemo-1-0 | 10.244.0.8  | Leader       | running |  1 |           |
+    |     1 | citusdemo-1-1 | 10.244.0.11 | Sync Standby | running |  1 |         0 |
+    |     2 | citusdemo-2-0 | 10.244.0.9  | Leader       | running |  1 |           |
+    |     2 | citusdemo-2-1 | 10.244.0.13 | Sync Standby | running |  1 |         0 |
+    +-------+---------------+-------------+--------------+---------+----+-----------+
+
+    postgres@citusdemo-0-0:~$ psql citus
+    psql (15.1 (Debian 15.1-1.pgdg110+1))
+    Type "help" for help.
+
+    citus=# table pg_dist_node;
+     nodeid | groupid |  nodename   | nodeport | noderack | hasmetadata | isactive | noderole | nodecluster | metadatasynced | shouldhaveshards
+    --------+---------+-------------+----------+----------+-------------+----------+----------+-------------+----------------+------------------
+          1 |       0 | 10.244.0.10 |     5432 | default  | t           | t        | primary  | default     | t              | f
+          2 |       1 | 10.244.0.8  |     5432 | default  | t           | t        | primary  | default     | t              | t
+          3 |       2 | 10.244.0.9  |     5432 | default  | t           | t        | primary  | default     | t              | t
+    (3 rows)

kubernetes/citus_k8s.yaml

@@ -0,0 +1,590 @@
+# headless services to avoid deletion of citusdemo-*-config endpoints
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-0-config
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '0'
+spec:
+  clusterIP: None
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-1-config
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '1'
+spec:
+  clusterIP: None
+
+---
+
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-2-config
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '2'
+spec:
+  clusterIP: None
+
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: &cluster_name citusdemo-0
+  labels: &labels
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '0'
+    citus-type: coordinator
+spec:
+  replicas: 3
+  serviceName: *cluster_name
+  selector:
+    matchLabels:
+      <<: *labels
+  template:
+    metadata:
+      labels:
+        <<: *labels
+    spec:
+      serviceAccountName: citusdemo
+      containers:
+      - name: *cluster_name
+        image: patroni-citus-k8s  # docker build -f Dockerfile.citus -t patroni-citus-k8s .
+        imagePullPolicy: IfNotPresent
+        readinessProbe:
+          httpGet:
+            scheme: HTTP
+            path: /readiness
+            port: 8008
+          initialDelaySeconds: 3
+          periodSeconds: 10
+          timeoutSeconds: 5
+          successThreshold: 1
+          failureThreshold: 3
+        ports:
+        - containerPort: 8008
+          protocol: TCP
+        - containerPort: 5432
+          protocol: TCP
+        volumeMounts:
+        - mountPath: /home/postgres/pgdata
+          name: pgdata
+        env:
+        - name: PATRONI_KUBERNETES_POD_IP
+          valueFrom:
+            fieldRef:
+              fieldPath: status.podIP
+        - name: PATRONI_KUBERNETES_NAMESPACE
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.namespace
+        - name: PATRONI_KUBERNETES_BYPASS_API_SERVICE
+          value: 'true'
+        - name: PATRONI_KUBERNETES_USE_ENDPOINTS
+          value: 'true'
+        - name: PATRONI_KUBERNETES_LABELS
+          value: '{application: patroni, cluster-name: citusdemo}'
+        - name: PATRONI_CITUS_DATABASE
+          value: citus
+        - name: PATRONI_CITUS_GROUP
+          value: '0'
+        - name: PATRONI_SUPERUSER_USERNAME
+          value: postgres
+        - name: PATRONI_SUPERUSER_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: citusdemo
+              key: superuser-password
+        - name: PATRONI_REPLICATION_USERNAME
+          value: standby
+        - name: PATRONI_REPLICATION_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: citusdemo
+              key: replication-password
+        - name: PATRONI_SCOPE
+          value: citusdemo
+        - name: PATRONI_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+        - name: PATRONI_POSTGRESQL_DATA_DIR
+          value: /home/postgres/pgdata/pgroot/data
+        - name: PATRONI_POSTGRESQL_PGPASS
+          value: /tmp/pgpass
+        - name: PATRONI_POSTGRESQL_LISTEN
+          value: '0.0.0.0:5432'
+        - name: PATRONI_RESTAPI_LISTEN
+          value: '0.0.0.0:8008'
+      terminationGracePeriodSeconds: 0
+      volumes:
+      - name: pgdata
+        emptyDir: {}
+#  volumeClaimTemplates:
+#  - metadata:
+#      labels:
+#        application: spilo
+#        spilo-cluster: *cluster_name
+#      annotations:
+#        volume.alpha.kubernetes.io/storage-class: anything
+#      name: pgdata
+#    spec:
+#      accessModes:
+#      - ReadWriteOnce
+#      resources:
+#        requests:
+#          storage: 5Gi
+
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: &cluster_name citusdemo-1
+  labels: &labels
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '1'
+    citus-type: worker
+spec:
+  replicas: 2
+  serviceName: *cluster_name
+  selector:
+    matchLabels:
+      <<: *labels
+  template:
+    metadata:
+      labels:
+        <<: *labels
+    spec:
+      serviceAccountName: citusdemo
+      containers:
+      - name: *cluster_name
+        image: patroni-citus-k8s  # docker build -f Dockerfile.citus -t patroni-citus-k8s .
+        imagePullPolicy: IfNotPresent
+        readinessProbe:
+          httpGet:
+            scheme: HTTP
+            path: /readiness
+            port: 8008
+          initialDelaySeconds: 3
+          periodSeconds: 10
+          timeoutSeconds: 5
+          successThreshold: 1
+          failureThreshold: 3
+        ports:
+        - containerPort: 8008
+          protocol: TCP
+        - containerPort: 5432
+          protocol: TCP
+        volumeMounts:
+        - mountPath: /home/postgres/pgdata
+          name: pgdata
+        env:
+        - name: PATRONI_KUBERNETES_POD_IP
+          valueFrom:
+            fieldRef:
+              fieldPath: status.podIP
+        - name: PATRONI_KUBERNETES_NAMESPACE
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.namespace
+        - name: PATRONI_KUBERNETES_BYPASS_API_SERVICE
+          value: 'true'
+        - name: PATRONI_KUBERNETES_USE_ENDPOINTS
+          value: 'true'
+        - name: PATRONI_KUBERNETES_LABELS
+          value: '{application: patroni, cluster-name: citusdemo}'
+        - name: PATRONI_CITUS_DATABASE
+          value: citus
+        - name: PATRONI_CITUS_GROUP
+          value: '1'
+        - name: PATRONI_SUPERUSER_USERNAME
+          value: postgres
+        - name: PATRONI_SUPERUSER_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: citusdemo
+              key: superuser-password
+        - name: PATRONI_REPLICATION_USERNAME
+          value: standby
+        - name: PATRONI_REPLICATION_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: citusdemo
+              key: replication-password
+        - name: PATRONI_SCOPE
+          value: citusdemo
+        - name: PATRONI_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+        - name: PATRONI_POSTGRESQL_DATA_DIR
+          value: /home/postgres/pgdata/pgroot/data
+        - name: PATRONI_POSTGRESQL_PGPASS
+          value: /tmp/pgpass
+        - name: PATRONI_POSTGRESQL_LISTEN
+          value: '0.0.0.0:5432'
+        - name: PATRONI_RESTAPI_LISTEN
+          value: '0.0.0.0:8008'
+      terminationGracePeriodSeconds: 0
+      volumes:
+      - name: pgdata
+        emptyDir: {}
+#  volumeClaimTemplates:
+#  - metadata:
+#      labels:
+#        application: spilo
+#        spilo-cluster: *cluster_name
+#      annotations:
+#        volume.alpha.kubernetes.io/storage-class: anything
+#      name: pgdata
+#    spec:
+#      accessModes:
+#      - ReadWriteOnce
+#      resources:
+#        requests:
+#          storage: 5Gi
+
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: &cluster_name citusdemo-2
+  labels: &labels
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '2'
+    citus-type: worker
+spec:
+  replicas: 2
+  serviceName: *cluster_name
+  selector:
+    matchLabels:
+      <<: *labels
+  template:
+    metadata:
+      labels:
+        <<: *labels
+    spec:
+      serviceAccountName: citusdemo
+      containers:
+      - name: *cluster_name
+        image: patroni-citus-k8s  # docker build -f Dockerfile.citus -t patroni-citus-k8s .
+        imagePullPolicy: IfNotPresent
+        readinessProbe:
+          httpGet:
+            scheme: HTTP
+            path: /readiness
+            port: 8008
+          initialDelaySeconds: 3
+          periodSeconds: 10
+          timeoutSeconds: 5
+          successThreshold: 1
+          failureThreshold: 3
+        ports:
+        - containerPort: 8008
+          protocol: TCP
+        - containerPort: 5432
+          protocol: TCP
+        volumeMounts:
+        - mountPath: /home/postgres/pgdata
+          name: pgdata
+        env:
+        - name: PATRONI_KUBERNETES_POD_IP
+          valueFrom:
+            fieldRef:
+              fieldPath: status.podIP
+        - name: PATRONI_KUBERNETES_NAMESPACE
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.namespace
+        - name: PATRONI_KUBERNETES_BYPASS_API_SERVICE
+          value: 'true'
+        - name: PATRONI_KUBERNETES_USE_ENDPOINTS
+          value: 'true'
+        - name: PATRONI_KUBERNETES_LABELS
+          value: '{application: patroni, cluster-name: citusdemo}'
+        - name: PATRONI_CITUS_DATABASE
+          value: citus
+        - name: PATRONI_CITUS_GROUP
+          value: '2'
+        - name: PATRONI_SUPERUSER_USERNAME
+          value: postgres
+        - name: PATRONI_SUPERUSER_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: citusdemo
+              key: superuser-password
+        - name: PATRONI_REPLICATION_USERNAME
+          value: standby
+        - name: PATRONI_REPLICATION_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: citusdemo
+              key: replication-password
+        - name: PATRONI_SCOPE
+          value: citusdemo
+        - name: PATRONI_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+        - name: PATRONI_POSTGRESQL_DATA_DIR
+          value: /home/postgres/pgdata/pgroot/data
+        - name: PATRONI_POSTGRESQL_PGPASS
+          value: /tmp/pgpass
+        - name: PATRONI_POSTGRESQL_LISTEN
+          value: '0.0.0.0:5432'
+        - name: PATRONI_RESTAPI_LISTEN
+          value: '0.0.0.0:8008'
+      terminationGracePeriodSeconds: 0
+      volumes:
+      - name: pgdata
+        emptyDir: {}
+#  volumeClaimTemplates:
+#  - metadata:
+#      labels:
+#        application: spilo
+#        spilo-cluster: *cluster_name
+#      annotations:
+#        volume.alpha.kubernetes.io/storage-class: anything
+#      name: pgdata
+#    spec:
+#      accessModes:
+#      - ReadWriteOnce
+#      resources:
+#        requests:
+#          storage: 5Gi
+          
+---
+apiVersion: v1
+kind: Endpoints
+metadata:
+  name: citusdemo-0
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '0'
+    citus-type: coordinator
+subsets: []
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-0
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '0'
+    citus-type: coordinator
+spec:
+  type: ClusterIP
+  ports:
+  - port: 5432
+    targetPort: 5432
+
+---
+apiVersion: v1
+kind: Endpoints
+metadata:
+  name: citusdemo-1
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '1'
+    citus-type: worker
+subsets: []
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-1
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '1'
+    citus-type: worker
+spec:
+  type: ClusterIP
+  ports:
+  - port: 5432
+    targetPort: 5432
+
+---
+apiVersion: v1
+kind: Endpoints
+metadata:
+  name: citusdemo-2
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '2'
+    citus-type: worker
+subsets: []
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-2
+  labels:
+    application: patroni
+    cluster-name: citusdemo
+    citus-group: '2'
+    citus-type: worker
+spec:
+  type: ClusterIP
+  ports:
+  - port: 5432
+    targetPort: 5432
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: citusdemo-workers
+  labels: &labels
+    application: patroni
+    cluster-name: citusdemo
+    citus-type: worker
+    role: master
+spec:
+  type: ClusterIP
+  selector:
+    <<: *labels
+  ports:
+  - port: 5432
+    targetPort: 5432
+
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: &cluster_name citusdemo
+  labels:
+    application: patroni
+    cluster-name: *cluster_name
+type: Opaque
+data:
+  superuser-password: emFsYW5kbw==
+  replication-password: cmVwLXBhc3M=
+
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: citusdemo
+
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: citusdemo
+rules:
+- apiGroups:
+  - ""
+  resources:
+  - configmaps
+  verbs:
+  - create
+  - get
+  - list
+  - patch
+  - update
+  - watch
+  # delete and deletecollection are required only for 'patronictl remove'
+  - delete
+  - deletecollection
+- apiGroups:
+  - ""
+  resources:
+  - endpoints
+  verbs:
+  - get
+  - patch
+  - update
+  # the following three privileges are necessary only when using endpoints
+  - create
+  - list
+  - watch
+  # delete and deletecollection are required only for for 'patronictl remove'
+  - delete
+  - deletecollection
+- apiGroups:
+  - ""
+  resources:
+  - pods
+  verbs:
+  - get
+  - list
+  - patch
+  - update
+  - watch
+# The following privilege is only necessary for creation of headless service
+# for citusdemo-config endpoint, in order to prevent cleaning it up by the
+# k8s master. You can avoid giving this privilege by explicitly creating the
+# service like it is done in this manifest (lines 2..10)
+- apiGroups:
+  - ""
+  resources:
+  - services
+  verbs:
+  - create
+
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: citusdemo
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: citusdemo
+subjects:
+- kind: ServiceAccount
+  name: citusdemo
+
+# Following privileges are only required if deployed not in the "default"
+# namespace and you want Patroni to bypass kubernetes service
+# (PATRONI_KUBERNETES_BYPASS_API_SERVICE=true)
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: patroni-k8s-ep-access
+rules:
+- apiGroups:
+  - ""
+  resources:
+  - endpoints
+  resourceNames:
+  - kubernetes
+  verbs:
+  - get
+
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: patroni-k8s-ep-access
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: patroni-k8s-ep-access
+subjects:
+- kind: ServiceAccount
+  name: citusdemo
+# The namespace must be specified explicitly.
+# If deploying to the different namespace you have to change it.
+  namespace: default

kubernetes/entrypoint.sh

@@ -12,15 +12,15 @@ bootstrap:
   dcs:
     postgresql:
       use_pg_rewind: true
+      pg_hba:
+      - host all all 0.0.0.0/0 md5
+      - host replication ${PATRONI_REPLICATION_USERNAME} ${PATRONI_KUBERNETES_POD_IP}/16 md5
   initdb:
   - auth-host: md5
   - auth-local: trust
   - encoding: UTF8
   - locale: en_US.UTF-8
   - data-checksums
-  pg_hba:
-  - host all all 0.0.0.0/0 md5
-  - host replication ${PATRONI_REPLICATION_USERNAME} ${PATRONI_KUBERNETES_POD_IP}/16 md5
 restapi:
   connect_address: '${PATRONI_KUBERNETES_POD_IP}:8008'
 postgresql:

kubernetes/openshift-example/README.md

@@ -1,5 +1,5 @@
 # Patroni OpenShift Configuration
-Patroni can be run in OpenShift. Based on the kubernetes configuration, the Dockerfile and Entrypoint has been modified to support the dynamic UID/GID configuration that is applied in OpenShift. This can be run under the standard `restricted` SCC. 
+Patroni can be run in OpenShift. Based on the kubernetes configuration, the Dockerfile and Entrypoint has been modified to support the dynamic UID/GID configuration that is applied in OpenShift. This can be run under the standard `restricted` SCC.
 
 # Examples
 
@@ -11,39 +11,39 @@ oc new-project patroni-test
 
 ## Build the image
 
-Note: Update the references when merged upstream. 
-Note: If deploying as a template for multiple users, the following commands should be performed in a shared namespace like `openshift`. 
+Note: Update the references when merged upstream.
+Note: If deploying as a template for multiple users, the following commands should be performed in a shared namespace like `openshift`.
 
 ```
 oc import-image postgres:10 --confirm -n openshift
 oc new-build https://github.com/zalando/patroni --context-dir=kubernetes -n openshift
 ```
 
-## Deploy the Image 
-Two configuration templates exist in [templates](templates) directory: 
-- Patroni Ephemeral
-- Patroni Persistent
+## Deploy the Image
+Two configuration templates exist in [templates](templates) directory:
+-   Patroni Ephemeral
+-   Patroni Persistent
 
-The only difference is whether or not the statefulset requests persistent storage. 
+The only difference is whether or not the statefulset requests persistent storage.
 
 ## Create the Template
-Install the template into the `openshift` namespace if this should be shared across projects: 
+Install the template into the `openshift` namespace if this should be shared across projects:
 
 ```
 oc create -f templates/template_patroni_ephemeral.yml -n openshift
 ```
 
-Then, from your own project: 
+Then, from your own project:
 
 ```
 oc new-app patroni-pgsql-ephemeral
 ```
 
-Once the pods are running, two configmaps should be available: 
+Once the pods are running, two configmaps should be available:
 
 ```
 $ oc get configmap
 NAME                DATA      AGE
 patroniocp-config   0         1m
 patroniocp-leader   0         1m
-```
+```

kubernetes/openshift-example/test/README.md

@@ -1,2 +1,2 @@
 # Jenkins Test
-This pipeline test will create a separate deployment config for a pgbench pod and execute a test against the patroni cluster. This is a sample and should be customized. 
+This pipeline test will create a separate deployment config for a pgbench pod and execute a test against the patroni cluster. This is a sample and should be customized.

mkbinary.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
 set -e
 
-pip install --ignore-installed setuptools==19.2 pyinstaller
-pyinstaller --clean --onefile patroni.spec
+pip install --ignore-installed pyinstaller
+pyinstaller --clean patroni.spec

patroni.spec

@@ -8,7 +8,7 @@ def hiddenimports():
     sys.path.insert(0, '.')
     try:
         import patroni.dcs
-        return patroni.dcs.dcs_modules()
+        return patroni.dcs.dcs_modules() + ['http.server']
     finally:
         sys.path.pop(0)
 
@@ -16,7 +16,10 @@ def hiddenimports():
 a = Analysis(['patroni/__main__.py'],
              pathex=[],
              binaries=None,
-             datas=None,
+             datas=[
+                ('patroni/postgresql/available_parameters/*.yml', 'patroni/postgresql/available_parameters'),
+                ('patroni/postgresql/available_parameters/*.yaml', 'patroni/postgresql/available_parameters'),
+            ],
              hiddenimports=hiddenimports(),
              hookspath=[],
              runtime_hooks=[],

patroni/__init__.py

@@ -1,41 +1,48 @@
-import sys
+"""Define general variables and functions for :mod:`patroni`.
+
+:var PATRONI_ENV_PREFIX: prefix for Patroni related configuration environment variables.
+:var KUBERNETES_ENV_PREFIX: prefix for Kubernetes related configuration environment variables.
+:var MIN_PSYCOPG2: minimum version of :mod:`psycopg2` required by Patroni to work.
+:var MIN_PSYCOPG3: minimum version of :mod:`psycopg` required by Patroni to work.
+"""
+from typing import Iterator, Tuple
 
 PATRONI_ENV_PREFIX = 'PATRONI_'
 KUBERNETES_ENV_PREFIX = 'KUBERNETES_'
 MIN_PSYCOPG2 = (2, 5, 4)
+MIN_PSYCOPG3 = (3, 0, 0)
 
 
-def fatal(string, *args):
-    sys.stderr.write('FATAL: ' + string.format(*args) + '\n')
-    sys.exit(1)
+def parse_version(version: str) -> Tuple[int, ...]:
+    """Convert *version* from human-readable format to tuple of integers.
 
+    .. note::
+        Designed for easy comparison of software versions in Python.
 
-def parse_version(version):
-    def _parse_version(version):
+    :param version: human-readable software version, e.g. ``2.5.4.dev1 (dt dec pq3 ext lo64)``.
+
+    :returns: tuple of *version* parts, each part as an integer.
+
+    :Example:
+
+        >>> parse_version('2.5.4.dev1 (dt dec pq3 ext lo64)')
+        (2, 5, 4)
+    """
+    def _parse_version(version: str) -> Iterator[int]:
+        """Yield each part of a human-readable version string as an integer.
+
+        :param version: human-readable software version, e.g. ``2.5.4.dev1``.
+
+        :yields: each part of *version* as an integer.
+
+        :Example:
+
+            >>> tuple(_parse_version('2.5.4.dev1'))
+            (2, 5, 4)
+        """
         for e in version.split('.'):
             try:
                 yield int(e)
             except ValueError:
                 break
     return tuple(_parse_version(version.split(' ')[0]))
-
-
-# We pass MIN_PSYCOPG2 and parse_version as arguments to simplify usage of check_psycopg from the setup.py
-def check_psycopg(_min_psycopg2=MIN_PSYCOPG2, _parse_version=parse_version):
-    min_psycopg2_str = '.'.join(map(str, _min_psycopg2))
-
-    try:
-        from psycopg2 import __version__
-        if _parse_version(__version__) >= _min_psycopg2:
-            return
-        version_str = __version__.split(' ')[0]
-    except ImportError:
-        version_str = None
-
-    try:
-        from psycopg import __version__
-    except ImportError:
-        error = 'Patroni requires psycopg2>={0}, psycopg2-binary, or psycopg>=3.0'.format(min_psycopg2_str)
-        if version_str:
-            error += ', but only psycopg2=={0} is available'.format(version_str)
-        fatal(error)

patroni/__main__.py

@@ -1,41 +1,93 @@
+"""Patroni main entry point.
+
+Implement ``patroni`` main daemon and expose its entry point.
+"""
+
 import logging
 import os
 import signal
+import sys
 import time
 
-from .daemon import AbstractPatroniDaemon, abstract_main
+from argparse import Namespace
+from typing import Any, Dict, List, Optional, TYPE_CHECKING
+
+from patroni import MIN_PSYCOPG2, MIN_PSYCOPG3, parse_version
+from patroni.daemon import AbstractPatroniDaemon, abstract_main, get_base_arg_parser
+from patroni.tags import Tags
+
+if TYPE_CHECKING:  # pragma: no cover
+    from .config import Config
 
 logger = logging.getLogger(__name__)
 
 
-class Patroni(AbstractPatroniDaemon):
+class Patroni(AbstractPatroniDaemon, Tags):
+    """Implement ``patroni`` command daemon.
 
-    def __init__(self, config):
-        from .api import RestApiServer
-        from .dcs import get_dcs
-        from .ha import Ha
-        from .postgresql import Postgresql
-        from .request import PatroniRequest
-        from .version import __version__
-        from .watchdog import Watchdog
+    :ivar version: Patroni version.
+    :ivar dcs: DCS object.
+    :ivar watchdog: watchdog handler, if configured to use watchdog.
+    :ivar postgresql: managed Postgres instance.
+    :ivar api: REST API server instance of this node.
+    :ivar request: wrapper for performing HTTP requests.
+    :ivar ha: HA handler.
+    :ivar next_run: time when to run the next HA loop cycle.
+    :ivar scheduled_restart: when a restart has been scheduled to occur, if any. In that case, should contain two keys:
+        * ``schedule``: timestamp when restart should occur;
+        * ``postmaster_start_time``: timestamp when Postgres was last started.
+    """
+
+    def __init__(self, config: 'Config') -> None:
+        """Create a :class:`Patroni` instance with the given *config*.
+
+        Get a connection to the DCS, configure watchdog (if required), set up Patroni interface with Postgres, configure
+        the HA loop and bring the REST API up.
+
+        .. note::
+            Expected to be instantiated and run through :func:`~patroni.daemon.abstract_main`.
+
+        :param config: Patroni configuration.
+        """
+        from patroni.api import RestApiServer
+        from patroni.dcs import get_dcs
+        from patroni.ha import Ha
+        from patroni.postgresql import Postgresql
+        from patroni.request import PatroniRequest
+        from patroni.version import __version__
+        from patroni.watchdog import Watchdog
 
         super(Patroni, self).__init__(config)
 
         self.version = __version__
         self.dcs = get_dcs(self.config)
+        self.request = PatroniRequest(self.config, True)
+
+        self.ensure_unique_name()
+
         self.watchdog = Watchdog(self.config)
         self.load_dynamic_configuration()
 
-        self.postgresql = Postgresql(self.config['postgresql'])
+        self.postgresql = Postgresql(self.config['postgresql'], self.dcs.mpp)
         self.api = RestApiServer(self, self.config['restapi'])
-        self.request = PatroniRequest(self.config, True)
         self.ha = Ha(self)
 
-        self.tags = self.get_tags()
+        self._tags = self._get_tags()
         self.next_run = time.time()
-        self.scheduled_restart = {}
+        self.scheduled_restart: Dict[str, Any] = {}
 
-    def load_dynamic_configuration(self):
+    def load_dynamic_configuration(self) -> None:
+        """Load Patroni dynamic configuration.
+
+        Load dynamic configuration from the DCS, if `/config` key is available in the DCS, otherwise fall back to
+        ``bootstrap.dcs`` section from the configuration file.
+
+        If the DCS connection fails returning the exception :class:`~patroni.exceptions.DCSError` an attempt will be
+        remade every 5 seconds.
+
+        .. note::
+            This method is called only once, at the time when Patroni is started.
+        """
         from patroni.exceptions import DCSError
         while True:
             try:
@@ -47,28 +99,57 @@ class Patroni(AbstractPatroniDaemon):
                 elif not self.config.dynamic_configuration and 'bootstrap' in self.config:
                     if self.config.set_dynamic_configuration(self.config['bootstrap']['dcs']):
                         self.dcs.reload_config(self.config)
+                        self.watchdog.reload_config(self.config)
                 break
             except DCSError:
                 logger.warning('Can not get cluster from dcs')
                 time.sleep(5)
 
-    def get_tags(self):
-        return {tag: value for tag, value in self.config.get('tags', {}).items()
-                if tag not in ('clonefrom', 'nofailover', 'noloadbalance', 'nosync') or value}
+    def ensure_unique_name(self) -> None:
+        """A helper method to prevent splitbrain from operator naming error."""
+        from patroni.dcs import Member
 
-    @property
-    def nofailover(self):
-        return bool(self.tags.get('nofailover', False))
+        cluster = self.dcs.get_cluster()
+        if not cluster:
+            return
+        member = cluster.get_member(self.config['name'], False)
+        if not isinstance(member, Member):
+            return
+        try:
+            # Silence annoying WARNING: Retrying (...) messages when Patroni is quickly restarted.
+            # At this moment we don't have custom log levels configured and hence shouldn't lose anything useful.
+            self.logger.update_loggers({'urllib3.connectionpool': 'ERROR'})
+            _ = self.request(member, endpoint="/liveness", timeout=3)
+            logger.fatal("Can't start; there is already a node named '%s' running", self.config['name'])
+            sys.exit(1)
+        except Exception:
+            self.logger.update_loggers({})
 
-    @property
-    def nosync(self):
-        return bool(self.tags.get('nosync', False))
+    def _get_tags(self) -> Dict[str, Any]:
+        """Get tags configured for this node, if any.
 
-    def reload_config(self, sighup=False, local=False):
+        :returns: a dictionary of tags set for this node.
+        """
+        return self._filter_tags(self.config.get('tags', {}))
+
+    def reload_config(self, sighup: bool = False, local: Optional[bool] = False) -> None:
+        """Apply new configuration values for ``patroni`` daemon.
+
+        Reload:
+            * Cached tags;
+            * Request wrapper configuration;
+            * REST API configuration;
+            * Watchdog configuration;
+            * Postgres configuration;
+            * DCS configuration.
+
+        :param sighup: if it is related to a SIGHUP signal.
+        :param local: if there has been changes to the local configuration file.
+        """
         try:
             super(Patroni, self).reload_config(sighup, local)
             if local:
-                self.tags = self.get_tags()
+                self._tags = self._get_tags()
                 self.request.reload_config(self.config)
             if local or sighup and self.api.reload_local_certificate():
                 self.api.reload_config(self.config['restapi'])
@@ -79,14 +160,16 @@ class Patroni(AbstractPatroniDaemon):
             logger.exception('Failed to reload config_file=%s', self.config.config_file)
 
     @property
-    def replicatefrom(self):
-        return self.tags.get('replicatefrom')
+    def tags(self) -> Dict[str, Any]:
+        """Tags configured for this node, if any."""
+        return self._tags
 
-    @property
-    def noloadbalance(self):
-        return bool(self.tags.get('noloadbalance', False))
+    def schedule_next_run(self) -> None:
+        """Schedule the next run of the ``patroni`` daemon main loop.
 
-    def schedule_next_run(self):
+        Next run is scheduled based on previous run plus value of ``loop_wait`` configuration from DCS. If that has
+        already been exceeded, run the next cycle immediately.
+        """
         self.next_run += self.dcs.loop_wait
         current_time = time.time()
         nap_time = self.next_run - current_time
@@ -99,12 +182,22 @@ class Patroni(AbstractPatroniDaemon):
         elif self.ha.watch(nap_time):
             self.next_run = time.time()
 
-    def run(self):
+    def run(self) -> None:
+        """Run ``patroni`` daemon process main loop.
+
+        Start the REST API and keep running HA cycles every ``loop_wait`` seconds.
+        """
         self.api.start()
         self.next_run = time.time()
         super(Patroni, self).run()
 
-    def _run_cycle(self):
+    def _run_cycle(self) -> None:
+        """Run a cycle of the ``patroni`` daemon main loop.
+
+        Run an HA cycle and schedule the next cycle run. If any dynamic configuration change request is detected, apply
+        the change and cache the new dynamic configuration values in ``patroni.dynamic.json`` file under Postgres data
+        directory.
+        """
         logger.info(self.ha.run_cycle())
 
         if self.dcs.cluster and self.dcs.cluster.config and self.dcs.cluster.config.data \
@@ -116,7 +209,11 @@ class Patroni(AbstractPatroniDaemon):
 
         self.schedule_next_run()
 
-    def _shutdown(self):
+    def _shutdown(self) -> None:
+        """Perform shutdown of ``patroni`` daemon process.
+
+        Shut down the REST API and the HA handler.
+        """
         try:
             self.api.shutdown()
         except Exception:
@@ -127,27 +224,138 @@ class Patroni(AbstractPatroniDaemon):
             logger.exception('Exception during Ha.shutdown')
 
 
-def patroni_main():
+def patroni_main(configfile: str) -> None:
+    """Configure and start ``patroni`` main daemon process.
+
+    :param configfile: path to Patroni configuration file.
+    """
+    abstract_main(Patroni, configfile)
+
+
+def process_arguments() -> Namespace:
+    """Process command-line arguments.
+
+    Create a basic command-line parser through :func:`~patroni.daemon.get_base_arg_parser`, extend its capabilities by
+    adding these flags and parse command-line arguments.:
+
+      * ``--validate-config`` -- used to validate the Patroni configuration file
+      * ``--generate-config`` -- used to generate Patroni configuration from a running PostgreSQL instance
+      * ``--generate-sample-config`` -- used to generate a sample Patroni configuration
+
+    .. note::
+        If running with ``--generate-config``, ``--generate-sample-config`` or ``--validate-flag`` will exit
+        after generating or validating configuration.
+
+    :returns: parsed arguments, if not running with ``--validate-config`` flag.
+    """
+    from patroni.config_generator import generate_config
+
+    parser = get_base_arg_parser()
+    group = parser.add_mutually_exclusive_group()
+    group.add_argument('--validate-config', action='store_true', help='Run config validator and exit')
+    group.add_argument('--generate-sample-config', action='store_true',
+                       help='Generate a sample Patroni yaml configuration file')
+    group.add_argument('--generate-config', action='store_true',
+                       help='Generate a Patroni yaml configuration file for a running instance')
+    parser.add_argument('--dsn', help='Optional DSN string of the instance to be used as a source \
+                                    for config generation. Superuser connection is required.')
+    args = parser.parse_args()
+
+    if args.generate_sample_config:
+        generate_config(args.configfile, True, None)
+        sys.exit(0)
+    elif args.generate_config:
+        generate_config(args.configfile, False, args.dsn)
+        sys.exit(0)
+    elif args.validate_config:
+        from patroni.validator import schema
+        from patroni.config import Config, ConfigParseError
+
+        try:
+            Config(args.configfile, validator=schema)
+            sys.exit()
+        except ConfigParseError as e:
+            sys.exit(e.value)
+
+    return args
+
+
+def check_psycopg() -> None:
+    """Ensure at least one among :mod:`psycopg2` or :mod:`psycopg` libraries are available in the environment.
+
+    .. note::
+        Patroni chooses :mod:`psycopg2` over :mod:`psycopg`, if possible.
+
+        If nothing meeting the requirements is found, then exit with a fatal message.
+    """
+    min_psycopg2_str = '.'.join(map(str, MIN_PSYCOPG2))
+    min_psycopg3_str = '.'.join(map(str, MIN_PSYCOPG3))
+
+    available_versions: List[str] = []
+
+    # try psycopg2
+    try:
+        from psycopg2 import __version__
+        if parse_version(__version__) >= MIN_PSYCOPG2:
+            return
+        available_versions.append('psycopg2=={0}'.format(__version__.split(' ')[0]))
+    except ImportError:
+        logger.debug('psycopg2 module is not available')
+
+    # try psycopg3
+    try:
+        from psycopg import __version__
+        if parse_version(__version__) >= MIN_PSYCOPG3:
+            return
+        available_versions.append('psycopg=={0}'.format(__version__.split(' ')[0]))
+    except ImportError:
+        logger.debug('psycopg module is not available')
+
+    error = f'FATAL: Patroni requires psycopg2>={min_psycopg2_str}, psycopg2-binary, or psycopg>={min_psycopg3_str}'
+    if available_versions:
+        error += ', but only {0} {1} available'.format(
+            ' and '.join(available_versions),
+            'is' if len(available_versions) == 1 else 'are')
+    sys.exit(error)
+
+
+def main() -> None:
+    """Main entrypoint of :mod:`patroni.__main__`.
+
+    Process command-line arguments, ensure :mod:`psycopg2` (or :mod:`psycopg`) attendee the pre-requisites and start
+    ``patroni`` daemon process.
+
+    .. note::
+        If running through a Docker container, make the main process take care of init process duties and run
+        ``patroni`` daemon as another process. In that case relevant signals received by the main process and forwarded
+        to ``patroni`` daemon process.
+    """
     from multiprocessing import freeze_support
-    from patroni.validator import schema
 
+    # Executables created by PyInstaller are frozen, thus we need to enable frozen support for
+    # :mod:`multiprocessing` to avoid :class:`RuntimeError` exceptions.
     freeze_support()
-    abstract_main(Patroni, schema)
 
+    check_psycopg()
+
+    args = process_arguments()
 
-def main():
     if os.getpid() != 1:
-        from . import check_psycopg
-
-        check_psycopg()
-        return patroni_main()
+        return patroni_main(args.configfile)
 
     # Patroni started with PID=1, it looks like we are in the container
+    from types import FrameType
     pid = 0
 
     # Looks like we are in a docker, so we will act like init
-    def sigchld_handler(signo, stack_frame):
+    def sigchld_handler(signo: int, stack_frame: Optional[FrameType]) -> None:
+        """Handle ``SIGCHLD`` received by main process from ``patroni`` daemon when the daemon terminates.
+
+        :param signo: signal number.
+        :param stack_frame: current stack frame.
+        """
         try:
+            # log exit code of all children processes, and break loop when there is none left
             while True:
                 ret = os.waitpid(-1, os.WNOHANG)
                 if ret == (0, 0):
@@ -157,7 +365,12 @@ def main():
         except OSError:
             pass
 
-    def passtochild(signo, stack_frame):
+    def passtochild(signo: int, stack_frame: Optional[FrameType]) -> None:
+        """Forward a signal *signo* from main process to child process.
+
+        :param signo: signal number.
+        :param stack_frame: current stack frame.
+        """
         if pid:
             os.kill(pid, signo)
 
@@ -172,7 +385,7 @@ def main():
     signal.signal(signal.SIGTERM, passtochild)
 
     import multiprocessing
-    patroni = multiprocessing.Process(target=patroni_main)
+    patroni = multiprocessing.Process(target=patroni_main, args=(args.configfile,))
     patroni.start()
     pid = patroni.pid
     patroni.join()

patroni/async_executor.py

@@ -1,5 +1,11 @@
+"""Implement facilities for executing asynchronous tasks."""
 import logging
+
 from threading import Event, Lock, RLock, Thread
+from types import TracebackType
+from typing import Any, Callable, Optional, Tuple, Type
+
+from .postgresql.cancellable import CancellableSubprocess
 
 logger = logging.getLogger(__name__)
 
@@ -8,65 +14,110 @@ class CriticalTask(object):
     """Represents a critical task in a background process that we either need to cancel or get the result of.
 
     Fields of this object may be accessed only when holding a lock on it. To perform the critical task the background
-    thread must, while holding lock on this object, check `is_cancelled` flag, run the task and mark the task as
-    complete using `complete()`.
+    thread must, while holding lock on this object, check ``is_cancelled`` flag, run the task and mark the task as
+    complete using :func:`complete`.
 
     The main thread must hold async lock to prevent the task from completing, hold lock on critical task object,
-    call cancel. If the task has completed `cancel()` will return False and `result` field will contain the result of
-    the task. When cancel returns True it is guaranteed that the background task will notice the `is_cancelled` flag.
+    call :func:`cancel`. If the task has completed :func:`cancel` will return ``False`` and ``result`` field will
+    contain the result of the task. When :func:`cancel` returns ``True`` it is guaranteed that the background task will
+    notice the ``is_cancelled`` flag.
+
+    :ivar is_cancelled: if the critical task has been cancelled.
+    :ivar result: contains the result of the task, if it has already been completed.
     """
-    def __init__(self):
+
+    def __init__(self) -> None:
+        """Create a new instance of :class:`CriticalTask`.
+
+        Instantiate the lock and the task control attributes.
+        """
         self._lock = Lock()
         self.is_cancelled = False
         self.result = None
 
-    def reset(self):
+    def reset(self) -> None:
         """Must be called every time the background task is finished.
 
-        Must be called from async thread. Caller must hold lock on async executor when calling."""
+        .. note::
+            Must be called from async thread. Caller must hold lock on async executor when calling.
+        """
         self.is_cancelled = False
         self.result = None
 
-    def cancel(self):
-        """Tries to cancel the task, returns True if the task has already run.
+    def cancel(self) -> bool:
+        """Tries to cancel the task.
 
-        Caller must hold lock on async executor and the task when calling."""
+        .. note::
+            Caller must hold lock on async executor and the task when calling.
+
+        :returns: ``False`` if the task has already run, or ``True`` it has been cancelled.
+        """
         if self.result is not None:
             return False
         self.is_cancelled = True
         return True
 
-    def complete(self, result):
-        """Mark task as completed along with a result.
+    def complete(self, result: Any) -> None:
+        """Mark task as completed along with a *result*.
 
-        Must be called from async thread. Caller must hold lock on task when calling."""
+        .. note::
+            Must be called from async thread. Caller must hold lock on task when calling.
+        """
         self.result = result
 
-    def __enter__(self):
+    def __enter__(self) -> 'CriticalTask':
+        """Acquire the object lock when entering the context manager."""
         self._lock.acquire()
         return self
 
-    def __exit__(self, exc_type, exc_val, exc_tb):
+    def __exit__(self, exc_type: Optional[Type[BaseException]],
+                 exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]) -> None:
+        """Release the object lock when exiting the context manager."""
         self._lock.release()
 
 
 class AsyncExecutor(object):
+    """Asynchronous executor of (long) tasks.
 
-    def __init__(self, cancellable, ha_wakeup):
+    :ivar critical_task: a :class:`CriticalTask` instance to handle execution of critical background tasks.
+    """
+
+    def __init__(self, cancellable: CancellableSubprocess, ha_wakeup: Callable[..., None]) -> None:
+        """Create a new instance of :class:`AsyncExecutor`.
+
+        Configure the given *cancellable* and *ha_wakeup*, initializes the control attributes, and instantiate the lock
+        and event objects that are used to access attributes and manage communication between threads.
+
+        :param cancellable: a subprocess that supports being cancelled.
+        :param ha_wakeup: function to wake up the HA loop.
+        """
         self._cancellable = cancellable
         self._ha_wakeup = ha_wakeup
         self._thread_lock = RLock()
-        self._scheduled_action = None
+        self._scheduled_action: Optional[str] = None
         self._scheduled_action_lock = RLock()
         self._is_cancelled = False
         self._finish_event = Event()
         self.critical_task = CriticalTask()
 
     @property
-    def busy(self):
+    def busy(self) -> bool:
+        """``True`` if there is an action scheduled to occur, else ``False``."""
         return self.scheduled_action is not None
 
-    def schedule(self, action):
+    def schedule(self, action: str) -> Optional[str]:
+        """Schedule *action* to be executed.
+
+        .. note::
+            Must be called before executing a task.
+
+        .. note::
+            *action* can only be scheduled if there is no other action currently scheduled.
+
+        :param action: action to be executed.
+
+        :returns: ``None`` if *action* has been successfully scheduled, or the previously scheduled action, if any.
+        """
         with self._scheduled_action_lock:
             if self._scheduled_action is not None:
                 return self._scheduled_action
@@ -76,15 +127,33 @@ class AsyncExecutor(object):
         return None
 
     @property
-    def scheduled_action(self):
+    def scheduled_action(self) -> Optional[str]:
+        """The currently scheduled action, if any, else ``None``."""
         with self._scheduled_action_lock:
             return self._scheduled_action
 
-    def reset_scheduled_action(self):
+    def reset_scheduled_action(self) -> None:
+        """Unschedule a previously scheduled action, if any.
+
+        .. note::
+            Must be called once the scheduled task finishes or is cancelled.
+        """
         with self._scheduled_action_lock:
             self._scheduled_action = None
 
-    def run(self, func, args=()):
+    def run(self, func: Callable[..., Any], args: Tuple[Any, ...] = ()) -> Optional[Any]:
+        """Run *func* with *args*.
+
+        .. note::
+            Expected to be executed through a thread.
+
+        :param func: function to be run. If it returns anything other than ``None``, HA loop will be woken up at the end
+            of :func:`run` execution.
+        :param args: arguments to be passed to *func*.
+
+        :returns: ``None`` if *func* execution has been cancelled or faced any exception, otherwise the result of
+            *func*.
+        """
         wakeup = False
         try:
             with self:
@@ -107,16 +176,37 @@ class AsyncExecutor(object):
             if wakeup is not None:
                 self._ha_wakeup()
 
-    def run_async(self, func, args=()):
+    def run_async(self, func: Callable[..., Any], args: Tuple[Any, ...] = ()) -> None:
+        """Start an async thread that runs *func* with *args*.
+
+        :param func: function to be run. Will be passed through args to :class:`~threading.Thread` with a target of
+            :func:`run`.
+        :param args: arguments to be passed along to :class:`~threading.Thread` with *func*.
+
+        """
         Thread(target=self.run, args=(func, args)).start()
 
-    def try_run_async(self, action, func, args=()):
+    def try_run_async(self, action: str, func: Callable[..., Any], args: Tuple[Any, ...] = ()) -> Optional[str]:
+        """Try to run an async task, if none is currently being executed.
+
+        :param action: name of the task to be executed.
+        :param func: actual function that performs the task *action*.
+        :param args: arguments to be passed to *func*.
+
+        :returns: ``None`` if *func* was scheduled successfully, otherwise an error message informing of an already
+            ongoing task.
+        """
         prev = self.schedule(action)
         if prev is None:
             return self.run_async(func, args)
         return 'Failed to run {0}, {1} is already in progress'.format(action, prev)
 
-    def cancel(self):
+    def cancel(self) -> None:
+        """Request cancellation of a scheduled async task, if any.
+
+        .. note::
+            Wait until task is cancelled before returning control to caller.
+        """
         with self:
             with self._scheduled_action_lock:
                 if self._scheduled_action is None:
@@ -130,8 +220,16 @@ class AsyncExecutor(object):
         with self:
             self.reset_scheduled_action()
 
-    def __enter__(self):
+    def __enter__(self) -> 'AsyncExecutor':
+        """Acquire the thread lock when entering the context manager."""
         self._thread_lock.acquire()
+        return self
 
-    def __exit__(self, *args):
+    def __exit__(self, exc_type: Optional[Type[BaseException]],
+                 exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]) -> None:
+        """Release the thread lock when exiting the context manager.
+
+        .. note::
+            The arguments are not used, but we need them to match the expected method signature.
+        """
         self._thread_lock.release()

patroni/collections.py

@@ -0,0 +1,209 @@
+"""Patroni custom object types somewhat like :mod:`collections` module.
+
+Provides a case insensitive :class:`dict` and :class:`set` object types.
+"""
+from collections import OrderedDict
+from typing import Any, Collection, Dict, Iterator, KeysView, MutableMapping, MutableSet, Optional
+
+
+class CaseInsensitiveSet(MutableSet[str]):
+    """A case-insensitive :class:`set`-like object.
+
+    Implements all methods and operations of :class:`~typing.MutableSet`. All values are expected to be strings.
+    The structure remembers the case of the last value set, however, contains testing is case insensitive.
+    """
+
+    def __init__(self, values: Optional[Collection[str]] = None) -> None:
+        """Create a new instance of :class:`CaseInsensitiveSet` with the given *values*.
+
+        :param values: values to be added to the set.
+        """
+        self._values: Dict[str, str] = {}
+        for v in values or ():
+            self.add(v)
+
+    def __repr__(self) -> str:
+        """Get a string representation of the set.
+
+        Provide a helpful way of recreating the set.
+
+        :returns: representation of the set, showing its values.
+
+        :Example:
+
+            >>> repr(CaseInsensitiveSet(('1', 'test', 'Test', 'TESt', 'test2')))  # doctest: +ELLIPSIS
+            "<CaseInsensitiveSet('1', 'TESt', 'test2') at ..."
+        """
+        return '<{0}{1} at {2:x}>'.format(type(self).__name__, tuple(self._values.values()), id(self))
+
+    def __str__(self) -> str:
+        """Get set values for printing.
+
+        :returns: set of values in string format.
+
+        :Example:
+
+            >>> str(CaseInsensitiveSet(('1', 'test', 'Test', 'TESt', 'test2')))  # doctest: +SKIP
+            "{'TESt', 'test2', '1'}"
+        """
+        return str(set(self._values.values()))
+
+    def __contains__(self, value: str) -> bool:
+        """Check if set contains *value*.
+
+        The check is performed case-insensitively.
+
+        :param value: value to be checked.
+
+        :returns: ``True`` if *value* is already in the set, ``False`` otherwise.
+        """
+        return value.lower() in self._values
+
+    def __iter__(self) -> Iterator[str]:
+        """Iterate over the values in this set.
+
+        :yields: values from set.
+        """
+        return iter(self._values.values())
+
+    def __len__(self) -> int:
+        """Get the length of this set.
+
+        :returns: number of values in the set.
+
+        :Example:
+
+        >>> len(CaseInsensitiveSet(('1', 'test', 'Test', 'TESt', 'test2')))
+        3
+        """
+        return len(self._values)
+
+    def add(self, value: str) -> None:
+        """Add *value* to this set.
+
+        Search is performed case-insensitively. If *value* is already in the set, overwrite it with *value*, so we
+        "remember" the last case of *value*.
+
+        :param value: value to be added to the set.
+        """
+        self._values[value.lower()] = value
+
+    def discard(self, value: str) -> None:
+        """Remove *value* from this set.
+
+        Search is performed case-insensitively. If *value* is not present in the set, no exception is raised.
+
+        :param value: value to be removed from the set.
+        """
+        self._values.pop(value.lower(), None)
+
+    def issubset(self, other: 'CaseInsensitiveSet') -> bool:
+        """Check if this set is a subset of *other*.
+
+        :param other: another set to be compared with this set.
+        :returns: ``True`` if this set is a subset of *other*, else ``False``.
+        """
+        return self <= other
+
+
+class CaseInsensitiveDict(MutableMapping[str, Any]):
+    """A case-insensitive :class:`dict`-like object.
+
+    Implements all methods and operations of :class:`~typing.MutableMapping` as well as :class:`dict`'s
+    :func:`~dict.copy`. All keys are expected to be strings. The structure remembers the case of the last key to be set,
+    and :func:`iter`, :func:`dict.keys`, :func:`dict.items`, :func:`dict.iterkeys`, and :func:`dict.iteritems` will
+    contain case-sensitive keys. However, querying and contains testing is case insensitive.
+    """
+
+    def __init__(self, data: Optional[Dict[str, Any]] = None) -> None:
+        """Create a new instance of :class:`CaseInsensitiveDict` with the given *data*.
+
+        :param data: initial dictionary to create a :class:`CaseInsensitiveDict` from.
+        """
+        self._values: OrderedDict[str, Any] = OrderedDict()
+        self.update(data or {})
+
+    def __setitem__(self, key: str, value: Any) -> None:
+        """Assign *value* to *key* in this dict.
+
+        *key* is searched/stored case-insensitively in the dict. The corresponding value in the dict is a tuple of:
+            * original *key*;
+            * *value*.
+
+        :param key: key to be created or updated in the dict.
+        :param value: value for *key*.
+        """
+        self._values[key.lower()] = (key, value)
+
+    def __getitem__(self, key: str) -> Any:
+        """Get the value corresponding to *key*.
+
+        *key* is searched case-insensitively in the dict.
+
+        .. note:
+            If *key* is not present in the dict, :class:`KeyError` will be triggered.
+
+        :param key: key to be searched in the dict.
+
+        :returns: value corresponding to *key*.
+        """
+        return self._values[key.lower()][1]
+
+    def __delitem__(self, key: str) -> None:
+        """Remove *key* from this dict.
+
+        *key* is searched case-insensitively in the dict.
+
+        .. note:
+            If *key* is not present in the dict, :class:`KeyError` will be triggered.
+
+        :param key: key to be removed from the dict.
+        """
+        del self._values[key.lower()]
+
+    def __iter__(self) -> Iterator[str]:
+        """Iterate over keys of this dict.
+
+        :yields: each key present in the dict. Yields each key with its last case that has been stored.
+        """
+        return iter(key for key, _ in self._values.values())
+
+    def __len__(self) -> int:
+        """Get the length of this dict.
+
+        :returns: number of keys in the dict.
+
+        :Example:
+
+        >>> len(CaseInsensitiveDict({'a': 'b', 'A': 'B', 'c': 'd'}))
+        2
+        """
+        return len(self._values)
+
+    def copy(self) -> 'CaseInsensitiveDict':
+        """Create a copy of this dict.
+
+        :return: a new dict object with the same keys and values of this dict.
+        """
+        return CaseInsensitiveDict({v[0]: v[1] for v in self._values.values()})
+
+    def keys(self) -> KeysView[str]:
+        """Return a new view of the dict's keys.
+
+        :returns: a set-like object providing a view on the dict's keys
+        """
+        return self._values.keys()
+
+    def __repr__(self) -> str:
+        """Get a string representation of the dict.
+
+        Provide a helpful way of recreating the dict.
+
+        :returns: representation of the dict, showing its keys and values.
+
+        :Example:
+
+            >>> repr(CaseInsensitiveDict({'a': 'b', 'A': 'B', 'c': 'd'}))  # doctest: +ELLIPSIS
+            "<CaseInsensitiveDict{'A': 'B', 'c': 'd'} at ..."
+        """
+        return '<{0}{1} at {2:x}>'.format(type(self).__name__, dict(self.items()), id(self))

patroni/config.py

@@ -1,3 +1,5 @@
+"""Facilities related to Patroni configuration."""
+import re
 import json
 import logging
 import os
@@ -7,11 +9,16 @@ import yaml
 
 from collections import defaultdict
 from copy import deepcopy
-from patroni import PATRONI_ENV_PREFIX
-from patroni.exceptions import ConfigParseError
-from patroni.dcs import ClusterConfig
-from patroni.postgresql.config import CaseInsensitiveDict, ConfigHandler
-from patroni.utils import deep_compare, parse_bool, parse_int, patch_config
+from typing import Any, Callable, Collection, Dict, List, Optional, Union, TYPE_CHECKING
+
+from . import PATRONI_ENV_PREFIX
+from .collections import CaseInsensitiveDict
+from .dcs import ClusterConfig
+from .exceptions import ConfigParseError
+from .file_perm import pg_perm
+from .postgresql.config import ConfigHandler
+from .validator import IntValidator
+from .utils import deep_compare, parse_bool, parse_int, patch_config
 
 logger = logging.getLogger(__name__)
 
@@ -30,44 +37,55 @@ _AUTH_ALLOWED_PARAMETERS = (
 )
 
 
-def default_validator(conf):
+def default_validator(conf: Dict[str, Any]) -> List[str]:
+    """Ensure *conf* is not empty.
+
+    Designed to be used as default validator for :class:`Config` objects, if no specific validator is provided.
+
+    :param conf: configuration to be validated.
+
+    :returns: an empty list -- :class:`Config` expects the validator to return a list of 0 or more issues found while
+        validating the configuration.
+
+    :raises:
+        :class:`ConfigParseError`: if *conf* is empty.
+    """
     if not conf:
         raise ConfigParseError("Config is empty.")
+    return []
 
 
 class Config(object):
-    """
+    """Handle Patroni configuration.
+
     This class is responsible for:
 
-      1) Building and giving access to `effective_configuration` from:
-         * `Config.__DEFAULT_CONFIG` -- some sane default values
-         * `dynamic_configuration` -- configuration stored in DCS
-         * `local_configuration` -- configuration from `config.yml` or environment
+      1) Building and giving access to ``effective_configuration`` from:
 
-      2) Saving and loading `dynamic_configuration` into 'patroni.dynamic.json' file
+         * ``Config.__DEFAULT_CONFIG`` -- some sane default values;
+         * ``dynamic_configuration`` -- configuration stored in DCS;
+         * ``local_configuration`` -- configuration from `config.yml` or environment.
+
+      2) Saving and loading ``dynamic_configuration`` into 'patroni.dynamic.json' file
          located in local_configuration['postgresql']['data_dir'] directory.
-         This is necessary to be able to restore `dynamic_configuration`
-         if DCS was accidentally wiped
+         This is necessary to be able to restore ``dynamic_configuration``
+         if DCS was accidentally wiped.
 
-      3) Loading of configuration file in the old format and converting it into new format
+      3) Loading of configuration file in the old format and converting it into new format.
 
-      4) Mimicking some of the `dict` interfaces to make it possible
-         to work with it as with the old `config` object.
+      4) Mimicking some ``dict`` interfaces to make it possible
+         to work with it as with the old ``config`` object.
+
+    :cvar PATRONI_CONFIG_VARIABLE: name of the environment variable that can be used to load Patroni configuration from.
+    :cvar __CACHE_FILENAME: name of the file used to cache dynamic configuration under Postgres data directory.
+    :cvar __DEFAULT_CONFIG: default configuration values for some Patroni settings.
     """
 
     PATRONI_CONFIG_VARIABLE = PATRONI_ENV_PREFIX + 'CONFIGURATION'
 
     __CACHE_FILENAME = 'patroni.dynamic.json'
-    __DEFAULT_CONFIG = {
+    __DEFAULT_CONFIG: Dict[str, Any] = {
         'ttl': 30, 'loop_wait': 10, 'retry_timeout': 10,
-        'maximum_lag_on_failover': 1048576,
-        'maximum_lag_on_syncnode': -1,
-        'check_timeline': False,
-        'master_start_timeout': 300,
-        'master_stop_timeout': 0,
-        'synchronous_mode': False,
-        'synchronous_mode_strict': False,
-        'synchronous_node_count': 1,
         'standby_cluster': {
             'create_replica_methods': '',
             'host': '',
@@ -78,29 +96,45 @@ class Config(object):
             'recovery_min_apply_delay': ''
         },
         'postgresql': {
-            'bin_dir': '',
             'use_slots': True,
             'parameters': CaseInsensitiveDict({p: v[0] for p, v in ConfigHandler.CMDLINE_OPTIONS.items()
-                                               if p not in ('wal_keep_segments', 'wal_keep_size')})
-        },
-        'watchdog': {
-            'mode': 'automatic',
+                                               if v[0] is not None and p not in ('wal_keep_segments', 'wal_keep_size')})
         }
     }
 
-    def __init__(self, configfile, validator=default_validator):
-        self._modify_index = -1
+    def __init__(self, configfile: str,
+                 validator: Optional[Callable[[Dict[str, Any]], List[str]]] = default_validator) -> None:
+        """Create a new instance of :class:`Config` and validate the loaded configuration using *validator*.
+
+        .. note::
+            Patroni will read configuration from these locations in this order:
+
+              * file or directory path passed as command-line argument (*configfile*), if it exists and the file or
+                files found in the directory can be parsed (see :meth:`~Config._load_config_path`), otherwise
+              * YAML file passed via the environment variable (see :attr:`PATRONI_CONFIG_VARIABLE`), if the referenced
+                file exists and can be parsed, otherwise
+              * from configuration values defined as environment variables, see
+                :meth:`~Config._build_environment_configuration`.
+
+        :param configfile: path to Patroni configuration file.
+        :param validator: function used to validate Patroni configuration. It should receive a dictionary which
+            represents Patroni configuration, and return a list of zero or more error messages based on validation.
+
+        :raises:
+            :class:`ConfigParseError`: if any issue is reported by *validator*.
+        """
+        self._modify_version = -1
         self._dynamic_configuration = {}
 
         self.__environment_configuration = self._build_environment_configuration()
 
-        # Patroni reads the configuration from the command-line argument if it exists, otherwise from the environment
-        self._config_file = configfile and os.path.exists(configfile) and configfile
+        self._config_file = configfile if configfile and os.path.exists(configfile) else None
         if self._config_file:
             self._local_configuration = self._load_config_file()
         else:
             config_env = os.environ.pop(self.PATRONI_CONFIG_VARIABLE, None)
             self._local_configuration = config_env and yaml.safe_load(config_env) or self.__environment_configuration
+
         if validator:
             errors = validator(self._local_configuration)
             if errors:
@@ -109,24 +143,49 @@ class Config(object):
         self.__effective_configuration = self._build_effective_configuration({}, self._local_configuration)
         self._data_dir = self.__effective_configuration.get('postgresql', {}).get('data_dir', "")
         self._cache_file = os.path.join(self._data_dir, self.__CACHE_FILENAME)
-        self._load_cache()
+        if validator:  # patronictl uses validator=None
+            self._load_cache()  # we don't want to load anything from local cache for ctl
+            self._validate_failover_tags()  # irrelevant for ctl
         self._cache_needs_saving = False
 
     @property
-    def config_file(self):
+    def config_file(self) -> Optional[str]:
+        """Path to Patroni configuration file, if any, else ``None``."""
         return self._config_file
 
     @property
-    def dynamic_configuration(self):
+    def dynamic_configuration(self) -> Dict[str, Any]:
+        """Deep copy of cached Patroni dynamic configuration."""
         return deepcopy(self._dynamic_configuration)
 
-    def check_mode(self, mode):
-        return bool(parse_bool(self._dynamic_configuration.get(mode)))
+    @property
+    def local_configuration(self) -> Dict[str, Any]:
+        """Deep copy of cached Patroni local configuration.
 
-    def _load_config_path(self, path):
+        :returns: copy of :attr:`~Config._local_configuration`
         """
-        If path is a file, loads the yml file pointed to by path.
-        If path is a directory, loads all yml files in that directory in alphabetical order
+        return deepcopy(dict(self._local_configuration))
+
+    @classmethod
+    def get_default_config(cls) -> Dict[str, Any]:
+        """Deep copy default configuration.
+
+        :returns: copy of :attr:`~Config.__DEFAULT_CONFIG`
+        """
+        return deepcopy(cls.__DEFAULT_CONFIG)
+
+    def _load_config_path(self, path: str) -> Dict[str, Any]:
+        """Load Patroni configuration file(s) from *path*.
+
+        If *path* is a file, load the yml file pointed to by *path*.
+        If *path* is a directory, load all yml files in that directory in alphabetical order.
+
+        :param path: path to either an YAML configuration file, or to a folder containing YAML configuration files.
+
+        :returns: configuration after reading the configuration file(s) from *path*.
+
+        :raises:
+            :class:`ConfigParseError`: if *path* is invalid.
         """
         if os.path.isfile(path):
             files = [path]
@@ -137,20 +196,26 @@ class Config(object):
             logger.error('config path %s is neither directory nor file', path)
             raise ConfigParseError('invalid config path')
 
-        overall_config = {}
+        overall_config: Dict[str, Any] = {}
         for fname in files:
             with open(fname) as f:
                 config = yaml.safe_load(f)
                 patch_config(overall_config, config)
         return overall_config
 
-    def _load_config_file(self):
-        """Loads config.yaml from filesystem and applies some values which were set via ENV"""
-        config = self._load_config_path(self._config_file)
+    def _load_config_file(self) -> Dict[str, Any]:
+        """Load configuration file(s) from filesystem and apply values which were set via environment variables.
+
+        :returns: final configuration after merging configuration file(s) and environment variables.
+        """
+        if TYPE_CHECKING:  # pragma: no cover
+            assert self.config_file is not None
+        config = self._load_config_path(self.config_file)
         patch_config(config, self.__environment_configuration)
         return config
 
-    def _load_cache(self):
+    def _load_cache(self) -> None:
+        """Load dynamic configuration from ``patroni.dynamic.json``."""
         if os.path.isfile(self._cache_file):
             try:
                 with open(self._cache_file) as f:
@@ -158,15 +223,23 @@ class Config(object):
             except Exception:
                 logger.exception('Exception when loading file: %s', self._cache_file)
 
-    def save_cache(self):
+    def save_cache(self) -> None:
+        """Save dynamic configuration to ``patroni.dynamic.json`` under Postgres data directory.
+
+        .. note::
+            ``patroni.dynamic.jsonXXXXXX`` is created as a temporary file and than renamed to ``patroni.dynamic.json``,
+            where ``XXXXXX`` is a random suffix.
+        """
         if self._cache_needs_saving:
             tmpfile = fd = None
             try:
+                pg_perm.set_permissions_from_data_directory(self._data_dir)
                 (fd, tmpfile) = tempfile.mkstemp(prefix=self.__CACHE_FILENAME, dir=self._data_dir)
                 with os.fdopen(fd, 'w') as f:
                     fd = None
                     json.dump(self.dynamic_configuration, f)
                 tmpfile = shutil.move(tmpfile, self._cache_file)
+                os.chmod(self._cache_file, pg_perm.file_create_mode)
                 self._cache_needs_saving = False
             except Exception:
                 logger.exception('Exception when saving file: %s', self._cache_file)
@@ -181,16 +254,84 @@ class Config(object):
                     except Exception:
                         logger.error('Can not remove temporary file %s', tmpfile)
 
+    def __get_and_maybe_adjust_int_value(self, config: Dict[str, Any], param: str, min_value: int) -> int:
+        """Get, validate and maybe adjust a *param* integer value from the *config* :class:`dict`.
+
+        .. note:
+            If the value is smaller than provided *min_value* we update the *config*.
+
+            This method may raise an exception if value isn't :class:`int` or cannot be casted to :class:`int`.
+
+        :param config: :class:`dict` object with new global configuration.
+        :param param: name of the configuration parameter we want to read/validate/adjust.
+        :param min_value: the minimum possible value that a given *param* could have.
+
+        :returns: an integer value which corresponds to a provided *param*.
+        """
+        value = int(config.get(param, self.__DEFAULT_CONFIG[param]))
+        if value < min_value:
+            logger.warning("%s=%d can't be smaller than %d, adjusting...", param, value, min_value)
+            value = config[param] = min_value
+        return value
+
+    def _validate_and_adjust_timeouts(self, config: Dict[str, Any]) -> None:
+        """Validate and adjust ``loop_wait``, ``retry_timeout``, and ``ttl`` values if necessary.
+
+        Minimum values:
+
+            * ``loop_wait``: 1 second;
+            * ``retry_timeout``: 3 seconds.
+            * ``ttl``: 20 seconds;
+
+        Maximum values:
+        In case if values don't fulfill the following rule, ``retry_timeout`` and ``loop_wait``
+        are reduced so that the rule is fulfilled:
+
+            .. code-block:: python
+
+                loop_wait + 2 * retry_timeout <= ttl
+
+        .. note:
+            We prefer to reduce ``loop_wait`` and will reduce ``retry_timeout`` only if ``loop_wait``
+            is already set to a minimal possible value.
+
+        :param config: :class:`dict` object with new global configuration.
+        """
+
+        min_loop_wait = 1
+        loop_wait = self. __get_and_maybe_adjust_int_value(config, 'loop_wait', min_loop_wait)
+        retry_timeout = self. __get_and_maybe_adjust_int_value(config, 'retry_timeout', 3)
+        ttl = self. __get_and_maybe_adjust_int_value(config, 'ttl', 20)
+
+        if min_loop_wait + 2 * retry_timeout > ttl:
+            config['loop_wait'] = min_loop_wait
+            config['retry_timeout'] = (ttl - min_loop_wait) // 2
+            logger.warning('Violated the rule "loop_wait + 2*retry_timeout <= ttl", where ttl=%d. '
+                           'Adjusting loop_wait from %d to %d and retry_timeout from %d to %d',
+                           ttl, loop_wait, min_loop_wait, retry_timeout, config['retry_timeout'])
+        elif loop_wait + 2 * retry_timeout > ttl:
+            config['loop_wait'] = ttl - 2 * retry_timeout
+            logger.warning('Violated the rule "loop_wait + 2*retry_timeout <= ttl", where ttl=%d and retry_timeout=%d.'
+                           ' Adjusting loop_wait from %d to %d', ttl, retry_timeout, loop_wait, config['loop_wait'])
+
     # configuration could be either ClusterConfig or dict
-    def set_dynamic_configuration(self, configuration):
+    def set_dynamic_configuration(self, configuration: Union[ClusterConfig, Dict[str, Any]]) -> bool:
+        """Set dynamic configuration values with given *configuration*.
+
+        :param configuration: new dynamic configuration values. Supports :class:`dict` for backward compatibility.
+
+        :returns: ``True`` if changes have been detected between current dynamic configuration and the new dynamic
+            *configuration*, ``False`` otherwise.
+        """
         if isinstance(configuration, ClusterConfig):
-            if self._modify_index == configuration.modify_index:
-                return False  # If the index didn't changed there is nothing to do
-            self._modify_index = configuration.modify_index
+            if self._modify_version == configuration.modify_version:
+                return False  # If the version didn't change there is nothing to do
+            self._modify_version = configuration.modify_version
             configuration = configuration.data
 
         if not deep_compare(self._dynamic_configuration, configuration):
             try:
+                self._validate_and_adjust_timeouts(configuration)
                 self.__effective_configuration = self._build_effective_configuration(configuration,
                                                                                      self._local_configuration)
                 self._dynamic_configuration = configuration
@@ -198,8 +339,17 @@ class Config(object):
                 return True
             except Exception:
                 logger.exception('Exception when setting dynamic_configuration')
+        return False
 
-    def reload_local_configuration(self):
+    def reload_local_configuration(self) -> Optional[bool]:
+        """Reload configuration values from the configuration file(s).
+
+        .. note::
+            Designed to be used when user applies changes to configuration file(s), so Patroni can use the new values
+            with a reload instead of a restart.
+
+        :returns: ``True`` if changes have been detected between current local configuration
+        """
         if self.config_file:
             try:
                 configuration = self._load_config_file()
@@ -207,6 +357,7 @@ class Config(object):
                     new_configuration = self._build_effective_configuration(self._dynamic_configuration, configuration)
                     self._local_configuration = configuration
                     self.__effective_configuration = new_configuration
+                    self._validate_failover_tags()
                     return True
                 else:
                     logger.info('No local configuration items changed.')
@@ -214,13 +365,83 @@ class Config(object):
                 logger.exception('Exception when reloading local configuration from %s', self.config_file)
 
     @staticmethod
-    def _process_postgresql_parameters(parameters, is_local=False):
-        return {name: value for name, value in (parameters or {}).items()
-                if name not in ConfigHandler.CMDLINE_OPTIONS or
-                not is_local and ConfigHandler.CMDLINE_OPTIONS[name][1](value)}
+    def _process_postgresql_parameters(parameters: Dict[str, Any], is_local: bool = False) -> Dict[str, Any]:
+        """Process Postgres *parameters*.
 
-    def _safe_copy_dynamic_configuration(self, dynamic_configuration):
-        config = deepcopy(self.__DEFAULT_CONFIG)
+        .. note::
+            If *is_local* configuration discard any setting from *parameters* that is listed under
+            :attr:`~patroni.postgresql.config.ConfigHandler.CMDLINE_OPTIONS` as those are supposed to be set only
+            through dynamic configuration.
+
+            When setting parameters from :attr:`~patroni.postgresql.config.ConfigHandler.CMDLINE_OPTIONS` through
+            dynamic configuration their value will be validated as per the validator defined in that very same
+            attribute entry. If the given value cannot be validated, a warning will be logged and the default value of
+            the GUC will be used instead.
+
+            Some parameters from :attr:`~patroni.postgresql.config.ConfigHandler.CMDLINE_OPTIONS` cannot be set even if
+            not *is_local* configuration:
+
+                * ``listen_addresses``: inferred from ``postgresql.listen`` local configuration or from
+                    ``PATRONI_POSTGRESQL_LISTEN`` environment variable;
+                * ``port``: inferred from ``postgresql.listen`` local configuration or from
+                    ``PATRONI_POSTGRESQL_LISTEN`` environment variable;
+                * ``cluster_name``: set through ``scope`` local configuration or through ``PATRONI_SCOPE`` environment
+                    variable;
+                * ``hot_standby``: always enabled;
+                * ``wal_log_hints``: always enabled.
+
+        :param parameters: Postgres parameters to be processed. Should be the parsed YAML value of
+            ``postgresql.parameters`` configuration, either from local or from dynamic configuration.
+
+        :param is_local: should be ``True`` if *parameters* refers to local configuration, or ``False`` if *parameters*
+            refers to dynamic configuration.
+
+        :returns: new value for ``postgresql.parameters`` after processing and validating *parameters*.
+        """
+        pg_params: Dict[str, Any] = {}
+
+        for name, value in (parameters or {}).items():
+            if name not in ConfigHandler.CMDLINE_OPTIONS:
+                pg_params[name] = value
+            elif not is_local:
+                validator = ConfigHandler.CMDLINE_OPTIONS[name][1]
+                if validator(value):
+                    int_val = parse_int(value) if isinstance(validator, IntValidator) else None
+                    pg_params[name] = int_val if isinstance(int_val, int) else value
+                else:
+                    logger.warning("postgresql parameter %s=%s failed validation, defaulting to %s",
+                                   name, value, ConfigHandler.CMDLINE_OPTIONS[name][0])
+
+        return pg_params
+
+    def _safe_copy_dynamic_configuration(self, dynamic_configuration: Dict[str, Any]) -> Dict[str, Any]:
+        """Create a copy of *dynamic_configuration*.
+
+        Merge *dynamic_configuration* with :attr:`__DEFAULT_CONFIG` (*dynamic_configuration* takes precedence), and
+        process ``postgresql.parameters`` from *dynamic_configuration* through :func:`_process_postgresql_parameters`,
+        if present.
+
+        .. note::
+            The following settings are not allowed in ``postgresql`` section as they are intended to be local
+            configuration, and are removed if present:
+
+                * ``connect_address``;
+                * ``proxy_address``;
+                * ``listen``;
+                * ``config_dir``;
+                * ``data_dir``;
+                * ``pgpass``;
+                * ``authentication``;
+
+            Besides that any setting present in *dynamic_configuration* but absent from :attr:`__DEFAULT_CONFIG` is
+            discarded.
+
+        :param dynamic_configuration: Patroni dynamic configuration.
+
+        :returns: copy of *dynamic_configuration*, merged with default dynamic configuration and with some sanity checks
+            performed over it.
+        """
+        config = self.get_default_config()
 
         for name, value in dynamic_configuration.items():
             if name == 'postgresql':
@@ -235,17 +456,30 @@ class Config(object):
                     if name in self.__DEFAULT_CONFIG['standby_cluster']:
                         config['standby_cluster'][name] = deepcopy(value)
             elif name in config:  # only variables present in __DEFAULT_CONFIG allowed to be overridden from DCS
-                if name in ('synchronous_mode', 'synchronous_mode_strict'):
-                    config[name] = value
-                else:
-                    config[name] = int(value)
+                config[name] = int(value)
         return config
 
     @staticmethod
-    def _build_environment_configuration():
-        ret = defaultdict(dict)
+    def _build_environment_configuration() -> Dict[str, Any]:
+        """Get local configuration settings that were specified through environment variables.
 
-        def _popenv(name):
+        :returns: dictionary containing the found environment variables and their values, respecting the expected
+            structure of Patroni configuration.
+        """
+        ret: Dict[str, Any] = defaultdict(dict)
+
+        def _popenv(name: str) -> Optional[str]:
+            """Get value of environment variable *name*.
+
+            .. note::
+                *name* is prefixed with :data:`~patroni.PATRONI_ENV_PREFIX` when searching in the environment.
+
+                Also, the corresponding environment variable is removed from the environment upon reading its value.
+
+            :param name: name of the environment variable.
+
+            :returns: value of *name*, if present in the environment, otherwise ``None``.
+            """
             return os.environ.pop(PATRONI_ENV_PREFIX + name.upper(), None)
 
         for param in ('name', 'namespace', 'scope'):
@@ -253,7 +487,24 @@ class Config(object):
             if value:
                 ret[param] = value
 
-        def _fix_log_env(name, oldname):
+        def _fix_log_env(name: str, oldname: str) -> None:
+            """Normalize a log related environment variable.
+
+            .. note::
+                Patroni used to support different names for log related environment variables in the past. As the
+                environment variables were renamed, this function takes care of mapping and normalizing the environment.
+
+                *name* is prefixed with :data:`~patroni.PATRONI_ENV_PREFIX` and ``LOG`` when searching in the
+                environment.
+
+                *oldname* is prefixed with :data:`~patroni.PATRONI_ENV_PREFIX` when searching in the environment.
+
+                If both *name* and *oldname* are set in the environment, *name* takes precedence.
+
+            :param name: new name of a log related environment variable.
+            :param oldname: original name of a log related environment variable.
+            :type oldname: str
+            """
             value = _popenv(oldname)
             name = PATRONI_ENV_PREFIX + 'LOG_' + name.upper()
             if value and name not in os.environ:
@@ -262,7 +513,16 @@ class Config(object):
         for name, oldname in (('level', 'loglevel'), ('format', 'logformat'), ('dateformat', 'log_datefmt')):
             _fix_log_env(name, oldname)
 
-        def _set_section_values(section, params):
+        def _set_section_values(section: str, params: List[str]) -> None:
+            """Get value of *params* environment variables that are related with *section*.
+
+            .. note::
+                The values are retrieved from the environment and updated directly into the returning dictionary of
+                :func:`_build_environment_configuration`.
+
+            :param section: configuration section the *params* belong to.
+            :param params: name of the Patroni settings.
+            """
             for param in params:
                 value = _popenv(section + '_' + param)
                 if value:
@@ -270,14 +530,21 @@ class Config(object):
 
         _set_section_values('restapi', ['listen', 'connect_address', 'certfile', 'keyfile', 'keyfile_password',
                                         'cafile', 'ciphers', 'verify_client', 'http_extra_headers',
-                                        'https_extra_headers', 'allowlist', 'allowlist_include_members'])
+                                        'https_extra_headers', 'allowlist', 'allowlist_include_members',
+                                        'request_queue_size'])
         _set_section_values('ctl', ['insecure', 'cacert', 'certfile', 'keyfile', 'keyfile_password'])
         _set_section_values('postgresql', ['listen', 'connect_address', 'proxy_address',
                                            'config_dir', 'data_dir', 'pgpass', 'bin_dir'])
-        _set_section_values('log', ['level', 'traceback_level', 'format', 'dateformat', 'max_queue_size',
-                                    'dir', 'file_size', 'file_num', 'loggers'])
+        _set_section_values('log', ['type', 'level', 'traceback_level', 'format', 'dateformat', 'static_fields',
+                                    'max_queue_size', 'dir', 'file_size', 'file_num', 'loggers'])
         _set_section_values('raft', ['data_dir', 'self_addr', 'partner_addrs', 'password', 'bind_addr'])
 
+        for binary in ('pg_ctl', 'initdb', 'pg_controldata', 'pg_basebackup', 'postgres', 'pg_isready', 'pg_rewind'):
+            value = _popenv('POSTGRESQL_BIN_' + binary)
+            if value:
+                ret['postgresql'].setdefault('bin_name', {})[binary] = value
+
+        # parse all values retrieved from the environment as Python objects, according to the expected type
         for first, second in (('restapi', 'allowlist_include_members'), ('ctl', 'insecure')):
             value = ret.get(first, {}).pop(second, None)
             if value:
@@ -285,14 +552,22 @@ class Config(object):
                 if value is not None:
                     ret[first][second] = value
 
-        for second in ('max_queue_size', 'file_size', 'file_num'):
-            value = ret.get('log', {}).pop(second, None)
-            if value:
-                value = parse_int(value)
-                if value is not None:
-                    ret['log'][second] = value
+        for first, params in (('restapi', ('request_queue_size',)),
+                              ('log', ('max_queue_size', 'file_size', 'file_num'))):
+            for second in params:
+                value = ret.get(first, {}).pop(second, None)
+                if value:
+                    value = parse_int(value)
+                    if value is not None:
+                        ret[first][second] = value
 
-        def _parse_list(value):
+        def _parse_list(value: str) -> Optional[List[str]]:
+            """Parse an YAML list *value* as a :class:`list`.
+
+            :param value: YAML list as a string.
+
+            :returns: *value* as :class:`list`.
+            """
             if not (value.strip().startswith('-') or '[' in value):
                 value = '[{0}]'.format(value)
             try:
@@ -308,7 +583,19 @@ class Config(object):
                 if value:
                     ret[first][second] = value
 
-        def _parse_dict(value):
+        logformat = ret.get('log', {}).get('format')
+        if logformat and not re.search(r'%\(\w+\)', logformat):
+            logformat = _parse_list(logformat)
+            if logformat:
+                ret['log']['format'] = logformat
+
+        def _parse_dict(value: str) -> Optional[Dict[str, Any]]:
+            """Parse an YAML dictionary *value* as a :class:`dict`.
+
+            :param value: YAML dictionary as a string.
+
+            :returns: *value* as :class:`dict`.
+            """
             if not value.strip().startswith('{'):
                 value = '{{{0}}}'.format(value)
             try:
@@ -317,7 +604,12 @@ class Config(object):
                 logger.exception('Exception when parsing dict %s', value)
                 return None
 
-        for first, params in (('restapi', ('http_extra_headers', 'https_extra_headers')), ('log', ('loggers',))):
+        dict_configs = (
+            ('restapi', ('http_extra_headers', 'https_extra_headers')),
+            ('log', ('static_fields', 'loggers'))
+        )
+
+        for first, params in dict_configs:
             for second in params:
                 value = ret.get(first, {}).pop(second, None)
                 if value:
@@ -325,17 +617,25 @@ class Config(object):
                     if value:
                         ret[first][second] = value
 
-        def _get_auth(name, params=None):
-            ret = {}
-            for param in params or _AUTH_ALLOWED_PARAMETERS[:2]:
+        def _get_auth(name: str, params: Collection[str] = _AUTH_ALLOWED_PARAMETERS[:2]) -> Dict[str, str]:
+            """Get authorization related environment variables *params* from section *name*.
+
+            :param name: name of a configuration section that may contain authorization *params*.
+            :param params: the authorization settings that may be set under section *name*.
+
+            :returns: dictionary containing environment values for authorization *params* of section *name*.
+            """
+            ret: Dict[str, str] = {}
+            for param in params:
                 value = _popenv(name + '_' + param)
                 if value:
                     ret[param] = value
             return ret
 
-        restapi_auth = _get_auth('restapi')
-        if restapi_auth:
-            ret['restapi']['authentication'] = restapi_auth
+        for section in ('ctl', 'restapi'):
+            auth = _get_auth(section)
+            if auth:
+                ret[section]['authentication'] = auth
 
         authentication = {}
         for user_type in ('replication', 'superuser', 'rewind'):
@@ -349,22 +649,29 @@ class Config(object):
         for param in list(os.environ.keys()):
             if param.startswith(PATRONI_ENV_PREFIX):
                 # PATRONI_(ETCD|CONSUL|ZOOKEEPER|EXHIBITOR|...)_(HOSTS?|PORT|..)
-                name, suffix = (param[8:].split('_', 1) + [''])[:2]
+                name, suffix = (param[len(PATRONI_ENV_PREFIX):].split('_', 1) + [''])[:2]
                 if suffix in ('HOST', 'HOSTS', 'PORT', 'USE_PROXIES', 'PROTOCOL', 'SRV', 'SRV_SUFFIX', 'URL', 'PROXY',
                               'CACERT', 'CERT', 'KEY', 'VERIFY', 'TOKEN', 'CHECKS', 'DC', 'CONSISTENCY',
                               'REGISTER_SERVICE', 'SERVICE_CHECK_INTERVAL', 'SERVICE_CHECK_TLS_SERVER_NAME',
-                              'NAMESPACE', 'CONTEXT', 'USE_ENDPOINTS', 'SCOPE_LABEL', 'ROLE_LABEL', 'POD_IP',
-                              'PORTS', 'LABELS', 'BYPASS_API_SERVICE', 'KEY_PASSWORD', 'USE_SSL', 'SET_ACLS') and name:
+                              'SERVICE_TAGS', 'NAMESPACE', 'CONTEXT', 'USE_ENDPOINTS', 'SCOPE_LABEL', 'ROLE_LABEL',
+                              'POD_IP', 'PORTS', 'LABELS', 'BYPASS_API_SERVICE', 'RETRIABLE_HTTP_CODES', 'KEY_PASSWORD',
+                              'USE_SSL', 'SET_ACLS', 'GROUP', 'DATABASE', 'LEADER_LABEL_VALUE', 'FOLLOWER_LABEL_VALUE',
+                              'STANDBY_LEADER_LABEL_VALUE', 'TMP_ROLE_LABEL', 'AUTH_DATA') and name:
                     value = os.environ.pop(param)
-                    if suffix == 'PORT':
+                    if name == 'CITUS':
+                        if suffix == 'GROUP':
+                            value = parse_int(value)
+                        elif suffix != 'DATABASE':
+                            continue
+                    elif suffix == 'PORT':
                         value = value and parse_int(value)
-                    elif suffix in ('HOSTS', 'PORTS', 'CHECKS'):
+                    elif suffix in ('HOSTS', 'PORTS', 'CHECKS', 'SERVICE_TAGS', 'RETRIABLE_HTTP_CODES'):
                         value = value and _parse_list(value)
-                    elif suffix in ('LABELS', 'SET_ACLS'):
+                    elif suffix in ('LABELS', 'SET_ACLS', 'AUTH_DATA'):
                         value = _parse_dict(value)
                     elif suffix in ('USE_PROXIES', 'REGISTER_SERVICE', 'USE_ENDPOINTS', 'BYPASS_API_SERVICE', 'VERIFY'):
                         value = parse_bool(value)
-                    if value:
+                    if value is not None:
                         ret[name.lower()][suffix.lower()] = value
         for dcs in ('etcd', 'etcd3'):
             if dcs in ret:
@@ -373,14 +680,14 @@ class Config(object):
         users = {}
         for param in list(os.environ.keys()):
             if param.startswith(PATRONI_ENV_PREFIX):
-                name, suffix = (param[8:].rsplit('_', 1) + [''])[:2]
+                name, suffix = (param[len(PATRONI_ENV_PREFIX):].rsplit('_', 1) + [''])[:2]
                 # PATRONI_<username>_PASSWORD=<password>, PATRONI_<username>_OPTIONS=<option1,option2,...>
                 # CREATE USER "<username>" WITH <OPTIONS> PASSWORD '<password>'
                 if name and suffix == 'PASSWORD':
                     password = os.environ.pop(param)
                     if password:
                         users[name] = {'password': password}
-                        options = os.environ.pop(param[:-9] + '_OPTIONS', None)
+                        options = os.environ.pop(param[:-9] + '_OPTIONS', None)  # replace "_PASSWORD" with "_OPTIONS"
                         options = options and _parse_list(options)
                         if options:
                             users[name]['options'] = options
@@ -389,10 +696,25 @@ class Config(object):
 
         return ret
 
-    def _build_effective_configuration(self, dynamic_configuration, local_configuration):
+    def _build_effective_configuration(self, dynamic_configuration: Dict[str, Any],
+                                       local_configuration: Dict[str, Union[Dict[str, Any], Any]]) -> Dict[str, Any]:
+        """Build effective configuration by merging *dynamic_configuration* and *local_configuration*.
+
+        .. note::
+            *local_configuration* takes precedence over *dynamic_configuration* if a setting is defined in both.
+
+        :param dynamic_configuration: Patroni dynamic configuration.
+        :param local_configuration: Patroni local configuration.
+
+        :returns: _description_
+        """
         config = self._safe_copy_dynamic_configuration(dynamic_configuration)
         for name, value in local_configuration.items():
-            if name == 'postgresql':
+            if name == 'citus':  # remove invalid citus configuration
+                if isinstance(value, dict) and isinstance(value.get('group'), int)\
+                        and isinstance(value.get('database'), str):
+                    config[name] = value
+            elif name == 'postgresql':
                 for name, value in (value or {}).items():
                     if name == 'parameters':
                         config['postgresql'][name].update(self._process_postgresql_parameters(value, True))
@@ -401,9 +723,10 @@ class Config(object):
             elif name not in config or name in ['watchdog']:
                 config[name] = deepcopy(value) if value else {}
 
-        # restapi server expects to get restapi.auth = 'username:password'
-        if 'restapi' in config and 'authentication' in config['restapi']:
-            config['restapi']['auth'] = '{username}:{password}'.format(**config['restapi']['authentication'])
+        # restapi server expects to get restapi.auth = 'username:password' and similarly for `ctl`
+        for section in ('ctl', 'restapi'):
+            if section in config and 'authentication' in config[section]:
+                config[section]['auth'] = '{username}:{password}'.format(**config[section]['authentication'])
 
         # special treatment for old config
 
@@ -430,28 +753,86 @@ class Config(object):
         if 'name' not in config and 'name' in pg_config:
             config['name'] = pg_config['name']
 
+        # when bootstrapping the new Citus cluster (coordinator/worker) enable sync replication in global configuration
+        if 'citus' in config:
+            bootstrap = config.setdefault('bootstrap', {})
+            dcs = bootstrap.setdefault('dcs', {})
+            dcs.setdefault('synchronous_mode', True)
+
         updated_fields = (
             'name',
             'scope',
             'retry_timeout',
-            'synchronous_mode',
-            'synchronous_mode_strict',
-            'synchronous_node_count',
-            'maximum_lag_on_syncnode'
+            'citus'
         )
 
         pg_config.update({p: config[p] for p in updated_fields if p in config})
 
         return config
 
-    def get(self, key, default=None):
+    def get(self, key: str, default: Optional[Any] = None) -> Any:
+        """Get effective value of ``key`` setting from Patroni configuration root.
+
+        Designed to work the same way as :func:`dict.get`.
+
+        :param key: name of the setting.
+        :param default: default value if *key* is not present in the effective configuration.
+
+        :returns: value of *key*, if present in the effective configuration, otherwise *default*.
+        """
         return self.__effective_configuration.get(key, default)
 
-    def __contains__(self, key):
+    def __contains__(self, key: str) -> bool:
+        """Check if setting *key* is present in the effective configuration.
+
+        Designed to work the same way as :func:`dict.__contains__`.
+
+        :param key: name of the setting to be checked.
+
+        :returns: ``True`` if setting *key* exists in effective configuration, else ``False``.
+        """
         return key in self.__effective_configuration
 
-    def __getitem__(self, key):
+    def __getitem__(self, key: str) -> Any:
+        """Get value of setting *key* from effective configuration.
+
+        Designed to work the same way as :func:`dict.__getitem__`.
+
+        :param key: name of the setting.
+
+        :returns: value of setting *key*.
+
+        :raises:
+            :class:`KeyError`: if *key* is not present in effective configuration.
+        """
         return self.__effective_configuration[key]
 
-    def copy(self):
+    def copy(self) -> Dict[str, Any]:
+        """Get a deep copy of effective Patroni configuration.
+
+        :returns: a deep copy of the Patroni configuration.
+        """
         return deepcopy(self.__effective_configuration)
+
+    def _validate_failover_tags(self) -> None:
+        """Check ``nofailover``/``failover_priority`` config and warn user if it's contradictory.
+
+        .. note::
+          To preserve sanity (and backwards compatibility) the ``nofailover`` tag will still exist. A contradictory
+          configuration is one where ``nofailover`` is ``True`` but ``failover_priority > 0``, or where
+          ``nofailover`` is ``False``, but ``failover_priority <= 0``. Essentially, ``nofailover`` and
+          ``failover_priority`` are communicating different things.
+          This checks for this edge case (which is a misconfiguration on the part of the user) and warns them.
+          The behaviour is as if ``failover_priority`` were not provided (i.e ``nofailover`` is the
+          bedrock source of truth)
+        """
+        tags = self.get('tags', {})
+        if 'nofailover' not in tags:
+            return
+        nofailover_tag = tags.get('nofailover')
+        failover_priority_tag = parse_int(tags.get('failover_priority'))
+        if failover_priority_tag is not None \
+                and (bool(nofailover_tag) is True and failover_priority_tag > 0
+                     or bool(nofailover_tag) is False and failover_priority_tag <= 0):
+            logger.warning('Conflicting configuration between nofailover: %s and failover_priority: %s. '
+                           'Defaulting to nofailover: %s', nofailover_tag, failover_priority_tag, nofailover_tag)

patroni/config_generator.py

@@ -0,0 +1,511 @@
+"""patroni ``--generate-config`` machinery."""
+import abc
+import logging
+import os
+import psutil
+import socket
+import sys
+import yaml
+
+from getpass import getuser, getpass
+from contextlib import contextmanager
+from typing import Any, Dict, Iterator, List, Optional, TextIO, Tuple, TYPE_CHECKING, Union
+if TYPE_CHECKING:  # pragma: no cover
+    from psycopg import Cursor
+    from psycopg2 import cursor
+
+from . import psycopg
+from .config import Config
+from .exceptions import PatroniException
+from .log import PatroniLogger
+from .postgresql.config import ConfigHandler, parse_dsn
+from .postgresql.misc import postgres_major_version_to_int
+from .utils import get_major_version, parse_bool, patch_config, read_stripped
+
+
+# Mapping between the libpq connection parameters and the environment variables.
+# This dict should be kept in sync with `patroni.utils._AUTH_ALLOWED_PARAMETERS`
+# (we use "username" in the Patroni config for some reason, other parameter names are the same).
+_AUTH_ALLOWED_PARAMETERS_MAPPING = {
+    'user': 'PGUSER',
+    'password': 'PGPASSWORD',
+    'sslmode': 'PGSSLMODE',
+    'sslcert': 'PGSSLCERT',
+    'sslkey': 'PGSSLKEY',
+    'sslpassword': '',
+    'sslrootcert': 'PGSSLROOTCERT',
+    'sslcrl': 'PGSSLCRL',
+    'sslcrldir': 'PGSSLCRLDIR',
+    'gssencmode': 'PGGSSENCMODE',
+    'channel_binding': 'PGCHANNELBINDING'
+}
+NO_VALUE_MSG = '#FIXME'
+
+
+def get_address() -> Tuple[str, str]:
+    """Try to get hostname and the ip address for it returned by :func:`~socket.gethostname`.
+
+    .. note::
+        Can also return local ip.
+
+    :returns: tuple consisting of the hostname returned by :func:`~socket.gethostname`
+        and the first element in the sorted list of the addresses returned by :func:`~socket.getaddrinfo`.
+        Sorting guarantees it will prefer IPv4.
+        If an exception occured, hostname and ip values are equal to :data:`~patroni.config_generator.NO_VALUE_MSG`.
+    """
+    hostname = None
+    try:
+        hostname = socket.gethostname()
+        return hostname, sorted(socket.getaddrinfo(hostname, 0, socket.AF_UNSPEC, socket.SOCK_STREAM, 0),
+                                key=lambda x: x[0])[0][4][0]
+    except Exception as err:
+        logging.warning('Failed to obtain address: %r', err)
+        return NO_VALUE_MSG, NO_VALUE_MSG
+
+
+class AbstractConfigGenerator(abc.ABC):
+    """Object representing the generated Patroni config.
+
+    :ivar output_file: full path to the output file to be used.
+    :ivar pg_major: integer representation of the major PostgreSQL version.
+    :ivar config: dictionary used for the generated configuration storage.
+    """
+
+    _HOSTNAME, _IP = get_address()
+
+    def __init__(self, output_file: Optional[str]) -> None:
+        """Set up the output file (if passed), helper vars and the minimal config structure.
+
+        :param output_file: full path to the output file to be used.
+        """
+        self.output_file = output_file
+        self.pg_major = 0
+        self.config = self.get_template_config()
+
+        self.generate()
+
+    @classmethod
+    def get_template_config(cls) -> Dict[str, Any]:
+        """Generate a template config for further extension (e.g. in the inherited classes).
+
+        :returns: dictionary with the values gathered from Patroni env, hopefully defined hostname and ip address
+                  (otherwise set to :data:`~patroni.config_generator.NO_VALUE_MSG`), and some sane defaults.
+        """
+        template_config: Dict[str, Any] = {
+            'scope': NO_VALUE_MSG,
+            'name': cls._HOSTNAME,
+            'restapi': {
+                'connect_address': cls._IP + ':8008',
+                'listen': cls._IP + ':8008'
+            },
+            'log': {
+                'type': PatroniLogger.DEFAULT_TYPE,
+                'level': PatroniLogger.DEFAULT_LEVEL,
+                'traceback_level': PatroniLogger.DEFAULT_TRACEBACK_LEVEL,
+                'format': PatroniLogger.DEFAULT_FORMAT,
+                'max_queue_size': PatroniLogger.DEFAULT_MAX_QUEUE_SIZE
+            },
+            'postgresql': {
+                'data_dir': NO_VALUE_MSG,
+                'connect_address': cls._IP + ':5432',
+                'listen': cls._IP + ':5432',
+                'bin_dir': '',
+                'authentication': {
+                    'superuser': {
+                        'username': 'postgres',
+                        'password': NO_VALUE_MSG
+                    },
+                    'replication': {
+                        'username': 'replicator',
+                        'password': NO_VALUE_MSG
+                    }
+                }
+            },
+            'tags': {
+                'failover_priority': 1,
+                'noloadbalance': False,
+                'clonefrom': True,
+                'nosync': False,
+            }
+        }
+
+        dynamic_config = Config.get_default_config()
+        # to properly dump CaseInsensitiveDict as YAML later
+        dynamic_config['postgresql']['parameters'] = dict(dynamic_config['postgresql']['parameters'])
+        config = Config('', None).local_configuration  # Get values from env
+        config.setdefault('bootstrap', {})['dcs'] = dynamic_config
+        config.setdefault('postgresql', {})
+        del config['bootstrap']['dcs']['standby_cluster']
+
+        patch_config(template_config, config)
+        return template_config
+
+    @abc.abstractmethod
+    def generate(self) -> None:
+        """Generate config and store in :attr:`~AbstractConfigGenerator.config`."""
+
+    @staticmethod
+    def _format_block(block: Any, line_prefix: str = '') -> str:
+        """Format a single YAML block.
+
+        .. note::
+            Optionally the formatted block could be indented with the *line_prefix*
+
+        :param block: the object that should be formatted to YAML.
+        :param line_prefix: is used for indentation.
+
+        :returns: a formatted and indented *block*.
+        """
+        return line_prefix + yaml.safe_dump(block, default_flow_style=False, line_break='\n',
+                                            allow_unicode=True, indent=2).strip().replace('\n', '\n' + line_prefix)
+
+    def _format_config_section(self, section_name: str) -> Iterator[str]:
+        """Format and yield as single section of the current :attr:`~AbstractConfigGenerator.config`.
+
+        .. note::
+            If the section is a :class:`dict` object we put an empty line before it.
+
+        :param section_name: a section name in the :attr:`~AbstractConfigGenerator.config`.
+
+        :yields: a formatted section in case if it exists in the :attr:`~AbstractConfigGenerator.config`.
+        """
+        if section_name in self.config:
+            if isinstance(self.config[section_name], dict):
+                yield ''
+            yield self._format_block({section_name: self.config[section_name]})
+
+    def _format_config(self) -> Iterator[str]:
+        """Format current :attr:`~AbstractConfigGenerator.config` and enrich it with some comments.
+
+        :yields: formatted lines or blocks that represent a text output of the YAML document.
+        """
+        for name in ('scope', 'namespace', 'name', 'log', 'restapi', 'ctl', 'citus',
+                     'consul', 'etcd', 'etcd3', 'exhibitor', 'kubernetes', 'raft', 'zookeeper'):
+            yield from self._format_config_section(name)
+
+        if 'bootstrap' in self.config:
+            yield '\n# The bootstrap configuration. Works only when the cluster is not yet initialized.'
+            yield '# If the cluster is already initialized, all changes in the `bootstrap` section are ignored!'
+            yield 'bootstrap:'
+            if 'dcs' in self.config['bootstrap']:
+                yield '  # This section will be written into <dcs>:/<namespace>/<scope>/config after initializing'
+                yield '  # new cluster and all other cluster members will use it as a `global configuration`.'
+                yield '  # WARNING! If you want to change any of the parameters that were set up'
+                yield '  # via `bootstrap.dcs` section, please use `patronictl edit-config`!'
+                yield '  dcs:'
+                for name in ('loop_wait', 'retry_timeout', 'ttl'):
+                    if name in self.config['bootstrap']['dcs']:
+                        yield self._format_block({name: self.config['bootstrap']['dcs'].pop(name)}, '    ')
+
+                for name, value in self.config['bootstrap']['dcs'].items():
+                    yield self._format_block({name: value}, '    ')
+
+        for name in ('postgresql', 'watchdog', 'tags'):
+            yield from self._format_config_section(name)
+
+    def _write_config_to_fd(self, fd: TextIO) -> None:
+        """Format and write current :attr:`~AbstractConfigGenerator.config` to provided file descriptor.
+
+        :param fd: where to write the config file. Could be ``sys.stdout`` or the real file.
+        """
+        fd.write('\n'.join(self._format_config()))
+
+    def write_config(self) -> None:
+        """Write current :attr:`~AbstractConfigGenerator.config` to the output file if provided, to stdout otherwise."""
+        if self.output_file:
+            dir_path = os.path.dirname(self.output_file)
+            if dir_path and not os.path.isdir(dir_path):
+                os.makedirs(dir_path)
+            with open(self.output_file, 'w', encoding='UTF-8') as output_file:
+                self._write_config_to_fd(output_file)
+        else:
+            self._write_config_to_fd(sys.stdout)
+
+
+class SampleConfigGenerator(AbstractConfigGenerator):
+    """Object representing the generated sample Patroni config.
+
+    Sane defults are used based on the gathered PG version.
+    """
+
+    @property
+    def get_auth_method(self) -> str:
+        """Return the preferred authentication method for a specific PG version if provided or the default ``md5``.
+
+        :returns: :class:`str` value for the preferred authentication method.
+        """
+        return 'scram-sha-256' if self.pg_major and self.pg_major >= 100000 else 'md5'
+
+    def _get_int_major_version(self) -> int:
+        """Get major PostgreSQL version from the binary as an integer.
+
+        :returns: an integer PostgreSQL major version representation gathered from the PostgreSQL binary.
+                  See :func:`~patroni.postgresql.misc.postgres_major_version_to_int` and
+                  :func:`~patroni.utils.get_major_version`.
+        """
+        postgres_bin = ((self.config.get('postgresql') or {}).get('bin_name') or {}).get('postgres', 'postgres')
+        return postgres_major_version_to_int(get_major_version(self.config['postgresql'].get('bin_dir'), postgres_bin))
+
+    def generate(self) -> None:
+        """Generate sample config using some sane defaults and update :attr:`~AbstractConfigGenerator.config`."""
+        self.pg_major = self._get_int_major_version()
+
+        self.config['postgresql']['parameters'] = {'password_encryption': self.get_auth_method}
+        username = self.config["postgresql"]["authentication"]["replication"]["username"]
+        self.config['postgresql']['pg_hba'] = [
+            f'host all all all {self.get_auth_method}',
+            f'host replication {username} all {self.get_auth_method}'
+        ]
+
+        # add version-specific configuration
+        wal_keep_param = 'wal_keep_segments' if self.pg_major < 130000 else 'wal_keep_size'
+        self.config['bootstrap']['dcs']['postgresql']['parameters'][wal_keep_param] = \
+            ConfigHandler.CMDLINE_OPTIONS[wal_keep_param][0]
+
+        wal_level = 'hot_standby' if self.pg_major < 90600 else 'replica'
+        self.config['bootstrap']['dcs']['postgresql']['parameters']['wal_level'] = wal_level
+
+        self.config['bootstrap']['dcs']['postgresql']['use_pg_rewind'] = True
+        if self.pg_major >= 110000:
+            self.config['postgresql']['authentication'].setdefault(
+                'rewind', {'username': 'rewind_user'}).setdefault('password', NO_VALUE_MSG)
+
+
+class RunningClusterConfigGenerator(AbstractConfigGenerator):
+    """Object representing the Patroni config generated using information gathered from the running instance.
+
+    :ivar dsn: DSN string for the local instance to get GUC values from (if provided).
+    :ivar parsed_dsn: DSN string parsed into a dictionary (see :func:`~patroni.postgresql.config.parse_dsn`).
+    """
+
+    def __init__(self, output_file: Optional[str] = None, dsn: Optional[str] = None) -> None:
+        """Additionally store the passed dsn (if any) in both original and parsed version and run config generation.
+
+        :param output_file: full path to the output file to be used.
+        :param dsn: DSN string for the local instance to get GUC values from.
+
+        :raises:
+            :exc:`~patroni.exceptions.PatroniException`: if DSN parsing failed.
+        """
+        self.dsn = dsn
+        self.parsed_dsn = {}
+
+        super().__init__(output_file)
+
+    @property
+    def _get_hba_conn_types(self) -> Tuple[str, ...]:
+        """Return the connection types allowed.
+
+        If :attr:`~RunningClusterConfigGenerator.pg_major` is defined, adds additional parameters
+        for PostgreSQL version >=16.
+
+        :returns: tuple of the connection methods allowed.
+        """
+        allowed_types = ('local', 'host', 'hostssl', 'hostnossl', 'hostgssenc', 'hostnogssenc')
+        if self.pg_major and self.pg_major >= 160000:
+            allowed_types += ('include', 'include_if_exists', 'include_dir')
+        return allowed_types
+
+    @property
+    def _required_pg_params(self) -> List[str]:
+        """PG configuration prameters that have to be always present in the generated config.
+
+        :returns: list of the parameter names.
+        """
+        return ['hba_file', 'ident_file', 'config_file', 'data_directory'] + \
+            list(ConfigHandler.CMDLINE_OPTIONS.keys())
+
+    def _get_bin_dir_from_running_instance(self) -> str:
+        """Define the directory postgres binaries reside using postmaster's pid executable.
+
+        :returns: path to the PostgreSQL binaries directory.
+
+        :raises:
+            :exc:`~patroni.exceptions.PatroniException`: if:
+
+                * pid could not be obtained from the ``postmaster.pid`` file; or
+                * :exc:`OSError` occured during ``postmaster.pid`` file handling; or
+                * the obtained postmaster pid doesn't exist.
+        """
+        postmaster_pid = None
+        data_dir = self.config['postgresql']['data_dir']
+        try:
+            with open(f"{data_dir}/postmaster.pid", 'r') as pid_file:
+                postmaster_pid = pid_file.readline()
+                if not postmaster_pid:
+                    raise PatroniException('Failed to obtain postmaster pid from postmaster.pid file')
+                postmaster_pid = int(postmaster_pid.strip())
+        except OSError as err:
+            raise PatroniException(f'Error while reading postmaster.pid file: {err}')
+        try:
+            return os.path.dirname(psutil.Process(postmaster_pid).exe())
+        except psutil.NoSuchProcess:
+            raise PatroniException("Obtained postmaster pid doesn't exist.")
+
+    @contextmanager
+    def _get_connection_cursor(self) -> Iterator[Union['cursor', 'Cursor[Any]']]:
+        """Get cursor for the PG connection established based on the stored information.
+
+        :raises:
+            :exc:`~patroni.exceptions.PatroniException`: if :exc:`psycopg.Error` occured.
+        """
+        try:
+            conn = psycopg.connect(dsn=self.dsn,
+                                   password=self.config['postgresql']['authentication']['superuser']['password'])
+            with conn.cursor() as cur:
+                yield cur
+            conn.close()
+        except psycopg.Error as e:
+            raise PatroniException(f'Failed to establish PostgreSQL connection: {e}')
+
+    def _set_pg_params(self, cur: Union['cursor', 'Cursor[Any]']) -> None:
+        """Extend :attr:`~RunningClusterConfigGenerator.config` with the actual PG GUCs values.
+
+        THe following GUC values are set:
+
+            * Non-internal having configuration file, postmaster command line or environment variable
+              as a source.
+
+            * List of the always required parameters (see :meth:`~RunningClusterConfigGenerator._required_pg_params`).
+
+        :param cur: connection cursor to use.
+        """
+        cur.execute("SELECT name, pg_catalog.current_setting(name) FROM pg_catalog.pg_settings "
+                    "WHERE context <> 'internal' "
+                    "AND source IN ('configuration file', 'command line', 'environment variable') "
+                    "AND category <> 'Write-Ahead Log / Recovery Target' "
+                    "AND setting <> '(disabled)' "
+                    "OR name = ANY(%s)", (self._required_pg_params,))
+
+        helper_dict = dict.fromkeys(['port', 'listen_addresses'])
+        self.config['postgresql'].setdefault('parameters', {})
+        for param, value in cur.fetchall():
+            if param == 'data_directory':
+                self.config['postgresql']['data_dir'] = value
+            elif param == 'cluster_name' and value:
+                self.config['scope'] = value
+            elif param in ('archive_command', 'restore_command',
+                           'archive_cleanup_command', 'recovery_end_command',
+                           'ssl_passphrase_command', 'hba_file',
+                           'ident_file', 'config_file'):
+                # write commands to the local config due to security implications
+                # write hba/ident/config_file to local config to ensure they are not removed later
+                self.config['postgresql']['parameters'][param] = value
+            elif param in helper_dict:
+                helper_dict[param] = value
+            else:
+                self.config['bootstrap']['dcs']['postgresql']['parameters'][param] = value
+
+        connect_port = self.parsed_dsn.get('port', os.getenv('PGPORT', helper_dict['port']))
+        self.config['postgresql']['connect_address'] = f'{self._IP}:{connect_port}'
+        self.config['postgresql']['listen'] = f'{helper_dict["listen_addresses"]}:{helper_dict["port"]}'
+
+    def _set_su_params(self) -> None:
+        """Extend :attr:`~RunningClusterConfigGenerator.config` with the superuser auth information.
+
+        Information set is based on the options used for connection.
+        """
+        su_params: Dict[str, str] = {}
+        for conn_param, env_var in _AUTH_ALLOWED_PARAMETERS_MAPPING.items():
+            val = self.parsed_dsn.get(conn_param, os.getenv(env_var))
+            if val:
+                su_params[conn_param] = val
+        patroni_env_su_username = ((self.config.get('authentication') or {}).get('superuser') or {}).get('username')
+        patroni_env_su_pwd = ((self.config.get('authentication') or {}).get('superuser') or {}).get('password')
+        # because we use "username" in the config for some reason
+        su_params['username'] = su_params.pop('user', patroni_env_su_username) or getuser()
+        su_params['password'] = su_params.get('password', patroni_env_su_pwd) or \
+            getpass('Please enter the user password:')
+        self.config['postgresql']['authentication'] = {
+            'superuser': su_params,
+            'replication': {'username': NO_VALUE_MSG, 'password': NO_VALUE_MSG}
+        }
+
+    def _set_conf_files(self) -> None:
+        """Extend :attr:`~RunningClusterConfigGenerator.config` with ``pg_hba.conf`` and ``pg_ident.conf`` content.
+
+        .. note::
+            This function only defines ``postgresql.pg_hba`` and ``postgresql.pg_ident`` when
+            ``hba_file`` and ``ident_file`` are set to the defaults. It may happen these files
+            are located outside of ``PGDATA`` and Patroni doesn't have write permissions for them.
+
+        :raises:
+            :exc:`~patroni.exceptions.PatroniException`: if :exc:`OSError` occured during the conf files handling.
+        """
+        default_hba_path = os.path.join(self.config['postgresql']['data_dir'], 'pg_hba.conf')
+        if self.config['postgresql']['parameters']['hba_file'] == default_hba_path:
+            try:
+                self.config['postgresql']['pg_hba'] = list(
+                    filter(lambda i: i and i.split()[0] in self._get_hba_conn_types, read_stripped(default_hba_path)))
+            except OSError as err:
+                raise PatroniException(f'Failed to read pg_hba.conf: {err}')
+
+        default_ident_path = os.path.join(self.config['postgresql']['data_dir'], 'pg_ident.conf')
+        if self.config['postgresql']['parameters']['ident_file'] == default_ident_path:
+            try:
+                self.config['postgresql']['pg_ident'] = [i for i in read_stripped(default_ident_path)
+                                                         if i and not i.startswith('#')]
+            except OSError as err:
+                raise PatroniException(f'Failed to read pg_ident.conf: {err}')
+            if not self.config['postgresql']['pg_ident']:
+                del self.config['postgresql']['pg_ident']
+
+    def _enrich_config_from_running_instance(self) -> None:
+        """Extend :attr:`~RunningClusterConfigGenerator.config` with the values gathered from the running instance.
+
+        Retrieve the following information from the running PostgreSQL instance:
+
+        * superuser auth parameters (see :meth:`~RunningClusterConfigGenerator._set_su_params`);
+        * some GUC values (see :meth:`~RunningClusterConfigGenerator._set_pg_params`);
+        * ``postgresql.connect_address``, ``postgresql.listen``;
+        * ``postgresql.pg_hba`` and ``postgresql.pg_ident`` (see :meth:`~RunningClusterConfigGenerator._set_conf_files`)
+
+        And redefine ``scope`` with the ``cluster_name`` GUC value if set.
+
+        :raises:
+            :exc:`~patroni.exceptions.PatroniException`: if the provided user doesn't have superuser privileges.
+        """
+        self._set_su_params()
+
+        with self._get_connection_cursor() as cur:
+            self.pg_major = getattr(cur.connection, 'server_version', 0)
+
+            if not parse_bool(cur.connection.info.parameter_status('is_superuser')):
+                raise PatroniException('The provided user does not have superuser privilege')
+
+            self._set_pg_params(cur)
+
+        self._set_conf_files()
+
+    def generate(self) -> None:
+        """Generate config using the info gathered from the specified running PG instance.
+
+        Result is written to :attr:`~RunningClusterConfigGenerator.config`.
+        """
+        if self.dsn:
+            self.parsed_dsn = parse_dsn(self.dsn) or {}
+            if not self.parsed_dsn:
+                raise PatroniException('Failed to parse DSN string')
+
+        self._enrich_config_from_running_instance()
+        self.config['postgresql']['bin_dir'] = self._get_bin_dir_from_running_instance()
+
+
+def generate_config(output_file: str, sample: bool, dsn: Optional[str]) -> None:
+    """Generate Patroni configuration file.
+
+    :param output_file: Full path to the configuration file to be used. If not provided, result is sent to ``stdout``.
+    :param sample: Optional flag. If set, no source instance will be used - generate config with some sane defaults.
+    :param dsn: Optional DSN string for the local instance to get GUC values from.
+    """
+    try:
+        if sample:
+            config_generator = SampleConfigGenerator(output_file)
+        else:
+            config_generator = RunningClusterConfigGenerator(output_file, dsn)
+
+        config_generator.write_config()
+    except PatroniException as e:
+        sys.exit(str(e))
+    except Exception as e:
+        sys.exit(f'Unexpected exception: {e}')

patroni/daemon.py

@@ -1,18 +1,57 @@
+"""Daemon processes abstraction module.
+
+This module implements abstraction classes and functions for creating and managing daemon processes in Patroni.
+Currently it is only used for the main "Thread" of ``patroni`` and ``patroni_raft_controller`` commands.
+"""
 from __future__ import print_function
 
 import abc
+import argparse
 import os
 import signal
-import six
 import sys
 
 from threading import Lock
+from typing import Any, Optional, Type, TYPE_CHECKING
+
+if TYPE_CHECKING:  # pragma: no cover
+    from .config import Config
 
 
-@six.add_metaclass(abc.ABCMeta)
-class AbstractPatroniDaemon(object):
+def get_base_arg_parser() -> argparse.ArgumentParser:
+    """Create a basic argument parser with the arguments used for both patroni and raft controller daemon.
 
-    def __init__(self, config):
+    :returns: 'argparse.ArgumentParser' object
+    """
+    from .config import Config
+    from .version import __version__
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--version', action='version', version='%(prog)s {0}'.format(__version__))
+    parser.add_argument('configfile', nargs='?', default='',
+                        help='Patroni may also read the configuration from the {0} environment variable'
+                        .format(Config.PATRONI_CONFIG_VARIABLE))
+    return parser
+
+
+class AbstractPatroniDaemon(abc.ABC):
+    """A Patroni daemon process.
+
+    .. note::
+
+        When inheriting from :class:`AbstractPatroniDaemon` you are expected to define the methods :func:`_run_cycle`
+        to determine what it should do in each execution cycle, and :func:`_shutdown` to determine what it should do
+        when shutting down.
+
+    :ivar logger: log handler used by this daemon.
+    :ivar config: configuration options for this daemon.
+    """
+
+    def __init__(self, config: 'Config') -> None:
+        """Set up signal handlers, logging handler and configuration.
+
+        :param config: configuration options for this daemon.
+        """
         from patroni.log import PatroniLogger
 
         self.setup_signal_handlers()
@@ -21,20 +60,44 @@ class AbstractPatroniDaemon(object):
         self.config = config
         AbstractPatroniDaemon.reload_config(self, local=True)
 
-    def sighup_handler(self, *args):
+    def sighup_handler(self, *_: Any) -> None:
+        """Handle SIGHUP signals.
+
+        Flag the daemon as "SIGHUP received".
+        """
         self._received_sighup = True
 
-    def api_sigterm(self):
+    def api_sigterm(self) -> bool:
+        """Guarantee only a single SIGTERM is being processed.
+
+        Flag the daemon as "SIGTERM received" with a lock-based approach.
+
+        :returns: ``True`` if the daemon was flagged as "SIGTERM received".
+        """
+        ret = False
         with self._sigterm_lock:
             if not self._received_sigterm:
                 self._received_sigterm = True
-                return True
+                ret = True
+        return ret
 
-    def sigterm_handler(self, *args):
+    def sigterm_handler(self, *_: Any) -> None:
+        """Handle SIGTERM signals.
+
+        Terminate the daemon process through :func:`api_sigterm`.
+        """
         if self.api_sigterm():
             sys.exit()
 
-    def setup_signal_handlers(self):
+    def setup_signal_handlers(self) -> None:
+        """Set up daemon signal handlers.
+
+        Set up SIGHUP and SIGTERM signal handlers.
+
+        .. note::
+
+            SIGHUP is only handled in non-Windows environments.
+        """
         self._received_sighup = False
         self._sigterm_lock = Lock()
         self._received_sigterm = False
@@ -43,19 +106,34 @@ class AbstractPatroniDaemon(object):
         signal.signal(signal.SIGTERM, self.sigterm_handler)
 
     @property
-    def received_sigterm(self):
+    def received_sigterm(self) -> bool:
+        """If daemon was signaled with SIGTERM."""
         with self._sigterm_lock:
             return self._received_sigterm
 
-    def reload_config(self, sighup=False, local=False):
+    def reload_config(self, sighup: bool = False, local: Optional[bool] = False) -> None:
+        """Reload configuration.
+
+        :param sighup: if it is related to a SIGHUP signal.
+                       The sighup parameter could be used in the method overridden in a child class.
+        :param local: will be ``True`` if there are changes in the local configuration file.
+        """
         if local:
             self.logger.reload_config(self.config.get('log', {}))
 
     @abc.abstractmethod
-    def _run_cycle(self):
-        """_run_cycle"""
+    def _run_cycle(self) -> None:
+        """Define what the daemon should do in each execution cycle.
 
-    def run(self):
+        Keep being called in the daemon's main loop until the daemon is eventually terminated.
+        """
+
+    def run(self) -> None:
+        """Run the daemon process.
+
+        Start the logger thread and keep running execution cycles until a SIGTERM is eventually received. Also reload
+        configuration uppon receiving SIGHUP.
+        """
         self.logger.start()
         while not self.received_sigterm:
             if self._received_sighup:
@@ -65,43 +143,31 @@ class AbstractPatroniDaemon(object):
             self._run_cycle()
 
     @abc.abstractmethod
-    def _shutdown(self):
-        """_shutdown"""
+    def _shutdown(self) -> None:
+        """Define what the daemon should do when shutting down."""
 
-    def shutdown(self):
+    def shutdown(self) -> None:
+        """Shut the daemon down when a SIGTERM is received.
+
+        Shut down the daemon process and the logger thread.
+        """
         with self._sigterm_lock:
             self._received_sigterm = True
         self._shutdown()
         self.logger.shutdown()
 
 
-def abstract_main(cls, validator=None):
-    import argparse
+def abstract_main(cls: Type[AbstractPatroniDaemon], configfile: str) -> None:
+    """Create the main entry point of a given daemon process.
 
+    :param cls: a class that should inherit from :class:`AbstractPatroniDaemon`.
+    :param configfile:
+    """
     from .config import Config, ConfigParseError
-    from .version import __version__
-
-    parser = argparse.ArgumentParser()
-    parser.add_argument('--version', action='version', version='%(prog)s {0}'.format(__version__))
-    if validator:
-        parser.add_argument('--validate-config', action='store_true', help='Run config validator and exit')
-    parser.add_argument('configfile', nargs='?', default='',
-                        help='Patroni may also read the configuration from the {0} environment variable'
-                        .format(Config.PATRONI_CONFIG_VARIABLE))
-    args = parser.parse_args()
-    validate_config = validator and args.validate_config
     try:
-        if validate_config:
-            Config(args.configfile, validator=validator)
-            sys.exit()
-
-        config = Config(args.configfile)
+        config = Config(configfile)
     except ConfigParseError as e:
-        if e.value:
-            print(e.value, file=sys.stderr)
-        if not validate_config:
-            parser.print_help()
-        sys.exit(1)
+        sys.exit(e.value)
 
     controller = cls(config)
     try:

patroni/dcs/consul.py

@@ -8,15 +8,20 @@ import ssl
 import time
 import urllib3
 
-from collections import namedtuple
+from collections import defaultdict
 from consul import ConsulException, NotFound, base
+from http.client import HTTPException
 from urllib3.exceptions import HTTPError
-from six.moves.urllib.parse import urlencode, urlparse, quote
-from six.moves.http_client import HTTPException
+from urllib.parse import urlencode, urlparse, quote
+from typing import Any, Callable, Dict, List, Mapping, NamedTuple, Optional, Union, Tuple, TYPE_CHECKING
 
-from . import AbstractDCS, Cluster, ClusterConfig, Failover, Leader, Member, SyncState, TimelineHistory
+from . import AbstractDCS, Cluster, ClusterConfig, Failover, Leader, Member, Status, SyncState, \
+    TimelineHistory, ReturnFalseException, catch_return_false_exception
 from ..exceptions import DCSError
+from ..postgresql.mpp import AbstractMPP
 from ..utils import deep_compare, parse_bool, Retry, RetryFailedError, split_host_port, uri, USER_AGENT
+if TYPE_CHECKING:  # pragma: no cover
+    from ..config import Config
 
 logger = logging.getLogger(__name__)
 
@@ -37,12 +42,68 @@ class InvalidSession(ConsulException):
     """invalid session"""
 
 
-Response = namedtuple('Response', 'code,headers,body,content')
+class ConsulAgentService(base.Consul.Agent.Service):
+    """
+    Consul.Agent.Session with support of ``tagged_addresses``.
+
+    We do it in the Patroni code because ``python-consul`` and
+    ``python-consul2`` modules don't receive any updates for at least 3 years.
+    """
+
+    def register(self, name: str, service_id: Optional[str] = None, address: Optional[str] = None,
+                 port: Optional[int] = None, tags: Optional[List[str]] = None, check: Optional[Dict[str, str]] = None,
+                 token: Optional[str] = None, enable_tag_override: bool = False,
+                 tagged_addresses: Optional[Dict[str, Dict[str, Union[str, int]]]] = None, **kwargs: Any) -> bool:
+        """Add a new service to the local agent.
+
+        :param name: name of the service.
+        :param service_id: service id, optional, if not provided *name* is used.
+        :param address: will default to the address of the agent if not provided.
+        :param port: port on which the service is available.
+        :param tagged_addresses: additional addresses for a node or service.
+        :tags: a list of string values that add service-level labels.
+        :enable_tag_override: optional ``bool`` that enable you to modify a service tags from servers
+                              (consul agent role server). Default is set to ``False``.
+        :check: an optional health check for this service.
+        :token: an optional ACL token to apply to this request.
+
+        :returns: ``True`` if the service was successfully registered/updated, otherwise ``False``.
+        """
+        payload: Dict[str, Any] = {'name': name}
+
+        if enable_tag_override:
+            payload['enabletagoverride'] = enable_tag_override
+        if service_id:
+            payload['id'] = service_id
+        if address:
+            payload['address'] = address
+        if port:
+            payload['port'] = port
+        if tagged_addresses:
+            payload['tagged_addresses'] = tagged_addresses
+        if tags:
+            payload['tags'] = tags
+        if check:
+            payload['check'] = check
+
+        token = token or self.agent.token
+        params = {'token': token} if token else {}
+
+        return self.agent.http.put(base.CB.bool(), '/v1/agent/service/register',
+                                   params=params, data=json.dumps(payload))
+
+
+class Response(NamedTuple):
+    code: int
+    headers: Union[Mapping[str, str], Mapping[bytes, bytes], None]
+    body: str
+    content: bytes
 
 
 class HTTPClient(object):
 
-    def __init__(self, host='127.0.0.1', port=8500, token=None, scheme='http', verify=True, cert=None, ca_cert=None):
+    def __init__(self, host: str = '127.0.0.1', port: int = 8500, token: Optional[str] = None, scheme: str = 'http',
+                 verify: bool = True, cert: Optional[str] = None, ca_cert: Optional[str] = None) -> None:
         self.token = token
         self._read_timeout = 10
         self.base_uri = uri(scheme, (host, port))
@@ -58,23 +119,23 @@ class HTTPClient(object):
         if ca_cert:
             kwargs['ca_certs'] = ca_cert
         kwargs['cert_reqs'] = ssl.CERT_REQUIRED if verify or ca_cert else ssl.CERT_NONE
-        self.http = urllib3.PoolManager(num_pools=10, maxsize=10, **kwargs)
-        self._ttl = None
+        self.http = urllib3.PoolManager(num_pools=10, maxsize=10, headers={}, **kwargs)
+        self._ttl = 30
 
-    def set_read_timeout(self, timeout):
-        self._read_timeout = timeout/3.0
+    def set_read_timeout(self, timeout: float) -> None:
+        self._read_timeout = timeout / 3.0
 
     @property
-    def ttl(self):
+    def ttl(self) -> int:
         return self._ttl
 
-    def set_ttl(self, ttl):
+    def set_ttl(self, ttl: int) -> bool:
         ret = self._ttl != ttl
         self._ttl = ttl
         return ret
 
     @staticmethod
-    def response(response):
+    def response(response: urllib3.response.HTTPResponse) -> Response:
         content = response.data
         body = content.decode('utf-8')
         if response.status == 500:
@@ -87,14 +148,19 @@ class HTTPClient(object):
                 raise ConsulInternalError(msg)
         return Response(response.status, response.headers, body, content)
 
-    def uri(self, path, params=None):
+    def uri(self, path: str,
+            params: Union[None, Dict[str, Any], List[Tuple[str, Any]], Tuple[Tuple[str, Any], ...]] = None) -> str:
         return '{0}{1}{2}'.format(self.base_uri, path, params and '?' + urlencode(params) or '')
 
-    def __getattr__(self, method):
+    def __getattr__(self, method: str) -> Callable[[Callable[[Response], Union[bool, Any, Tuple[str, Any]]],
+                                                    str, Union[None, Dict[str, Any], List[Tuple[str, Any]]],
+                                                    str, Optional[Dict[str, str]]], Union[bool, Any, Tuple[str, Any]]]:
         if method not in ('get', 'post', 'put', 'delete'):
             raise AttributeError("HTTPClient instance has no attribute '{0}'".format(method))
 
-        def wrapper(callback, path, params=None, data='', headers=None):
+        def wrapper(callback: Callable[[Response], Union[bool, Any, Tuple[str, Any]]], path: str,
+                    params: Union[None, Dict[str, Any], List[Tuple[str, Any]]] = None, data: str = '',
+                    headers: Optional[Dict[str, str]] = None) -> Union[bool, Any, Tuple[str, Any]]:
             # python-consul doesn't allow to specify ttl smaller then 10 seconds
             # because session_ttl_min defaults to 10s, so we have to do this ugly dirty hack...
             if method == 'put' and path == '/v1/session/create':
@@ -105,14 +171,14 @@ class HTTPClient(object):
                     data = data[:-1] + ', ' + ttl + '}'
             if isinstance(params, list):  # starting from v1.1.0 python-consul switched from `dict` to `list` for params
                 params = {k: v for k, v in params}
-            kwargs = {'retries': 0, 'preload_content': False, 'body': data}
+            kwargs: Dict[str, Any] = {'retries': 0, 'preload_content': False, 'body': data}
             if method == 'get' and isinstance(params, dict) and 'index' in params:
                 timeout = float(params['wait'][:-1]) if 'wait' in params else 300
                 # According to the documentation a small random amount of additional wait time is added to the
                 # supplied maximum wait time to spread out the wake up time of any concurrent requests. This adds
                 # up to wait / 16 additional time to the maximum duration. Since our goal is actually getting a
                 # response rather read timeout we will add to the timeout a slightly bigger value.
-                kwargs['timeout'] = timeout + max(timeout/15.0, 1)
+                kwargs['timeout'] = timeout + max(timeout / 15.0, 1)
             else:
                 kwargs['timeout'] = self._read_timeout
             kwargs['headers'] = (headers or {}).copy()
@@ -126,13 +192,43 @@ class HTTPClient(object):
 
 class ConsulClient(base.Consul):
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        """
+        Consul client with Patroni customisations.
+
+        .. note::
+
+            Parameters, *token*, *cert* and *ca_cert* are not passed to the parent class :class:`consul.base.Consul`.
+
+        Original class documentation,
+
+            *token* is an optional ``ACL token``. If supplied it will be used by
+            default for all requests made with this client session. It's still
+            possible to override this token by passing a token explicitly for a
+            request.
+
+            *consistency* sets the consistency mode to use by default for all reads
+            that support the consistency option. It's still possible to override
+            this by passing explicitly for a given request. *consistency* can be
+            either 'default', 'consistent' or 'stale'.
+
+            *dc* is the datacenter that this agent will communicate with.
+            By default, the datacenter of the host is used.
+
+            *verify* is whether to verify the SSL certificate for HTTPS requests
+
+            *cert* client side certificates for HTTPS requests
+
+        :param args: positional arguments to pass to :class:`consul.base.Consul`
+        :param kwargs: keyword arguments, with *cert*, *ca_cert* and *token* removed, passed to
+                       :class:`consul.base.Consul`
+        """
         self._cert = kwargs.pop('cert', None)
         self._ca_cert = kwargs.pop('ca_cert', None)
         self.token = kwargs.get('token')
         super(ConsulClient, self).__init__(*args, **kwargs)
 
-    def http_connect(self, *args, **kwargs):
+    def http_connect(self, *args: Any, **kwargs: Any) -> HTTPClient:
         kwargs.update(dict(zip(['host', 'port', 'scheme', 'verify'], args)))
         if self._cert:
             kwargs['cert'] = self._cert
@@ -142,17 +238,17 @@ class ConsulClient(base.Consul):
             kwargs['token'] = self.token
         return HTTPClient(**kwargs)
 
-    def connect(self, *args, **kwargs):
+    def connect(self, *args: Any, **kwargs: Any) -> HTTPClient:
         return self.http_connect(*args, **kwargs)
 
-    def reload_config(self, config):
+    def reload_config(self, config: Dict[str, Any]) -> None:
         self.http.token = self.token = config.get('token')
         self.consistency = config.get('consistency', 'default')
         self.dc = config.get('dc')
 
 
-def catch_consul_errors(func):
-    def wrapper(*args, **kwargs):
+def catch_consul_errors(func: Callable[..., Any]) -> Callable[..., Any]:
+    def wrapper(*args: Any, **kwargs: Any) -> Any:
         try:
             return func(*args, **kwargs)
         except (RetryFailedError, ConsulException, HTTPException, HTTPError, socket.error, socket.timeout):
@@ -160,24 +256,25 @@ def catch_consul_errors(func):
     return wrapper
 
 
-def force_if_last_failed(func):
-    def wrapper(*args, **kwargs):
-        if wrapper.last_result is False:
+def force_if_last_failed(func: Callable[..., Any]) -> Callable[..., Any]:
+    def wrapper(*args: Any, **kwargs: Any) -> Any:
+        if getattr(wrapper, 'last_result', None) is False:
             kwargs['force'] = True
-        wrapper.last_result = func(*args, **kwargs)
-        return wrapper.last_result
+        last_result = func(*args, **kwargs)
+        setattr(wrapper, 'last_result', last_result)
+        return last_result
 
-    wrapper.last_result = None
+    setattr(wrapper, 'last_result', None)
     return wrapper
 
 
-def service_name_from_scope_name(scope_name):
+def service_name_from_scope_name(scope_name: str) -> str:
     """Translate scope name to service name which can be used in dns.
 
     230 = 253 - len('replica.') - len('.service.consul')
     """
 
-    def replace_char(match):
+    def replace_char(match: Any) -> str:
         c = match.group(0)
         return '-' if c in '. _' else "u{:04d}".format(ord(c))
 
@@ -187,8 +284,9 @@ def service_name_from_scope_name(scope_name):
 
 class Consul(AbstractDCS):
 
-    def __init__(self, config):
-        super(Consul, self).__init__(config)
+    def __init__(self, config: Dict[str, Any], mpp: AbstractMPP) -> None:
+        super(Consul, self).__init__(config, mpp)
+        self._base_path = self._base_path[1:]
         self._scope = config['scope']
         self._session = None
         self.__do_not_watch = False
@@ -196,9 +294,9 @@ class Consul(AbstractDCS):
                             retry_exceptions=(ConsulInternalError, HTTPException,
                                               HTTPError, socket.error, socket.timeout))
 
-        kwargs = {}
         if 'url' in config:
-            r = urlparse(config['url'])
+            url: str = config['url']
+            r = urlparse(url)
             config.update({'scheme': r.scheme, 'host': r.hostname, 'port': r.port or 8500})
         elif 'host' in config:
             host, port = split_host_port(config.get('host', '127.0.0.1:8500'), 8500)
@@ -213,7 +311,7 @@ class Consul(AbstractDCS):
             config['cert'] = (config['cert'], config['key'])
 
         config_keys = ('host', 'port', 'token', 'scheme', 'cert', 'ca_cert', 'dc', 'consistency')
-        kwargs = {p: config.get(p) for p in config_keys if config.get(p)}
+        kwargs: Dict[str, Any] = {p: config.get(p) for p in config_keys if config.get(p)}
 
         verify = config.get('verify')
         if not isinstance(verify, bool):
@@ -222,6 +320,7 @@ class Consul(AbstractDCS):
             kwargs['verify'] = verify
 
         self._client = ConsulClient(**kwargs)
+        self._agent_service = ConsulAgentService(self._client)
         self.set_retry_timeout(config['retry_timeout'])
         self.set_ttl(config.get('ttl') or 30)
         self._last_session_refresh = 0
@@ -238,10 +337,10 @@ class Consul(AbstractDCS):
             self.create_session()
         self._previous_loop_token = self._client.token
 
-    def retry(self, *args, **kwargs):
-        return self._retry.copy()(*args, **kwargs)
+    def retry(self, method: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
+        return self._retry.copy()(method, *args, **kwargs)
 
-    def create_session(self):
+    def create_session(self) -> None:
         while not self._session:
             try:
                 self.refresh_session()
@@ -249,13 +348,14 @@ class Consul(AbstractDCS):
                 logger.info('waiting on consul')
                 time.sleep(5)
 
-    def reload_config(self, config):
+    def reload_config(self, config: Union['Config', Dict[str, Any]]) -> None:
         super(Consul, self).reload_config(config)
 
         consul_config = config.get('consul', {})
         self._client.reload_config(consul_config)
         self._previous_loop_service_tags = self._service_tags
-        self._service_tags = sorted(consul_config.get('service_tags', []))
+        self._service_tags: List[str] = consul_config.get('service_tags', [])
+        self._service_tags.sort()
 
         should_register_service = consul_config.get('register_service', False)
         if should_register_service and not self._register_service:
@@ -264,31 +364,32 @@ class Consul(AbstractDCS):
         self._previous_loop_register_service = self._register_service
         self._register_service = should_register_service
 
-    def set_ttl(self, ttl):
-        if self._client.http.set_ttl(ttl/2.0):  # Consul multiplies the TTL by 2x
+    def set_ttl(self, ttl: int) -> Optional[bool]:
+        if self._client.http.set_ttl(ttl / 2.0):  # Consul multiplies the TTL by 2x
             self._session = None
             self.__do_not_watch = True
+        return None
 
     @property
-    def ttl(self):
-        return self._client.http.ttl
+    def ttl(self) -> int:
+        return self._client.http.ttl * 2  # we multiply the value by 2 because it was divided in the `set_ttl()` method
 
-    def set_retry_timeout(self, retry_timeout):
+    def set_retry_timeout(self, retry_timeout: int) -> None:
         self._retry.deadline = retry_timeout
         self._client.http.set_read_timeout(retry_timeout)
 
-    def adjust_ttl(self):
+    def adjust_ttl(self) -> None:
         try:
             settings = self._client.agent.self()
-            min_ttl = (settings['Config']['SessionTTLMin'] or 10000000000)/1000000000.0
+            min_ttl = (settings['Config']['SessionTTLMin'] or 10000000000) / 1000000000.0
             logger.warning('Changing Session TTL from %s to %s', self._client.http.ttl, min_ttl)
             self._client.http.set_ttl(min_ttl)
         except Exception:
             logger.exception('adjust_ttl')
 
-    def _do_refresh_session(self):
+    def _do_refresh_session(self, force: bool = False) -> bool:
         """:returns: `!True` if it had to create new session"""
-        if self._session and self._last_session_refresh + self._loop_wait > time.time():
+        if not force and self._session and self._last_session_refresh + self._loop_wait > time.time():
             return False
 
         if self._session:
@@ -310,103 +411,116 @@ class Consul(AbstractDCS):
         self._last_session_refresh = time.time()
         return ret
 
-    def refresh_session(self):
+    def refresh_session(self) -> bool:
         try:
             return self.retry(self._do_refresh_session)
         except (ConsulException, RetryFailedError):
             logger.exception('refresh_session')
         raise ConsulError('Failed to renew/create session')
 
-    def client_path(self, path):
-        return super(Consul, self).client_path(path)[1:]
-
     @staticmethod
-    def member(node):
+    def member(node: Dict[str, str]) -> Member:
         return Member.from_node(node['ModifyIndex'], os.path.basename(node['Key']), node.get('Session'), node['Value'])
 
-    def _load_cluster(self):
+    def _cluster_from_nodes(self, nodes: Dict[str, Any]) -> Cluster:
+        # get initialize flag
+        initialize = nodes.get(self._INITIALIZE)
+        initialize = initialize and initialize['Value']
+
+        # get global dynamic configuration
+        config = nodes.get(self._CONFIG)
+        config = config and ClusterConfig.from_node(config['ModifyIndex'], config['Value'])
+
+        # get timeline history
+        history = nodes.get(self._HISTORY)
+        history = history and TimelineHistory.from_node(history['ModifyIndex'], history['Value'])
+
+        # get last known leader lsn and slots
+        status = nodes.get(self._STATUS) or nodes.get(self._LEADER_OPTIME)
+        status = Status.from_node(status and status['Value'])
+
+        # get list of members
+        members = [self.member(n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
+
+        # get leader
+        leader = nodes.get(self._LEADER)
+
+        if leader:
+            member = Member(-1, leader['Value'], None, {})
+            member = ([m for m in members if m.name == leader['Value']] or [member])[0]
+            leader = Leader(leader['ModifyIndex'], leader.get('Session'), member)
+
+        # failover key
+        failover = nodes.get(self._FAILOVER)
+        if failover:
+            failover = Failover.from_node(failover['ModifyIndex'], failover['Value'])
+
+        # get synchronization state
+        sync = nodes.get(self._SYNC)
+        sync = SyncState.from_node(sync and sync['ModifyIndex'], sync and sync['Value'])
+
+        # get failsafe topology
+        failsafe = nodes.get(self._FAILSAFE)
         try:
-            path = self.client_path('/')
-            _, results = self.retry(self._client.kv.get, path, recurse=True)
+            failsafe = json.loads(failsafe['Value']) if failsafe else None
+        except Exception:
+            failsafe = None
 
-            if results is None:
-                raise NotFound
+        return Cluster(initialize, config, leader, status, members, failover, sync, history, failsafe)
 
-            nodes = {}
-            for node in results:
+    @property
+    def _consistency(self) -> str:
+        return 'consistent' if self._ctl else self._client.consistency
+
+    def _postgresql_cluster_loader(self, path: str) -> Cluster:
+        """Load and build the :class:`Cluster` object from DCS, which represents a single PostgreSQL cluster.
+
+        :param path: the path in DCS where to load :class:`Cluster` from.
+
+        :returns: :class:`Cluster` instance.
+        """
+        _, results = self.retry(self._client.kv.get, path, recurse=True, consistency=self._consistency)
+        if results is None:
+            return Cluster.empty()
+        nodes: Dict[str, Dict[str, Any]] = {}
+        for node in results:
+            node['Value'] = (node['Value'] or b'').decode('utf-8')
+            nodes[node['Key'][len(path):]] = node
+
+        return self._cluster_from_nodes(nodes)
+
+    def _mpp_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        """Load and build all PostgreSQL clusters from a single MPP cluster.
+
+        :param path: the path in DCS where to load Cluster(s) from.
+
+        :returns: all MPP groups as :class:`dict`, with group IDs as keys and :class:`Cluster` objects as values.
+        """
+        _, results = self.retry(self._client.kv.get, path, recurse=True, consistency=self._consistency)
+        clusters: Dict[int, Dict[str, Cluster]] = defaultdict(dict)
+        for node in results or []:
+            key = node['Key'][len(path):].split('/', 1)
+            if len(key) == 2 and self._mpp.group_re.match(key[0]):
                 node['Value'] = (node['Value'] or b'').decode('utf-8')
-                nodes[node['Key'][len(path):].lstrip('/')] = node
+                clusters[int(key[0])][key[1]] = node
+        return {group: self._cluster_from_nodes(nodes) for group, nodes in clusters.items()}
 
-            # get initialize flag
-            initialize = nodes.get(self._INITIALIZE)
-            initialize = initialize and initialize['Value']
-
-            # get global dynamic configuration
-            config = nodes.get(self._CONFIG)
-            config = config and ClusterConfig.from_node(config['ModifyIndex'], config['Value'])
-
-            # get timeline history
-            history = nodes.get(self._HISTORY)
-            history = history and TimelineHistory.from_node(history['ModifyIndex'], history['Value'])
-
-            # get last known leader lsn and slots
-            status = nodes.get(self._STATUS)
-            if status:
-                try:
-                    status = json.loads(status['Value'])
-                    last_lsn = status.get(self._OPTIME)
-                    slots = status.get('slots')
-                except Exception:
-                    slots = last_lsn = None
-            else:
-                last_lsn = nodes.get(self._LEADER_OPTIME)
-                last_lsn = last_lsn and last_lsn['Value']
-                slots = None
-
-            try:
-                last_lsn = int(last_lsn)
-            except Exception:
-                last_lsn = 0
-
-            # get list of members
-            members = [self.member(n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
-
-            # get leader
-            leader = nodes.get(self._LEADER)
-            if not self._ctl and leader and leader['Value'] == self._name \
-                    and self._session != leader.get('Session', 'x'):
-                logger.info('I am leader but not owner of the session. Removing leader node')
-                self._client.kv.delete(self.leader_path, cas=leader['ModifyIndex'])
-                leader = None
-
-            if leader:
-                member = Member(-1, leader['Value'], None, {})
-                member = ([m for m in members if m.name == leader['Value']] or [member])[0]
-                leader = Leader(leader['ModifyIndex'], leader.get('Session'), member)
-
-            # failover key
-            failover = nodes.get(self._FAILOVER)
-            if failover:
-                failover = Failover.from_node(failover['ModifyIndex'], failover['Value'])
-
-            # get synchronization state
-            sync = nodes.get(self._SYNC)
-            sync = SyncState.from_node(sync and sync['ModifyIndex'], sync and sync['Value'])
-
-            return Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots)
-        except NotFound:
-            return Cluster(None, None, None, None, [], None, None, None, None)
+    def _load_cluster(
+            self, path: str, loader: Callable[[str], Union[Cluster, Dict[int, Cluster]]]
+    ) -> Union[Cluster, Dict[int, Cluster]]:
+        try:
+            return loader(path)
         except Exception:
             logger.exception('get_cluster')
             raise ConsulError('Consul is not responding properly')
 
     @catch_consul_errors
-    def touch_member(self, data, permanent=False):
+    def touch_member(self, data: Dict[str, Any]) -> bool:
         cluster = self.cluster
         member = cluster and cluster.get_member(self._name, fallback_to_leader=False)
 
         try:
-            create_member = not permanent and self.refresh_session()
+            create_member = self.refresh_session()
         except DCSError:
             return False
 
@@ -424,8 +538,7 @@ class Consul(AbstractDCS):
             return True
 
         try:
-            args = {} if permanent else {'acquire': self._session}
-            self._client.kv.put(self.member_path, json.dumps(data, separators=(',', ':')), **args)
+            self._client.kv.put(self.member_path, json.dumps(data, separators=(',', ':')), acquire=self._session)
             return True
         except InvalidSession:
             self._session = None
@@ -434,36 +547,42 @@ class Consul(AbstractDCS):
             logger.exception('touch_member')
         return False
 
-    def _set_service_name(self):
+    def _set_service_name(self) -> None:
         self._service_name = service_name_from_scope_name(self._scope)
         if self._scope != self._service_name:
             logger.warning('Using %s as consul service name instead of scope name %s', self._service_name, self._scope)
 
     @catch_consul_errors
-    def register_service(self, service_name, **kwargs):
+    def register_service(self, service_name: str, **kwargs: Any) -> bool:
         logger.info('Register service %s, params %s', service_name, kwargs)
-        return self._client.agent.service.register(service_name, **kwargs)
+        return self._agent_service.register(service_name, **kwargs)
 
     @catch_consul_errors
-    def deregister_service(self, service_id):
+    def deregister_service(self, service_id: str) -> bool:
         logger.info('Deregister service %s', service_id)
         # service_id can contain special characters, but is used as part of uri in deregister request
         service_id = quote(service_id)
-        return self._client.agent.service.deregister(service_id)
+        return self._agent_service.deregister(service_id)
 
-    def _update_service(self, data):
+    def _update_service(self, data: Dict[str, Any]) -> Optional[bool]:
         service_name = self._service_name
         role = data['role'].replace('_', '-')
         state = data['state']
-        api_parts = urlparse(data['api_url'])
+        api_url: str = data['api_url']
+        api_parts = urlparse(api_url)
         api_parts = api_parts._replace(path='/{0}'.format(role))
-        conn_parts = urlparse(data['conn_url'])
+        conn_url: str = data['conn_url']
+        conn_parts = urlparse(conn_url)
         check = base.Check.http(api_parts.geturl(), self._service_check_interval,
                                 deregister='{0}s'.format(self._client.http.ttl * 10))
         if self._service_check_tls_server_name is not None:
             check['TLSServerName'] = self._service_check_tls_server_name
         tags = self._service_tags[:]
         tags.append(role)
+        if role == 'master':
+            tags.append('primary')
+        elif role == 'primary':
+            tags.append('master')
         self._previous_loop_service_tags = self._service_tags
         self._previous_loop_token = self._client.token
 
@@ -481,7 +600,7 @@ class Consul(AbstractDCS):
             return self.deregister_service(params['service_id'])
 
         self._previous_loop_register_service = self._register_service
-        if role in ['master', 'replica', 'standby-leader']:
+        if role in ['master', 'primary', 'replica', 'standby-leader']:
             if state != 'running':
                 return
             return self.register_service(service_name, **params)
@@ -489,7 +608,7 @@ class Consul(AbstractDCS):
         logger.warning('Could not register service: unknown role type %s', role)
 
     @force_if_last_failed
-    def update_service(self, old_data, new_data, force=False):
+    def update_service(self, old_data: Dict[str, Any], new_data: Dict[str, Any], force: bool = False) -> Optional[bool]:
         update = False
 
         for key in ['role', 'api_url', 'conn_url', 'state']:
@@ -506,96 +625,133 @@ class Consul(AbstractDCS):
         ):
             return self._update_service(new_data)
 
-    @catch_consul_errors
-    def _do_attempt_to_acquire_leader(self, permanent):
+    def _do_attempt_to_acquire_leader(self, retry: Retry) -> bool:
         try:
-            kwargs = {} if permanent else {'acquire': self._session}
-            return self.retry(self._client.kv.put, self.leader_path, self._name, **kwargs)
+            return retry(self._client.kv.put, self.leader_path, self._name, acquire=self._session)
         except InvalidSession:
-            self._session = None
             logger.error('Our session disappeared from Consul. Will try to get a new one and retry attempt')
-            self.refresh_session()
-            return self.retry(self._client.kv.put, self.leader_path, self._name, acquire=self._session)
+            self._session = None
+            retry.ensure_deadline(0)
 
-    def attempt_to_acquire_leader(self, permanent=False):
-        if not self._session and not permanent:
-            self.refresh_session()
+            retry(self._do_refresh_session)
 
-        ret = self._do_attempt_to_acquire_leader(permanent)
+            retry.ensure_deadline(1, ConsulError('_do_attempt_to_acquire_leader timeout'))
+
+            return retry(self._client.kv.put, self.leader_path, self._name, acquire=self._session)
+
+    @catch_return_false_exception
+    def attempt_to_acquire_leader(self) -> bool:
+        retry = self._retry.copy()
+        self._run_and_handle_exceptions(self._do_refresh_session, retry=retry)
+
+        retry.ensure_deadline(1, ConsulError('attempt_to_acquire_leader timeout'))
+
+        ret = self._run_and_handle_exceptions(self._do_attempt_to_acquire_leader, retry, retry=None)
         if not ret:
             logger.info('Could not take out TTL lock')
 
         return ret
 
-    def take_leader(self):
+    def take_leader(self) -> bool:
         return self.attempt_to_acquire_leader()
 
     @catch_consul_errors
-    def set_failover_value(self, value, index=None):
-        return self._client.kv.put(self.failover_path, value, cas=index)
+    def set_failover_value(self, value: str, version: Optional[int] = None) -> bool:
+        return self._client.kv.put(self.failover_path, value, cas=version)
 
     @catch_consul_errors
-    def set_config_value(self, value, index=None):
-        return self._client.kv.put(self.config_path, value, cas=index)
+    def set_config_value(self, value: str, version: Optional[int] = None) -> bool:
+        return self._client.kv.put(self.config_path, value, cas=version)
 
     @catch_consul_errors
-    def _write_leader_optime(self, last_lsn):
+    def _write_leader_optime(self, last_lsn: str) -> bool:
         return self._client.kv.put(self.leader_optime_path, last_lsn)
 
     @catch_consul_errors
-    def _write_status(self, value):
+    def _write_status(self, value: str) -> bool:
         return self._client.kv.put(self.status_path, value)
 
     @catch_consul_errors
-    def _update_leader(self):
-        if self._session:
-            self.retry(self._client.session.renew, self._session)
-            self._last_session_refresh = time.time()
+    def _write_failsafe(self, value: str) -> bool:
+        return self._client.kv.put(self.failsafe_path, value)
+
+    @staticmethod
+    def _run_and_handle_exceptions(method: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
+        retry = kwargs.pop('retry', None)
+        try:
+            return retry(method, *args, **kwargs) if retry else method(*args, **kwargs)
+        except (RetryFailedError, InvalidSession, HTTPException, HTTPError, socket.error, socket.timeout) as e:
+            raise ConsulError(e)
+        except ConsulException:
+            raise ReturnFalseException
+
+    @catch_return_false_exception
+    def _update_leader(self, leader: Leader) -> bool:
+        retry = self._retry.copy()
+
+        self._run_and_handle_exceptions(self._do_refresh_session, True, retry=retry)
+
+        if self._session and leader.session != self._session:
+            retry.ensure_deadline(1, ConsulError('update_leader timeout'))
+
+            logger.warning('Recreating the leader key due to session mismatch')
+            self._run_and_handle_exceptions(self._client.kv.delete, self.leader_path, cas=leader.version)
+
+            retry.ensure_deadline(0.5, ConsulError('update_leader timeout'))
+
+            self._run_and_handle_exceptions(self._client.kv.put, self.leader_path, self._name, acquire=self._session)
+
         return bool(self._session)
 
     @catch_consul_errors
-    def initialize(self, create_new=True, sysid=''):
+    def initialize(self, create_new: bool = True, sysid: str = '') -> bool:
         kwargs = {'cas': 0} if create_new else {}
         return self.retry(self._client.kv.put, self.initialize_path, sysid, **kwargs)
 
     @catch_consul_errors
-    def cancel_initialization(self):
+    def cancel_initialization(self) -> bool:
         return self.retry(self._client.kv.delete, self.initialize_path)
 
     @catch_consul_errors
-    def delete_cluster(self):
+    def delete_cluster(self) -> bool:
         return self.retry(self._client.kv.delete, self.client_path(''), recurse=True)
 
     @catch_consul_errors
-    def set_history_value(self, value):
+    def set_history_value(self, value: str) -> bool:
         return self._client.kv.put(self.history_path, value)
 
     @catch_consul_errors
-    def _delete_leader(self):
-        cluster = self.cluster
-        if cluster and isinstance(cluster.leader, Leader) and cluster.leader.name == self._name:
-            return self._client.kv.delete(self.leader_path, cas=cluster.leader.index)
+    def _delete_leader(self, leader: Leader) -> bool:
+        return self._client.kv.delete(self.leader_path, cas=int(leader.version))
 
     @catch_consul_errors
-    def set_sync_state_value(self, value, index=None):
-        return self.retry(self._client.kv.put, self.sync_path, value, cas=index)
+    def set_sync_state_value(self, value: str, version: Optional[int] = None) -> Union[int, bool]:
+        retry = self._retry.copy()
+        ret = retry(self._client.kv.put, self.sync_path, value, cas=version)
+        if ret:  # We have no other choise, only read after write :(
+            if not retry.ensure_deadline(0.5):
+                return False
+            _, ret = self.retry(self._client.kv.get, self.sync_path, consistency='consistent')
+            if ret and (ret.get('Value') or b'').decode('utf-8') == value:
+                return ret['ModifyIndex']
+        return False
 
     @catch_consul_errors
-    def delete_sync_state(self, index=None):
-        return self.retry(self._client.kv.delete, self.sync_path, cas=index)
+    def delete_sync_state(self, version: Optional[int] = None) -> bool:
+        return self.retry(self._client.kv.delete, self.sync_path, cas=version)
 
-    def watch(self, leader_index, timeout):
+    def watch(self, leader_version: Optional[int], timeout: float) -> bool:
         self._last_session_refresh = 0
         if self.__do_not_watch:
             self.__do_not_watch = False
             return True
 
-        if leader_index:
+        if leader_version:
             end_time = time.time() + timeout
             while timeout >= 1:
                 try:
-                    idx, _ = self._client.kv.get(self.leader_path, index=leader_index, wait=str(timeout) + 's')
-                    return str(idx) != str(leader_index)
+                    idx, _ = self._client.kv.get(self.leader_path, index=leader_version, wait=str(timeout) + 's')
+                    return str(idx) != str(leader_version)
                 except (ConsulException, HTTPException, HTTPError, socket.error, socket.timeout):
                     logger.exception('watch')
 

patroni/dcs/etcd.py

@@ -6,23 +6,29 @@ import logging
 import os
 import urllib3.util.connection
 import random
-import six
 import socket
 import time
 
+from collections import defaultdict
+from copy import deepcopy
 from dns.exception import DNSException
 from dns import resolver
+from http.client import HTTPException
+from queue import Queue
+from threading import Thread
+from typing import Any, Callable, Collection, Dict, List, Optional, Union, Tuple, Type, TYPE_CHECKING
+from urllib.parse import urlparse
 from urllib3 import Timeout
 from urllib3.exceptions import HTTPError, ReadTimeoutError, ProtocolError
-from six.moves.queue import Queue
-from six.moves.http_client import HTTPException
-from six.moves.urllib_parse import urlparse
-from threading import Thread
 
-from . import AbstractDCS, Cluster, ClusterConfig, Failover, Leader, Member, SyncState, TimelineHistory
+from . import AbstractDCS, Cluster, ClusterConfig, Failover, Leader, Member, Status, SyncState, \
+    TimelineHistory, ReturnFalseException, catch_return_false_exception
 from ..exceptions import DCSError
+from ..postgresql.mpp import AbstractMPP
 from ..request import get as requests_get
 from ..utils import Retry, RetryFailedError, split_host_port, uri, USER_AGENT
+if TYPE_CHECKING:  # pragma: no cover
+    from ..config import Config
 
 logger = logging.getLogger(__name__)
 
@@ -35,18 +41,21 @@ class EtcdError(DCSError):
     pass
 
 
+_AddrInfo = Tuple[socket.AddressFamily, socket.SocketKind, int, str, Union[Tuple[str, int], Tuple[str, int, int, int]]]
+
+
 class DnsCachingResolver(Thread):
 
-    def __init__(self, cache_time=600.0, cache_fail_time=30.0):
+    def __init__(self, cache_time: float = 600.0, cache_fail_time: float = 30.0) -> None:
         super(DnsCachingResolver, self).__init__()
-        self._cache = {}
+        self._cache: Dict[Tuple[str, int], Tuple[float, List[_AddrInfo]]] = {}
         self._cache_time = cache_time
         self._cache_fail_time = cache_fail_time
-        self._resolve_queue = Queue()
+        self._resolve_queue: Queue[Tuple[Tuple[str, int], int]] = Queue()
         self.daemon = True
         self.start()
 
-    def run(self):
+    def run(self) -> None:
         while True:
             (host, port), attempt = self._resolve_queue.get()
             response = self._do_resolve(host, port)
@@ -57,7 +66,7 @@ class DnsCachingResolver(Thread):
                     self.resolve_async(host, port, attempt + 1)
                     time.sleep(1)
 
-    def resolve(self, host, port):
+    def resolve(self, host: str, port: int) -> List[_AddrInfo]:
         current_time = time.time()
         cached_time, response = self._cache.get((host, port), (0, []))
         time_passed = current_time - cached_time
@@ -68,14 +77,14 @@ class DnsCachingResolver(Thread):
                 response = new_response
         return response
 
-    def resolve_async(self, host, port, attempt=0):
+    def resolve_async(self, host: str, port: int, attempt: int = 0) -> None:
         self._resolve_queue.put(((host, port), attempt))
 
-    def remove(self, host, port):
+    def remove(self, host: str, port: int) -> None:
         self._cache.pop((host, port), None)
 
     @staticmethod
-    def _do_resolve(host, port):
+    def _do_resolve(host: str, port: int) -> List[_AddrInfo]:
         try:
             return socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM, socket.IPPROTO_TCP)
         except Exception as e:
@@ -83,21 +92,21 @@ class DnsCachingResolver(Thread):
             return []
 
 
-@six.add_metaclass(abc.ABCMeta)
-class AbstractEtcdClientWithFailover(etcd.Client):
+class AbstractEtcdClientWithFailover(abc.ABC, etcd.Client):
 
-    def __init__(self, config, dns_resolver, cache_ttl=300):
+    ERROR_CLS: Type[Exception]
+
+    def __init__(self, config: Dict[str, Any], dns_resolver: DnsCachingResolver, cache_ttl: int = 300) -> None:
         self._dns_resolver = dns_resolver
         self.set_machines_cache_ttl(cache_ttl)
         self._machines_cache_updated = 0
-        args = {p: config.get(p) for p in ('host', 'port', 'protocol', 'use_proxies', 'username', 'password',
-                                           'cert', 'ca_cert') if config.get(p)}
-        super(AbstractEtcdClientWithFailover, self).__init__(read_timeout=config['retry_timeout'], **args)
+        kwargs = {p: config.get(p) for p in ('host', 'port', 'protocol', 'use_proxies', 'version_prefix',
+                                             'username', 'password', 'cert', 'ca_cert') if config.get(p)}
+        super(AbstractEtcdClientWithFailover, self).__init__(read_timeout=config['retry_timeout'], **kwargs)
         # For some reason python3-etcd on debian and ubuntu are not based on the latest version
         # Workaround for the case when https://github.com/jplana/python-etcd/pull/196 is not applied
         self.http.connection_pool_kw.pop('ssl_version', None)
         self._config = config
-        self._initial_machines_cache = []
         self._load_machines_cache()
         self._allow_reconnect = True
         # allow passing retry argument to api_execute in params
@@ -105,7 +114,7 @@ class AbstractEtcdClientWithFailover(etcd.Client):
         self._read_options.add('retry')
         self._del_conditions.add('retry')
 
-    def _calculate_timeouts(self, etcd_nodes, timeout=None):
+    def _calculate_timeouts(self, etcd_nodes: int, timeout: Optional[float] = None) -> Tuple[int, float, int]:
         """Calculate a request timeout and number of retries per single etcd node.
         In case if the timeout per node is too small (less than one second) we will reduce the number of nodes.
         For the cluster with only one node we will try to do 2 retries.
@@ -132,54 +141,48 @@ class AbstractEtcdClientWithFailover(etcd.Client):
 
         return etcd_nodes, per_node_timeout, per_node_retries - 1
 
-    def reload_config(self, config):
+    def reload_config(self, config: Dict[str, Any]) -> None:
         self.username = config.get('username')
         self.password = config.get('password')
 
-    def _get_headers(self):
+    def _get_headers(self) -> Dict[str, str]:
         basic_auth = ':'.join((self.username, self.password)) if self.username and self.password else None
         return urllib3.make_headers(basic_auth=basic_auth, user_agent=USER_AGENT)
 
-    def _prepare_common_parameters(self, etcd_nodes, timeout=None):
-        kwargs = {'headers': self._get_headers(), 'redirect': self.allow_redirect, 'preload_content': False}
+    def _prepare_common_parameters(self, etcd_nodes: int, timeout: Optional[float] = None) -> Dict[str, Any]:
+        kwargs: Dict[str, Any] = {'headers': self._get_headers(),
+                                  'redirect': self.allow_redirect, 'preload_content': False}
 
         if timeout is not None:
             kwargs.update(retries=0, timeout=timeout)
         else:
             _, per_node_timeout, per_node_retries = self._calculate_timeouts(etcd_nodes)
-            connect_timeout = max(1, per_node_timeout/2)
+            connect_timeout = max(1.0, per_node_timeout / 2.0)
             kwargs.update(timeout=Timeout(connect=connect_timeout, total=per_node_timeout), retries=per_node_retries)
         return kwargs
 
-    def set_machines_cache_ttl(self, cache_ttl):
+    def set_machines_cache_ttl(self, cache_ttl: int) -> None:
         self._machines_cache_ttl = cache_ttl
 
     @abc.abstractmethod
-    def _prepare_get_members(self, etcd_nodes):
+    def _prepare_get_members(self, etcd_nodes: int) -> Dict[str, Any]:
         """returns: request parameters"""
 
     @abc.abstractmethod
-    def _get_members(self, base_uri, **kwargs):
+    def _get_members(self, base_uri: str, **kwargs: Any) -> List[str]:
         """returns: list of clientURLs"""
 
     @property
-    def machines_cache(self):
+    def machines_cache(self) -> List[str]:
         base_uri, cache = self._base_uri, self._machines_cache
         return ([base_uri] if base_uri in cache else []) + [machine for machine in cache if machine != base_uri]
 
-    @property
-    def machines(self):
-        """Original `machines` method(property) of `etcd.Client` class raise exception
-        when it failed to get list of etcd cluster members. This method is being called
-        only when request failed on one of the etcd members during `api_execute` call.
-        For us it's more important to execute original request rather then get new topology
-        of etcd cluster. So we will catch this exception and return empty list of machines.
-        Later, during next `api_execute` call we will forcefully update machines_cache.
+    def _get_machines_list(self, machines_cache: List[str]) -> List[str]:
+        """Gets list of members from Etcd cluster using API
 
-        Also this method implements the same timeout-retry logic as `api_execute`, because
-        the original method was retrying 2 times with the `read_timeout` on each node."""
-
-        machines_cache = self.machines_cache
+        :param machines_cache: initial list of Etcd members
+        :returns: list of clientURLs retrieved from Etcd cluster
+        :raises EtcdConnectionFailed: if failed"""
         kwargs = self._prepare_get_members(len(machines_cache))
 
         for base_uri in machines_cache:
@@ -197,10 +200,30 @@ class AbstractEtcdClientWithFailover(etcd.Client):
 
         raise etcd.EtcdConnectionFailed('No more machines in the cluster')
 
-    def set_read_timeout(self, timeout):
+    @property
+    def machines(self) -> List[str]:
+        """Original `machines` method(property) of `etcd.Client` class raise exception
+        when it failed to get list of etcd cluster members. This method is being called
+        only when request failed on one of the etcd members during `api_execute` call.
+        For us it's more important to execute original request rather then get new topology
+        of etcd cluster. So we will catch this exception and return empty list of machines.
+        Later, during next `api_execute` call we will forcefully update machines_cache.
+
+        Also this method implements the same timeout-retry logic as `api_execute`, because
+        the original method was retrying 2 times with the `read_timeout` on each node.
+
+        After the next refactoring the whole logic was moved to the _get_machines_list() method."""
+
+        return self._get_machines_list(self.machines_cache)
+
+    def set_read_timeout(self, timeout: float) -> None:
         self._read_timeout = timeout
 
-    def _do_http_request(self, retry, machines_cache, request_executor, method, path, fields=None, **kwargs):
+    def _do_http_request(self, retry: Optional[Retry], machines_cache: List[str],
+                         request_executor: Callable[..., urllib3.response.HTTPResponse],
+                         method: str, path: str, fields: Optional[Dict[str, Any]] = None,
+                         **kwargs: Any) -> urllib3.response.HTTPResponse:
+        is_watch_request = isinstance(fields, dict) and fields.get('wait') == 'true'
         if fields is not None:
             kwargs['fields'] = fields
         some_request_failed = False
@@ -223,8 +246,7 @@ class AbstractEtcdClientWithFailover(etcd.Client):
                     # whether the key didn't received an update or there is a network problem.
                     elif i + 1 < len(machines_cache):
                         self.set_base_uri(machines_cache[i + 1])
-                if (isinstance(fields, dict) and fields.get("wait") == "true" and
-                        isinstance(e, (ReadTimeoutError, ProtocolError))):
+                if is_watch_request and isinstance(e, (ReadTimeoutError, ProtocolError)):
                     logger.debug("Watch timed out.")
                     raise etcd.EtcdWatchTimedOut("Watch timed out: {0}".format(e), cause=e)
                 logger.error("Request to server %s failed: %r", base_uri, e)
@@ -236,10 +258,12 @@ class AbstractEtcdClientWithFailover(etcd.Client):
         raise etcd.EtcdConnectionFailed('No more machines in the cluster')
 
     @abc.abstractmethod
-    def _prepare_request(self, kwargs, params=None, method=None):
+    def _prepare_request(self, kwargs: Dict[str, Any], params: Optional[Dict[str, Any]] = None,
+                         method: Optional[str] = None) -> Callable[..., urllib3.response.HTTPResponse]:
         """returns: request_executor"""
 
-    def api_execute(self, path, method, params=None, timeout=None):
+    def api_execute(self, path: str, method: str, params: Optional[Dict[str, Any]] = None,
+                    timeout: Optional[float] = None) -> Any:
         retry = params.pop('retry', None) if isinstance(params, dict) else None
 
         # Update machines_cache if previous attempt of update has failed
@@ -267,6 +291,8 @@ class AbstractEtcdClientWithFailover(etcd.Client):
                         etcd_nodes = len(machines_cache)
                 except Exception as e:
                     logger.debug('Failed to update list of etcd nodes: %r', e)
+                if TYPE_CHECKING:  # pragma: no cover
+                    assert isinstance(retry, Retry)  # etcd.EtcdConnectionFailed is raised only if retry is not None!
                 sleeptime = retry.sleeptime
                 remaining_time = retry.stoptime - sleeptime - time.time()
                 nodes, timeout, retries = self._calculate_timeouts(etcd_nodes, remaining_time)
@@ -277,22 +303,22 @@ class AbstractEtcdClientWithFailover(etcd.Client):
                 retry.sleep_func(sleeptime)
                 retry.update_delay()
                 # We still have some time left. Partially reduce `machines_cache` and retry request
-                kwargs.update(timeout=Timeout(connect=max(1, timeout/2), total=timeout), retries=retries)
+                kwargs.update(timeout=Timeout(connect=max(1.0, timeout / 2.0), total=timeout), retries=retries)
                 machines_cache = machines_cache[:nodes]
 
     @staticmethod
-    def get_srv_record(host):
+    def get_srv_record(host: str) -> List[Tuple[str, int]]:
         try:
             return [(r.target.to_text(True), r.port) for r in resolver.query(host, 'SRV')]
         except DNSException:
             return []
 
-    def _get_machines_cache_from_srv(self, srv, srv_suffix=None):
+    def _get_machines_cache_from_srv(self, srv: str, srv_suffix: Optional[str] = None) -> List[str]:
         """Fetch list of etcd-cluster member by resolving _etcd-server._tcp. SRV record.
         This record should contain list of host and peer ports which could be used to run
         'GET http://{host}:{port}/members' request (peer protocol)"""
 
-        ret = []
+        ret: List[str] = []
         for r in ['-client-ssl', '-client', '-ssl', '', '-server-ssl', '-server']:
             r = '{0}-{1}'.format(r, srv_suffix) if srv_suffix else r
             protocol = 'https' if '-ssl' in r else 'http'
@@ -317,15 +343,15 @@ class AbstractEtcdClientWithFailover(etcd.Client):
             logger.warning('Can not resolve SRV for %s', srv)
         return list(set(ret))
 
-    def _get_machines_cache_from_dns(self, host, port):
+    def _get_machines_cache_from_dns(self, host: str, port: int) -> List[str]:
         """One host might be resolved into multiple ip addresses. We will make list out of it"""
         if self.protocol == 'http':
-            ret = map(lambda res: uri(self.protocol, res[-1][:2]), self._dns_resolver.resolve(host, port))
+            ret = [uri(self.protocol, res[-1][:2]) for res in self._dns_resolver.resolve(host, port)]
             if ret:
                 return list(set(ret))
         return [uri(self.protocol, (host, port))]
 
-    def _get_machines_cache_from_config(self):
+    def _get_machines_cache_from_config(self) -> List[str]:
         if 'proxy' in self._config:
             return [uri(self.protocol, (self._config['host'], self._config['port']))]
 
@@ -341,13 +367,14 @@ class AbstractEtcdClientWithFailover(etcd.Client):
         return machines_cache
 
     @staticmethod
-    def _update_dns_cache(func, machines):
+    def _update_dns_cache(func: Callable[[str, int], None], machines: List[str]) -> None:
         for url in machines:
             r = urlparse(url)
-            port = r.port or (443 if r.scheme == 'https' else 80)
-            func(r.hostname, port)
+            if r.hostname:
+                port = r.port or (443 if r.scheme == 'https' else 80)
+                func(r.hostname, port)
 
-    def _load_machines_cache(self):
+    def _load_machines_cache(self) -> bool:
         """This method should fill up `_machines_cache` from scratch.
         It could happen only in two cases:
         1. During class initialization
@@ -366,38 +393,48 @@ class AbstractEtcdClientWithFailover(etcd.Client):
         # enforce resolving dns name,they might get new ips
         self._update_dns_cache(self._dns_resolver.remove, machines_cache)
 
-        # The etcd cluster could change its topology over time and depending on how we resolve the initial
-        # topology (list of hosts in the Patroni config or DNS records, A or SRV) we might get into the situation
-        # the the real topology doesn't match anymore with the topology resolved from the configuration file.
-        # In case if the "initial" topology is the same as before we will not override the `_machines_cache`.
-        ret = set(machines_cache) != set(self._initial_machines_cache)
-        if ret:
-            self._initial_machines_cache = self._machines_cache = machines_cache
-
-            # After filling up the initial list of machines_cache we should ask etcd-cluster about actual list
-            self._refresh_machines_cache(True)
+        # after filling up the initial list of machines_cache we should ask etcd-cluster about actual list
+        ret = self._refresh_machines_cache(machines_cache)
 
         self._update_machines_cache = False
         return ret
 
-    def _refresh_machines_cache(self, updating_cache=False):
+    def _refresh_machines_cache(self, machines_cache: Optional[List[str]] = None) -> bool:
+        """Get etcd cluster topology using Etcd API and put it to self._machines_cache
+
+        :param machines_cache: the list of nodes we want to run through executing API request
+                               in addition to values stored in the self._machines_cache
+        :returns: `True` if self._machines_cache was updated with new values
+        :raises EtcdException: if failed to get topology and `machines_cache` was specified.
+
+        The self._machines_cache will not be updated if nodes from the list are
+        not accessible or if they are not returning correct results."""
+
         if self._use_proxies:
-            self._machines_cache = self._get_machines_cache_from_config()
+            value = self._get_machines_cache_from_config()
         else:
             try:
-                self._machines_cache = self.machines
+                # we want to go through the list obtained from the config file + last known health topology
+                value = self._get_machines_list(list(set((machines_cache or []) + self.machines_cache)))
             except etcd.EtcdConnectionFailed:
-                if updating_cache:
-                    raise etcd.EtcdException("Could not get the list of servers, "
-                                             "maybe you provided the wrong "
-                                             "host(s) to connect to?")
-                return
+                value = []
+
+        if value:
+            ret = set(self._machines_cache) != set(value)
+            self._machines_cache = value
+        elif machines_cache:  # we are just starting or all nodes were not available at some point
+            raise etcd.EtcdException("Could not get the list of servers, "
+                                     "maybe you provided the wrong "
+                                     "host(s) to connect to?")
+        else:
+            return False
 
         if self._base_uri not in self._machines_cache:
             self.set_base_uri(self._machines_cache[0])
         self._machines_cache_updated = time.time()
+        return ret
 
-    def set_base_uri(self, value):
+    def set_base_uri(self, value: str) -> None:
         if self._base_uri != value:
             logger.info('Selected new etcd server %s', value)
             self._base_uri = value
@@ -407,22 +444,25 @@ class EtcdClient(AbstractEtcdClientWithFailover):
 
     ERROR_CLS = EtcdError
 
-    def __del__(self):
-        if self.http is not None:
-            try:
-                self.http.clear()
-            except (ReferenceError, TypeError, AttributeError):
-                pass
+    def __init__(self, config: Dict[str, Any], dns_resolver: DnsCachingResolver, cache_ttl: int = 300) -> None:
+        super(EtcdClient, self).__init__({**config, 'version_prefix': None}, dns_resolver, cache_ttl)
 
-    def _prepare_get_members(self, etcd_nodes):
+    def __del__(self) -> None:
+        try:
+            self.http.clear()
+        except (ReferenceError, TypeError, AttributeError):
+            pass
+
+    def _prepare_get_members(self, etcd_nodes: int) -> Dict[str, Any]:
         return self._prepare_common_parameters(etcd_nodes)
 
-    def _get_members(self, base_uri, **kwargs):
+    def _get_members(self, base_uri: str, **kwargs: Any) -> List[str]:
         response = self.http.request(self._MGET, base_uri + self.version_prefix + '/machines', **kwargs)
         data = self._handle_server_response(response).data.decode('utf-8')
         return [m.strip() for m in data.split(',') if m.strip()]
 
-    def _prepare_request(self, kwargs, params=None, method=None):
+    def _prepare_request(self, kwargs: Dict[str, Any], params: Optional[Dict[str, Any]] = None,
+                         method: Optional[str] = None) -> Callable[..., urllib3.response.HTTPResponse]:
         kwargs['fields'] = params
         if method in (self._MPOST, self._MPUT):
             kwargs['encode_multipart'] = False
@@ -431,25 +471,32 @@ class EtcdClient(AbstractEtcdClientWithFailover):
 
 class AbstractEtcd(AbstractDCS):
 
-    def __init__(self, config, client_cls, retry_errors_cls):
-        super(AbstractEtcd, self).__init__(config)
+    def __init__(self, config: Dict[str, Any], mpp: AbstractMPP, client_cls: Type[AbstractEtcdClientWithFailover],
+                 retry_errors_cls: Union[Type[Exception], Tuple[Type[Exception], ...]]) -> None:
+        super(AbstractEtcd, self).__init__(config, mpp)
         self._retry = Retry(deadline=config['retry_timeout'], max_delay=1, max_tries=-1,
                             retry_exceptions=retry_errors_cls)
         self._ttl = int(config.get('ttl') or 30)
-        self._client = self.get_etcd_client(config, client_cls)
+        self._abstract_client = self.get_etcd_client(config, client_cls)
         self.__do_not_watch = False
         self._has_failed = False
 
-    def reload_config(self, config):
+    @property
+    @abc.abstractmethod
+    def _client(self) -> AbstractEtcdClientWithFailover:
+        """return correct type of etcd client"""
+
+    def reload_config(self, config: Union['Config', Dict[str, Any]]) -> None:
         super(AbstractEtcd, self).reload_config(config)
         self._client.reload_config(config.get(self.__class__.__name__.lower(), {}))
 
-    def retry(self, *args, **kwargs):
+    def retry(self, method: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
         retry = self._retry.copy()
         kwargs['retry'] = retry
-        return retry(*args, **kwargs)
+        return retry(method, *args, **kwargs)
 
-    def _handle_exception(self, e, name='', do_sleep=False, raise_ex=None):
+    def _handle_exception(self, e: Exception, name: str = '', do_sleep: bool = False,
+                          raise_ex: Optional[Exception] = None) -> None:
         if not self._has_failed:
             logger.exception(name)
         else:
@@ -460,18 +507,43 @@ class AbstractEtcd(AbstractDCS):
         if isinstance(raise_ex, Exception):
             raise raise_ex
 
-    @staticmethod
-    def set_socket_options(sock, socket_options):
+    def handle_etcd_exceptions(self, func: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
+        try:
+            retval = func(self, *args, **kwargs)
+            self._has_failed = False
+            return retval
+        except (RetryFailedError, etcd.EtcdException) as e:
+            self._handle_exception(e)
+            return False
+        except Exception as e:
+            self._handle_exception(e, raise_ex=self._client.ERROR_CLS('unexpected error'))
+
+    def _run_and_handle_exceptions(self, method: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
+        retry = kwargs.pop('retry', self.retry)
+        try:
+            return retry(method, *args, **kwargs) if retry else method(*args, **kwargs)
+        except (RetryFailedError, etcd.EtcdConnectionFailed) as e:
+            raise self._client.ERROR_CLS(e)
+        except etcd.EtcdException as e:
+            self._handle_exception(e)
+            raise ReturnFalseException
+        except Exception as e:
+            self._handle_exception(e, raise_ex=self._client.ERROR_CLS('unexpected error'))
+
+    def set_socket_options(self, sock: socket.socket,
+                           socket_options: Optional[Collection[Tuple[int, int, int]]]) -> None:
         if socket_options:
             for opt in socket_options:
                 sock.setsockopt(*opt)
 
-    def get_etcd_client(self, config, client_cls):
+    def get_etcd_client(self, config: Dict[str, Any],
+                        client_cls: Type[AbstractEtcdClientWithFailover]) -> AbstractEtcdClientWithFailover:
+        config = deepcopy(config)
         if 'proxy' in config:
             config['use_proxies'] = True
             config['url'] = config['proxy']
 
-        if 'url' in config:
+        if 'url' in config and isinstance(config['url'], str):
             r = urlparse(config['url'])
             config.update({'protocol': r.scheme, 'host': r.hostname, 'port': r.port or 2379,
                            'username': r.username, 'password': r.password})
@@ -480,13 +552,14 @@ class AbstractEtcd(AbstractDCS):
             default_port = config.pop('port', 2379)
             protocol = config.get('protocol', 'http')
 
-            if isinstance(hosts, six.string_types):
+            if isinstance(hosts, str):
                 hosts = hosts.split(',')
 
-            config['hosts'] = []
+            config_hosts: List[str] = []
             for value in hosts:
-                if isinstance(value, six.string_types):
-                    config['hosts'].append(uri(protocol, split_host_port(value.strip(), default_port)))
+                if isinstance(value, str):
+                    config_hosts.append(uri(protocol, split_host_port(value.strip(), default_port)))
+            config['hosts'] = config_hosts
         elif 'host' in config:
             host, port = split_host_port(config['host'], 2379)
             config['host'] = host
@@ -505,8 +578,10 @@ class AbstractEtcd(AbstractDCS):
 
         dns_resolver = DnsCachingResolver()
 
-        def create_connection_patched(address, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
-                                      source_address=None, socket_options=None):
+        def create_connection_patched(
+                address: Tuple[str, int], timeout: Any = object(),
+                source_address: Optional[Any] = None, socket_options: Optional[Collection[Tuple[int, int, int]]] = None
+        ) -> socket.socket:
             host, port = address
             if host.startswith('['):
                 host = host.strip('[]')
@@ -516,7 +591,7 @@ class AbstractEtcd(AbstractDCS):
                 try:
                     sock = socket.socket(af, socktype, proto)
                     self.set_socket_options(sock, socket_options)
-                    if timeout is not socket._GLOBAL_DEFAULT_TIMEOUT:
+                    if timeout is None or isinstance(timeout, (float, int)):
                         sock.settimeout(timeout)
                     if source_address:
                         sock.bind(source_address)
@@ -547,196 +622,230 @@ class AbstractEtcd(AbstractDCS):
                 time.sleep(5)
         return client
 
-    def set_ttl(self, ttl):
+    def set_ttl(self, ttl: int) -> Optional[bool]:
         ttl = int(ttl)
         ret = self._ttl != ttl
         self._ttl = ttl
-        self._client.set_machines_cache_ttl(ttl*10)
+        self._client.set_machines_cache_ttl(ttl * 10)
         return ret
 
     @property
-    def ttl(self):
+    def ttl(self) -> int:
         return self._ttl
 
-    def set_retry_timeout(self, retry_timeout):
+    def set_retry_timeout(self, retry_timeout: int) -> None:
         self._retry.deadline = retry_timeout
         self._client.set_read_timeout(retry_timeout)
 
 
-def catch_etcd_errors(func):
-    def wrapper(self, *args, **kwargs):
-        try:
-            retval = func(self, *args, **kwargs) is not None
-            self._has_failed = False
-            return retval
-        except (RetryFailedError, etcd.EtcdException) as e:
-            self._handle_exception(e)
-            return False
-        except Exception as e:
-            self._handle_exception(e, raise_ex=self._client.ERROR_CLS('unexpected error'))
-
+def catch_etcd_errors(func: Callable[..., Any]) -> Any:
+    def wrapper(self: AbstractEtcd, *args: Any, **kwargs: Any) -> Any:
+        return self.handle_etcd_exceptions(func, *args, **kwargs)
     return wrapper
 
 
 class Etcd(AbstractEtcd):
 
-    def __init__(self, config):
-        super(Etcd, self).__init__(config, EtcdClient, (etcd.EtcdLeaderElectionInProgress, EtcdRaftInternal))
+    def __init__(self, config: Dict[str, Any], mpp: AbstractMPP) -> None:
+        super(Etcd, self).__init__(config, mpp, EtcdClient, (etcd.EtcdLeaderElectionInProgress, EtcdRaftInternal))
         self.__do_not_watch = False
 
-    def set_ttl(self, ttl):
+    @property
+    def _client(self) -> EtcdClient:
+        if TYPE_CHECKING:  # pragma: no cover
+            assert isinstance(self._abstract_client, EtcdClient)
+        return self._abstract_client
+
+    def set_ttl(self, ttl: int) -> Optional[bool]:
         self.__do_not_watch = super(Etcd, self).set_ttl(ttl)
+        return None
 
     @staticmethod
-    def member(node):
+    def member(node: etcd.EtcdResult) -> Member:
         return Member.from_node(node.modifiedIndex, os.path.basename(node.key), node.ttl, node.value)
 
-    def _load_cluster(self):
+    def _cluster_from_nodes(self, etcd_index: int, nodes: Dict[str, etcd.EtcdResult]) -> Cluster:
+        # get initialize flag
+        initialize = nodes.get(self._INITIALIZE)
+        initialize = initialize and initialize.value
+
+        # get global dynamic configuration
+        config = nodes.get(self._CONFIG)
+        config = config and ClusterConfig.from_node(config.modifiedIndex, config.value)
+
+        # get timeline history
+        history = nodes.get(self._HISTORY)
+        history = history and TimelineHistory.from_node(history.modifiedIndex, history.value)
+
+        # get last know leader lsn and slots
+        status = nodes.get(self._STATUS) or nodes.get(self._LEADER_OPTIME)
+        status = Status.from_node(status and status.value)
+
+        # get list of members
+        members = [self.member(n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
+
+        # get leader
+        leader = nodes.get(self._LEADER)
+        if leader:
+            member = Member(-1, leader.value, None, {})
+            member = ([m for m in members if m.name == leader.value] or [member])[0]
+            version = etcd_index if etcd_index > leader.modifiedIndex else leader.modifiedIndex + 1
+            leader = Leader(version, leader.ttl, member)
+
+        # failover key
+        failover = nodes.get(self._FAILOVER)
+        if failover:
+            failover = Failover.from_node(failover.modifiedIndex, failover.value)
+
+        # get synchronization state
+        sync = nodes.get(self._SYNC)
+        sync = SyncState.from_node(sync and sync.modifiedIndex, sync and sync.value)
+
+        # get failsafe topology
+        failsafe = nodes.get(self._FAILSAFE)
+        try:
+            failsafe = json.loads(failsafe.value) if failsafe else None
+        except Exception:
+            failsafe = None
+
+        return Cluster(initialize, config, leader, status, members, failover, sync, history, failsafe)
+
+    def _postgresql_cluster_loader(self, path: str) -> Cluster:
+        """Load and build the :class:`Cluster` object from DCS, which represents a single PostgreSQL cluster.
+
+        :param path: the path in DCS where to load :class:`Cluster` from.
+
+        :returns: :class:`Cluster` instance.
+        """
+        try:
+            result = self.retry(self._client.read, path, recursive=True, quorum=self._ctl)
+        except etcd.EtcdKeyNotFound:
+            return Cluster.empty()
+        nodes = {node.key[len(result.key):].lstrip('/'): node for node in result.leaves}
+        return self._cluster_from_nodes(result.etcd_index, nodes)
+
+    def _mpp_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        """Load and build all PostgreSQL clusters from a single MPP cluster.
+
+        :param path: the path in DCS where to load Cluster(s) from.
+
+        :returns: all MPP groups as :class:`dict`, with group IDs as keys and :class:`Cluster` objects as values.
+        """
+        try:
+            result = self.retry(self._client.read, path, recursive=True, quorum=self._ctl)
+        except etcd.EtcdKeyNotFound:
+            return {}
+
+        clusters: Dict[int, Dict[str, etcd.EtcdResult]] = defaultdict(dict)
+        for node in result.leaves:
+            key = node.key[len(result.key):].lstrip('/').split('/', 1)
+            if len(key) == 2 and self._mpp.group_re.match(key[0]):
+                clusters[int(key[0])][key[1]] = node
+        return {group: self._cluster_from_nodes(result.etcd_index, nodes) for group, nodes in clusters.items()}
+
+    def _load_cluster(
+            self, path: str, loader: Callable[[str], Union[Cluster, Dict[int, Cluster]]]
+    ) -> Union[Cluster, Dict[int, Cluster]]:
         cluster = None
         try:
-            result = self.retry(self._client.read, self.client_path(''), recursive=True)
-            nodes = {node.key[len(result.key):].lstrip('/'): node for node in result.leaves}
-
-            # get initialize flag
-            initialize = nodes.get(self._INITIALIZE)
-            initialize = initialize and initialize.value
-
-            # get global dynamic configuration
-            config = nodes.get(self._CONFIG)
-            config = config and ClusterConfig.from_node(config.modifiedIndex, config.value)
-
-            # get timeline history
-            history = nodes.get(self._HISTORY)
-            history = history and TimelineHistory.from_node(history.modifiedIndex, history.value)
-
-            # get last know leader lsn and slots
-            status = nodes.get(self._STATUS)
-            if status:
-                try:
-                    status = json.loads(status.value)
-                    last_lsn = status.get(self._OPTIME)
-                    slots = status.get('slots')
-                except Exception:
-                    slots = last_lsn = None
-            else:
-                last_lsn = nodes.get(self._LEADER_OPTIME)
-                last_lsn = last_lsn and last_lsn.value
-                slots = None
-
-            try:
-                last_lsn = int(last_lsn)
-            except Exception:
-                last_lsn = 0
-
-            # get list of members
-            members = [self.member(n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
-
-            # get leader
-            leader = nodes.get(self._LEADER)
-            if leader:
-                member = Member(-1, leader.value, None, {})
-                member = ([m for m in members if m.name == leader.value] or [member])[0]
-                index = result.etcd_index if result.etcd_index > leader.modifiedIndex else leader.modifiedIndex + 1
-                leader = Leader(index, leader.ttl, member)
-
-            # failover key
-            failover = nodes.get(self._FAILOVER)
-            if failover:
-                failover = Failover.from_node(failover.modifiedIndex, failover.value)
-
-            # get synchronization state
-            sync = nodes.get(self._SYNC)
-            sync = SyncState.from_node(sync and sync.modifiedIndex, sync and sync.value)
-
-            cluster = Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots)
-        except etcd.EtcdKeyNotFound:
-            cluster = Cluster(None, None, None, None, [], None, None, None, None)
+            cluster = loader(path)
         except Exception as e:
             self._handle_exception(e, 'get_cluster', raise_ex=EtcdError('Etcd is not responding properly'))
         self._has_failed = False
+        if TYPE_CHECKING:  # pragma: no cover
+            assert cluster is not None
         return cluster
 
     @catch_etcd_errors
-    def touch_member(self, data, permanent=False):
-        data = json.dumps(data, separators=(',', ':'))
-        return self._client.set(self.member_path, data, None if permanent else self._ttl)
+    def touch_member(self, data: Dict[str, Any]) -> bool:
+        value = json.dumps(data, separators=(',', ':'))
+        return bool(self._client.set(self.member_path, value, self._ttl))
 
     @catch_etcd_errors
-    def take_leader(self):
+    def take_leader(self) -> bool:
         return self.retry(self._client.write, self.leader_path, self._name, ttl=self._ttl)
 
-    def attempt_to_acquire_leader(self, permanent=False):
+    def _do_attempt_to_acquire_leader(self) -> bool:
         try:
-            return bool(self.retry(self._client.write,
-                                   self.leader_path,
-                                   self._name,
-                                   ttl=None if permanent else self._ttl,
-                                   prevExist=False))
+            return bool(self.retry(self._client.write, self.leader_path, self._name, ttl=self._ttl, prevExist=False))
         except etcd.EtcdAlreadyExist:
             logger.info('Could not take out TTL lock')
-        except (RetryFailedError, etcd.EtcdException):
-            pass
-        return False
+            return False
+
+    @catch_return_false_exception
+    def attempt_to_acquire_leader(self) -> bool:
+        return self._run_and_handle_exceptions(self._do_attempt_to_acquire_leader, retry=None)
 
     @catch_etcd_errors
-    def set_failover_value(self, value, index=None):
-        return self._client.write(self.failover_path, value, prevIndex=index or 0)
+    def set_failover_value(self, value: str, version: Optional[int] = None) -> bool:
+        return bool(self._client.write(self.failover_path, value, prevIndex=version or 0))
 
     @catch_etcd_errors
-    def set_config_value(self, value, index=None):
-        return self._client.write(self.config_path, value, prevIndex=index or 0)
+    def set_config_value(self, value: str, version: Optional[int] = None) -> bool:
+        return bool(self._client.write(self.config_path, value, prevIndex=version or 0))
 
     @catch_etcd_errors
-    def _write_leader_optime(self, last_lsn):
-        return self._client.set(self.leader_optime_path, last_lsn)
+    def _write_leader_optime(self, last_lsn: str) -> bool:
+        return bool(self._client.set(self.leader_optime_path, last_lsn))
 
     @catch_etcd_errors
-    def _write_status(self, value):
-        return self._client.set(self.status_path, value)
+    def _write_status(self, value: str) -> bool:
+        return bool(self._client.set(self.status_path, value))
+
+    def _do_update_leader(self) -> bool:
+        try:
+            return self.retry(self._client.write, self.leader_path, self._name,
+                              prevValue=self._name, ttl=self._ttl) is not None
+        except etcd.EtcdKeyNotFound:
+            return self._do_attempt_to_acquire_leader()
 
     @catch_etcd_errors
-    def _update_leader(self):
-        return self.retry(self._client.write, self.leader_path, self._name, prevValue=self._name, ttl=self._ttl)
+    def _write_failsafe(self, value: str) -> bool:
+        return bool(self._client.set(self.failsafe_path, value))
+
+    @catch_return_false_exception
+    def _update_leader(self, leader: Leader) -> bool:
+        return bool(self._run_and_handle_exceptions(self._do_update_leader, retry=None))
 
     @catch_etcd_errors
-    def initialize(self, create_new=True, sysid=""):
-        return self.retry(self._client.write, self.initialize_path, sysid, prevExist=(not create_new))
+    def initialize(self, create_new: bool = True, sysid: str = "") -> bool:
+        return bool(self.retry(self._client.write, self.initialize_path, sysid, prevExist=(not create_new)))
 
     @catch_etcd_errors
-    def _delete_leader(self):
-        return self._client.delete(self.leader_path, prevValue=self._name)
+    def _delete_leader(self, leader: Leader) -> bool:
+        return bool(self._client.delete(self.leader_path, prevValue=self._name))
 
     @catch_etcd_errors
-    def cancel_initialization(self):
-        return self.retry(self._client.delete, self.initialize_path)
+    def cancel_initialization(self) -> bool:
+        return bool(self.retry(self._client.delete, self.initialize_path))
 
     @catch_etcd_errors
-    def delete_cluster(self):
-        return self.retry(self._client.delete, self.client_path(''), recursive=True)
+    def delete_cluster(self) -> bool:
+        return bool(self.retry(self._client.delete, self.client_path(''), recursive=True))
 
     @catch_etcd_errors
-    def set_history_value(self, value):
-        return self._client.write(self.history_path, value)
+    def set_history_value(self, value: str) -> bool:
+        return bool(self._client.write(self.history_path, value))
 
     @catch_etcd_errors
-    def set_sync_state_value(self, value, index=None):
-        return self.retry(self._client.write, self.sync_path, value, prevIndex=index or 0)
+    def set_sync_state_value(self, value: str, version: Optional[int] = None) -> Union[int, bool]:
+        return self.retry(self._client.write, self.sync_path, value, prevIndex=version or 0).modifiedIndex
 
     @catch_etcd_errors
-    def delete_sync_state(self, index=None):
-        return self.retry(self._client.delete, self.sync_path, prevIndex=index or 0)
+    def delete_sync_state(self, version: Optional[int] = None) -> bool:
+        return bool(self.retry(self._client.delete, self.sync_path, prevIndex=version or 0))
 
-    def watch(self, leader_index, timeout):
+    def watch(self, leader_version: Optional[int], timeout: float) -> bool:
         if self.__do_not_watch:
             self.__do_not_watch = False
             return True
 
-        if leader_index:
+        if leader_version:
             end_time = time.time() + timeout
 
             while timeout >= 1:  # when timeout is too small urllib3 doesn't have enough time to connect
                 try:
-                    result = self._client.watch(self.leader_path, index=leader_index, timeout=timeout + 0.5)
+                    result = self._client.watch(self.leader_path, index=leader_version, timeout=timeout + 0.5)
                     self._has_failed = False
                     if result.action == 'compareAndSwap':
                         time.sleep(0.01)

patroni/dcs/exhibitor.py

@@ -3,9 +3,13 @@ import logging
 import random
 import time
 
-from patroni.dcs.zookeeper import ZooKeeper
-from patroni.request import get as requests_get
-from patroni.utils import uri
+from typing import Any, Callable, Dict, List, Union
+
+from . import Cluster
+from .zookeeper import ZooKeeper
+from ..postgresql.mpp import AbstractMPP
+from ..request import get as requests_get
+from ..utils import uri
 
 logger = logging.getLogger(__name__)
 
@@ -14,29 +18,31 @@ class ExhibitorEnsembleProvider(object):
 
     TIMEOUT = 3.1
 
-    def __init__(self, hosts, port, uri_path='/exhibitor/v1/cluster/list', poll_interval=300):
+    def __init__(self, hosts: List[str], port: int,
+                 uri_path: str = '/exhibitor/v1/cluster/list', poll_interval: int = 300) -> None:
         self._exhibitor_port = port
         self._uri_path = uri_path
         self._poll_interval = poll_interval
-        self._exhibitors = hosts
-        self._master_exhibitors = hosts
+        self._exhibitors: List[str] = hosts
+        self._boot_exhibitors = hosts
         self._zookeeper_hosts = ''
         self._next_poll = None
         while not self.poll():
             logger.info('waiting on exhibitor')
             time.sleep(5)
 
-    def poll(self):
+    def poll(self) -> bool:
         if self._next_poll and self._next_poll > time.time():
             return False
 
         json = self._query_exhibitors(self._exhibitors)
         if not json:
-            json = self._query_exhibitors(self._master_exhibitors)
+            json = self._query_exhibitors(self._boot_exhibitors)
 
         if isinstance(json, dict) and 'servers' in json and 'port' in json:
             self._next_poll = time.time() + self._poll_interval
-            zookeeper_hosts = ','.join([h + ':' + str(json['port']) for h in sorted(json['servers'])])
+            servers: List[str] = json['servers']
+            zookeeper_hosts = ','.join([h + ':' + str(json['port']) for h in sorted(servers)])
             if self._zookeeper_hosts != zookeeper_hosts:
                 logger.info('ZooKeeper connection string has changed: %s => %s', self._zookeeper_hosts, zookeeper_hosts)
                 self._zookeeper_hosts = zookeeper_hosts
@@ -44,7 +50,7 @@ class ExhibitorEnsembleProvider(object):
                 return True
         return False
 
-    def _query_exhibitors(self, exhibitors):
+    def _query_exhibitors(self, exhibitors: List[str]) -> Union[Dict[str, Any], Any]:
         random.shuffle(exhibitors)
         for host in exhibitors:
             try:
@@ -55,20 +61,20 @@ class ExhibitorEnsembleProvider(object):
         return None
 
     @property
-    def zookeeper_hosts(self):
+    def zookeeper_hosts(self) -> str:
         return self._zookeeper_hosts
 
 
 class Exhibitor(ZooKeeper):
 
-    def __init__(self, config):
+    def __init__(self, config: Dict[str, Any], mpp: AbstractMPP) -> None:
         interval = config.get('poll_interval', 300)
         self._ensemble_provider = ExhibitorEnsembleProvider(config['hosts'], config['port'], poll_interval=interval)
-        config = config.copy()
-        config['hosts'] = self._ensemble_provider.zookeeper_hosts
-        super(Exhibitor, self).__init__(config)
+        super(Exhibitor, self).__init__({**config, 'hosts': self._ensemble_provider.zookeeper_hosts}, mpp)
 
-    def _load_cluster(self):
+    def _load_cluster(
+            self, path: str, loader: Callable[[str], Union[Cluster, Dict[int, Cluster]]]
+    ) -> Union[Cluster, Dict[int, Cluster]]:
         if self._ensemble_provider.poll():
             self._client.set_hosts(self._ensemble_provider.zookeeper_hosts)
-        return super(Exhibitor, self)._load_cluster()
+        return super(Exhibitor, self)._load_cluster(path, loader)

patroni/dcs/raft.py

@@ -4,25 +4,36 @@ import os
 import threading
 import time
 
+from collections import defaultdict
 from pysyncobj import SyncObj, SyncObjConf, replicated, FAIL_REASON
 from pysyncobj.dns_resolver import globalDnsResolver
 from pysyncobj.node import TCPNode
 from pysyncobj.transport import TCPTransport, CONNECTION_STATE
 from pysyncobj.utility import TcpUtility
+from typing import Any, Callable, Collection, Dict, List, Optional, Set, Union, TYPE_CHECKING
 
-from . import AbstractDCS, ClusterConfig, Cluster, Failover, Leader, Member, SyncState, TimelineHistory
+from . import AbstractDCS, ClusterConfig, Cluster, Failover, Leader, Member, Status, SyncState, TimelineHistory
+from ..exceptions import DCSError
+from ..postgresql.mpp import AbstractMPP
 from ..utils import validate_directory
+if TYPE_CHECKING:  # pragma: no cover
+    from ..config import Config
 
 logger = logging.getLogger(__name__)
 
 
+class RaftError(DCSError):
+    pass
+
+
 class _TCPTransport(TCPTransport):
 
-    def __init__(self, syncObj, selfNode, otherNodes):
+    def __init__(self, syncObj: 'DynMemberSyncObj', selfNode: Optional[TCPNode],
+                 otherNodes: Collection[TCPNode]) -> None:
         super(_TCPTransport, self).__init__(syncObj, selfNode, otherNodes)
         self.setOnUtilityMessageCallback('members', syncObj.getMembers)
 
-    def _connectIfNecessarySingle(self, node):
+    def _connectIfNecessarySingle(self, node: TCPNode) -> bool:
         try:
             return super(_TCPTransport, self)._connectIfNecessarySingle(node)
         except Exception as e:
@@ -30,7 +41,7 @@ class _TCPTransport(TCPTransport):
             return False
 
 
-def resolve_host(self):
+def resolve_host(self: TCPNode) -> Optional[str]:
     return globalDnsResolver().resolve(self.host)
 
 
@@ -39,17 +50,19 @@ setattr(TCPNode, 'ip', property(resolve_host))
 
 class SyncObjUtility(object):
 
-    def __init__(self, otherNodes, conf, retry_timeout=10):
+    def __init__(self, otherNodes: Collection[Union[str, TCPNode]], conf: SyncObjConf, retry_timeout: int = 10) -> None:
         self._nodes = otherNodes
-        self._utility = TcpUtility(conf.password, retry_timeout/max(1, len(otherNodes)))
+        self._utility = TcpUtility(conf.password, retry_timeout / max(1, len(otherNodes)))
+        self.__node = next(iter(otherNodes), None)
 
-    def executeCommand(self, command):
+    def executeCommand(self, command: List[Any]) -> Any:
         try:
-            return self._utility.executeCommand(self.__node, command)
+            if self.__node:
+                return self._utility.executeCommand(self.__node, command)
         except Exception:
             return None
 
-    def getMembers(self):
+    def getMembers(self) -> Optional[List[str]]:
         for self.__node in self._nodes:
             response = self.executeCommand(['members'])
             if response:
@@ -58,7 +71,8 @@ class SyncObjUtility(object):
 
 class DynMemberSyncObj(SyncObj):
 
-    def __init__(self, selfAddress, partnerAddrs, conf, retry_timeout=10):
+    def __init__(self, selfAddress: Optional[str], partnerAddrs: Collection[str],
+                 conf: SyncObjConf, retry_timeout: int = 10) -> None:
         self.__early_apply_local_log = selfAddress is not None
         self.applied_local_log = False
 
@@ -75,12 +89,12 @@ class DynMemberSyncObj(SyncObj):
             thread.daemon = True
             thread.start()
 
-    def getMembers(self, args, callback):
+    def getMembers(self, args: Any, callback: Callable[[Any, Any], Any]) -> None:
         callback([{'addr': node.id, 'leader': node == self._getLeader(), 'status': CONNECTION_STATE.CONNECTED
-                   if self.isNodeConnected(node) else CONNECTION_STATE.DISCONNECTED} for node in self.otherNodes] +
-                 [{'addr': self.selfNode.id, 'leader': self._isLeader(), 'status': CONNECTION_STATE.CONNECTED}], None)
+                   if self.isNodeConnected(node) else CONNECTION_STATE.DISCONNECTED} for node in self.otherNodes]
+                 + [{'addr': self.selfNode.id, 'leader': self._isLeader(), 'status': CONNECTION_STATE.CONNECTED}], None)
 
-    def _onTick(self, timeToWait=0.0):
+    def _onTick(self, timeToWait: float = 0.0):
         super(DynMemberSyncObj, self)._onTick(timeToWait)
 
         # The SyncObj calls onReady callback only when cluster got the leader and is ready for writes.
@@ -92,15 +106,16 @@ class DynMemberSyncObj(SyncObj):
 
 class KVStoreTTL(DynMemberSyncObj):
 
-    def __init__(self, on_ready, on_set, on_delete, **config):
+    def __init__(self, on_ready: Optional[Callable[..., Any]], on_set: Optional[Callable[[str, Dict[str, Any]], None]],
+                 on_delete: Optional[Callable[[str], None]], **config: Any) -> None:
         self.__thread = None
         self.__on_set = on_set
         self.__on_delete = on_delete
-        self.__limb = {}
+        self.__limb: Dict[str, Dict[str, Any]] = {}
         self.set_retry_timeout(int(config.get('retry_timeout') or 10))
 
         self_addr = config.get('self_addr')
-        partner_addrs = set(config.get('partner_addrs', []))
+        partner_addrs: Set[str] = set(config.get('partner_addrs', []))
         if config.get('patronictl'):
             if self_addr:
                 partner_addrs.add(self_addr)
@@ -122,22 +137,22 @@ class KVStoreTTL(DynMemberSyncObj):
                            onReady=on_ready, dynamicMembershipChange=True)
 
         super(KVStoreTTL, self).__init__(self_addr, partner_addrs, conf, self.__retry_timeout)
-        self.__data = {}
+        self.__data: Dict[str, Dict[str, Any]] = {}
 
     @staticmethod
-    def __check_requirements(old_value, **kwargs):
-        return ('prevExist' not in kwargs or bool(kwargs['prevExist']) == bool(old_value)) and \
-            ('prevValue' not in kwargs or old_value and old_value['value'] == kwargs['prevValue']) and \
-            (not kwargs.get('prevIndex') or old_value and old_value['index'] == kwargs['prevIndex'])
+    def __check_requirements(old_value: Dict[str, Any], **kwargs: Any) -> bool:
+        return bool(('prevExist' not in kwargs or bool(kwargs['prevExist']) == bool(old_value))
+                    and ('prevValue' not in kwargs or old_value and old_value['value'] == kwargs['prevValue'])
+                    and (kwargs.get('prevIndex') is None or old_value and old_value['index'] == kwargs['prevIndex']))
 
-    def set_retry_timeout(self, retry_timeout):
+    def set_retry_timeout(self, retry_timeout: int) -> None:
         self.__retry_timeout = retry_timeout
 
-    def retry(self, func, *args, **kwargs):
+    def retry(self, func: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
         event = threading.Event()
         ret = {'result': None, 'error': -1}
 
-        def callback(result, error):
+        def callback(result: Any, error: Any) -> None:
             ret.update(result=result, error=error)
             event.set()
 
@@ -156,12 +171,12 @@ class KVStoreTTL(DynMemberSyncObj):
             elif deadline:
                 timeout = deadline - time.time()
                 if timeout <= 0:
-                    break
+                    raise RaftError('timeout')
             time.sleep(1)
         return False
 
     @replicated
-    def _set(self, key, value, **kwargs):
+    def _set(self, key: str, value: Dict[str, Any], **kwargs: Any) -> Union[bool, Dict[str, Any]]:
         old_value = self.__data.get(key, {})
         if not self.__check_requirements(old_value, **kwargs):
             return False
@@ -173,26 +188,32 @@ class KVStoreTTL(DynMemberSyncObj):
         self.__data[key] = value
         if self.__on_set:
             self.__on_set(key, value)
-        return True
+        return value
 
-    def set(self, key, value, ttl=None, **kwargs):
+    def set(self, key: str, value: str, ttl: Optional[int] = None,
+            handle_raft_error: bool = True, **kwargs: Any) -> Union[bool, Dict[str, Any]]:
         old_value = self.__data.get(key, {})
         if not self.__check_requirements(old_value, **kwargs):
             return False
 
-        value = {'value': value, 'updated': time.time()}
-        value['created'] = old_value.get('created', value['updated'])
+        data: Dict[str, Any] = {'value': value, 'updated': time.time()}
+        data['created'] = old_value.get('created', data['updated'])
         if ttl:
-            value['expire'] = value['updated'] + ttl
-        return self.retry(self._set, key, value, **kwargs)
+            data['expire'] = data['updated'] + ttl
+        try:
+            return self.retry(self._set, key, data, **kwargs)
+        except RaftError:
+            if not handle_raft_error:
+                raise
+            return False
 
-    def __pop(self, key):
+    def __pop(self, key: str) -> None:
         self.__data.pop(key)
         if self.__on_delete:
             self.__on_delete(key)
 
     @replicated
-    def _delete(self, key, recursive=False, **kwargs):
+    def _delete(self, key: str, recursive: bool = False, **kwargs: Any) -> bool:
         if recursive:
             for k in list(self.__data.keys()):
                 if k.startswith(key):
@@ -203,38 +224,41 @@ class KVStoreTTL(DynMemberSyncObj):
             self.__pop(key)
         return True
 
-    def delete(self, key, recursive=False, **kwargs):
+    def delete(self, key: str, recursive: bool = False, **kwargs: Any) -> bool:
         if not recursive and not self.__check_requirements(self.__data.get(key, {}), **kwargs):
             return False
-        return self.retry(self._delete, key, recursive=recursive, **kwargs)
+        try:
+            return self.retry(self._delete, key, recursive=recursive, **kwargs)
+        except RaftError:
+            return False
 
     @staticmethod
-    def __values_match(old, new):
+    def __values_match(old: Dict[str, Any], new: Dict[str, Any]) -> bool:
         return all(old.get(n) == new.get(n) for n in ('created', 'updated', 'expire', 'value'))
 
     @replicated
-    def _expire(self, key, value, callback=None):
+    def _expire(self, key: str, value: Dict[str, Any], callback: Optional[Callable[..., Any]] = None) -> None:
         current = self.__data.get(key)
         if current and self.__values_match(current, value):
             self.__pop(key)
 
-    def __expire_keys(self):
+    def __expire_keys(self) -> None:
         for key, value in self.__data.items():
             if value and 'expire' in value and value['expire'] <= time.time() and \
                     not (key in self.__limb and self.__values_match(self.__limb[key], value)):
                 self.__limb[key] = value
 
-                def callback(*args):
+                def callback(*args: Any) -> None:
                     if key in self.__limb and self.__values_match(self.__limb[key], value):
                         self.__limb.pop(key)
                 self._expire(key, value, callback=callback)
 
-    def get(self, key, recursive=False):
+    def get(self, key: str, recursive: bool = False) -> Union[None, Dict[str, Any], Dict[str, Dict[str, Any]]]:
         if not recursive:
             return self.__data.get(key)
         return {k: v for k, v in self.__data.items() if k.startswith(key)}
 
-    def _onTick(self, timeToWait=0.0):
+    def _onTick(self, timeToWait: float = 0.0) -> None:
         super(KVStoreTTL, self)._onTick(timeToWait)
 
         if self._isLeader():
@@ -242,17 +266,17 @@ class KVStoreTTL(DynMemberSyncObj):
         else:
             self.__limb.clear()
 
-    def _autoTickThread(self):
+    def _autoTickThread(self) -> None:
         self.__destroying = False
         while not self.__destroying:
             self.doTick(self.conf.autoTickPeriod)
 
-    def startAutoTick(self):
+    def startAutoTick(self) -> None:
         self.__thread = threading.Thread(target=self._autoTickThread)
         self.__thread.daemon = True
         self.__thread.start()
 
-    def destroy(self):
+    def destroy(self) -> None:
         if self.__thread:
             self.__destroying = True
             self.__thread.join()
@@ -261,8 +285,8 @@ class KVStoreTTL(DynMemberSyncObj):
 
 class Raft(AbstractDCS):
 
-    def __init__(self, config):
-        super(Raft, self).__init__(config)
+    def __init__(self, config: Dict[str, Any], mpp: AbstractMPP) -> None:
+        super(Raft, self).__init__(config, mpp)
         self._ttl = int(config.get('ttl') or 30)
 
         ready_event = threading.Event()
@@ -276,7 +300,7 @@ class Raft(AbstractDCS):
             else:
                 logger.info('waiting on raft')
 
-    def _on_set(self, key, value):
+    def _on_set(self, key: str, value: Dict[str, Any]) -> None:
         leader = (self._sync_obj.get(self.leader_path) or {}).get('value')
         if key == value['created'] == value['updated'] and \
                 (key.startswith(self.members_path) or key == self.leader_path and leader != self._name) or \
@@ -284,35 +308,29 @@ class Raft(AbstractDCS):
                 key in (self.config_path, self.sync_path):
             self.event.set()
 
-    def _on_delete(self, key):
+    def _on_delete(self, key: str) -> None:
         if key == self.leader_path:
             self.event.set()
 
-    def set_ttl(self, ttl):
+    def set_ttl(self, ttl: int) -> Optional[bool]:
         self._ttl = ttl
 
     @property
-    def ttl(self):
+    def ttl(self) -> int:
         return self._ttl
 
-    def set_retry_timeout(self, retry_timeout):
+    def set_retry_timeout(self, retry_timeout: int) -> None:
         self._sync_obj.set_retry_timeout(retry_timeout)
 
-    def reload_config(self, config):
+    def reload_config(self, config: Union['Config', Dict[str, Any]]) -> None:
         super(Raft, self).reload_config(config)
         globalDnsResolver().setTimeouts(self.ttl, self.loop_wait)
 
     @staticmethod
-    def member(key, value):
+    def member(key: str, value: Dict[str, Any]) -> Member:
         return Member.from_node(value['index'], os.path.basename(key), None, value['value'])
 
-    def _load_cluster(self):
-        prefix = self.client_path('')
-        response = self._sync_obj.get(prefix, recursive=True)
-        if not response:
-            return Cluster(None, None, None, None, [], None, None, None, None)
-        nodes = {os.path.relpath(key, prefix).replace('\\', '/'): value for key, value in response.items()}
-
+    def _cluster_from_nodes(self, nodes: Dict[str, Any]) -> Cluster:
         # get initialize flag
         initialize = nodes.get(self._INITIALIZE)
         initialize = initialize and initialize['value']
@@ -326,23 +344,8 @@ class Raft(AbstractDCS):
         history = history and TimelineHistory.from_node(history['index'], history['value'])
 
         # get last know leader lsn and slots
-        status = nodes.get(self._STATUS)
-        if status:
-            try:
-                status = json.loads(status['value'])
-                last_lsn = status.get(self._OPTIME)
-                slots = status.get('slots')
-            except Exception:
-                slots = last_lsn = None
-        else:
-            last_lsn = nodes.get(self._LEADER_OPTIME)
-            last_lsn = last_lsn and last_lsn['value']
-            slots = None
-
-        try:
-            last_lsn = int(last_lsn)
-        except Exception:
-            last_lsn = 0
+        status = nodes.get(self._STATUS) or nodes.get(self._LEADER_OPTIME)
+        status = Status.from_node(status and status['value'])
 
         # get list of members
         members = [self.member(k, n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
@@ -363,60 +366,107 @@ class Raft(AbstractDCS):
         sync = nodes.get(self._SYNC)
         sync = SyncState.from_node(sync and sync['index'], sync and sync['value'])
 
-        return Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots)
+        # get failsafe topology
+        failsafe = nodes.get(self._FAILSAFE)
+        try:
+            failsafe = json.loads(failsafe['value']) if failsafe else None
+        except Exception:
+            failsafe = None
 
-    def _write_leader_optime(self, last_lsn):
-        return self._sync_obj.set(self.leader_optime_path, last_lsn, timeout=1)
+        return Cluster(initialize, config, leader, status, members, failover, sync, history, failsafe)
 
-    def _write_status(self, value):
-        return self._sync_obj.set(self.status_path, value, timeout=1)
+    def _postgresql_cluster_loader(self, path: str) -> Cluster:
+        """Load and build the :class:`Cluster` object from DCS, which represents a single PostgreSQL cluster.
 
-    def _update_leader(self):
-        ret = self._sync_obj.set(self.leader_path, self._name, ttl=self._ttl, prevValue=self._name)
+        :param path: the path in DCS where to load :class:`Cluster` from.
+
+        :returns: :class:`Cluster` instance.
+        """
+        response = self._sync_obj.get(path, recursive=True)
+        if not response:
+            return Cluster.empty()
+        nodes = {key[len(path):]: value for key, value in response.items()}
+        return self._cluster_from_nodes(nodes)
+
+    def _mpp_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        """Load and build all PostgreSQL clusters from a single MPP cluster.
+
+        :param path: the path in DCS where to load Cluster(s) from.
+
+        :returns: all MPP groups as :class:`dict`, with group IDs as keys and :class:`Cluster` objects as values.
+        """
+        clusters: Dict[int, Dict[str, Any]] = defaultdict(dict)
+        response = self._sync_obj.get(path, recursive=True)
+        for key, value in (response or {}).items():
+            key = key[len(path):].split('/', 1)
+            if len(key) == 2 and self._mpp.group_re.match(key[0]):
+                clusters[int(key[0])][key[1]] = value
+        return {group: self._cluster_from_nodes(nodes) for group, nodes in clusters.items()}
+
+    def _load_cluster(
+            self, path: str, loader: Callable[[str], Union[Cluster, Dict[int, Cluster]]]
+    ) -> Union[Cluster, Dict[int, Cluster]]:
+        return loader(path)
+
+    def _write_leader_optime(self, last_lsn: str) -> bool:
+        return self._sync_obj.set(self.leader_optime_path, last_lsn, timeout=1) is not False
+
+    def _write_status(self, value: str) -> bool:
+        return self._sync_obj.set(self.status_path, value, timeout=1) is not False
+
+    def _write_failsafe(self, value: str) -> bool:
+        return self._sync_obj.set(self.failsafe_path, value, timeout=1) is not False
+
+    def _update_leader(self, leader: Leader) -> bool:
+        ret = self._sync_obj.set(self.leader_path, self._name, ttl=self._ttl,
+                                 handle_raft_error=False, prevValue=self._name) is not False
         if not ret and self._sync_obj.get(self.leader_path) is None:
             ret = self.attempt_to_acquire_leader()
         return ret
 
-    def attempt_to_acquire_leader(self, permanent=False):
-        return self._sync_obj.set(self.leader_path, self._name, prevExist=False,
-                                  ttl=None if permanent else self._ttl)
+    def attempt_to_acquire_leader(self) -> bool:
+        return self._sync_obj.set(self.leader_path, self._name, ttl=self._ttl,
+                                  handle_raft_error=False, prevExist=False) is not False
 
-    def set_failover_value(self, value, index=None):
-        return self._sync_obj.set(self.failover_path, value, prevIndex=index)
+    def set_failover_value(self, value: str, version: Optional[int] = None) -> bool:
+        return self._sync_obj.set(self.failover_path, value, prevIndex=version) is not False
 
-    def set_config_value(self, value, index=None):
-        return self._sync_obj.set(self.config_path, value, prevIndex=index)
+    def set_config_value(self, value: str, version: Optional[int] = None) -> bool:
+        return self._sync_obj.set(self.config_path, value, prevIndex=version) is not False
 
-    def touch_member(self, data, permanent=False):
-        data = json.dumps(data, separators=(',', ':'))
-        return self._sync_obj.set(self.member_path, data, None if permanent else self._ttl, timeout=2)
+    def touch_member(self, data: Dict[str, Any]) -> bool:
+        value = json.dumps(data, separators=(',', ':'))
+        return self._sync_obj.set(self.member_path, value, self._ttl, timeout=2) is not False
 
-    def take_leader(self):
-        return self._sync_obj.set(self.leader_path, self._name, ttl=self._ttl)
+    def take_leader(self) -> bool:
+        return self._sync_obj.set(self.leader_path, self._name, ttl=self._ttl) is not False
 
-    def initialize(self, create_new=True, sysid=''):
-        return self._sync_obj.set(self.initialize_path, sysid, prevExist=(not create_new))
+    def initialize(self, create_new: bool = True, sysid: str = '') -> bool:
+        return self._sync_obj.set(self.initialize_path, sysid, prevExist=(not create_new)) is not False
 
-    def _delete_leader(self):
+    def _delete_leader(self, leader: Leader) -> bool:
         return self._sync_obj.delete(self.leader_path, prevValue=self._name, timeout=1)
 
-    def cancel_initialization(self):
+    def cancel_initialization(self) -> bool:
         return self._sync_obj.delete(self.initialize_path)
 
-    def delete_cluster(self):
+    def delete_cluster(self) -> bool:
         return self._sync_obj.delete(self.client_path(''), recursive=True)
 
-    def set_history_value(self, value):
-        return self._sync_obj.set(self.history_path, value)
+    def set_history_value(self, value: str) -> bool:
+        return self._sync_obj.set(self.history_path, value) is not False
 
-    def set_sync_state_value(self, value, index=None):
-        return self._sync_obj.set(self.sync_path, value, prevIndex=index)
+    def set_sync_state_value(self, value: str, version: Optional[int] = None) -> Union[int, bool]:
+        ret = self._sync_obj.set(self.sync_path, value, prevIndex=version)
+        if isinstance(ret, dict):
+            return ret['index']
+        return ret
 
-    def delete_sync_state(self, index=None):
-        return self._sync_obj.delete(self.sync_path, prevIndex=index)
+    def delete_sync_state(self, version: Optional[int] = None) -> bool:
+        return self._sync_obj.delete(self.sync_path, prevIndex=version)
 
-    def watch(self, leader_index, timeout):
+    def watch(self, leader_version: Optional[int], timeout: float) -> bool:
         try:
-            return super(Raft, self).watch(leader_index, timeout)
+            return super(Raft, self).watch(leader_version, timeout)
         finally:
             self.event.clear()

patroni/dcs/zookeeper.py

@@ -1,18 +1,23 @@
 import json
 import logging
 import select
-import six
+import socket
 import time
 
 from kazoo.client import KazooClient, KazooState, KazooRetry
-from kazoo.exceptions import NoNodeError, NodeExistsError, SessionExpiredError
-from kazoo.handlers.threading import SequentialThreadingHandler
-from kazoo.protocol.states import KeeperState
-from kazoo.security import make_acl
+from kazoo.exceptions import ConnectionClosedError, NoNodeError, NodeExistsError, SessionExpiredError
+from kazoo.handlers.threading import AsyncResult, SequentialThreadingHandler
+from kazoo.protocol.states import KeeperState, WatchedEvent, ZnodeStat
+from kazoo.retry import RetryFailedError
+from kazoo.security import ACL, make_acl
+from typing import Any, Callable, Dict, List, Optional, Union, Tuple, TYPE_CHECKING
 
-from . import AbstractDCS, ClusterConfig, Cluster, Failover, Leader, Member, SyncState, TimelineHistory
+from . import AbstractDCS, ClusterConfig, Cluster, Failover, Leader, Member, Status, SyncState, TimelineHistory
 from ..exceptions import DCSError
+from ..postgresql.mpp import AbstractMPP
 from ..utils import deep_compare
+if TYPE_CHECKING:  # pragma: no cover
+    from ..config import Config
 
 logger = logging.getLogger(__name__)
 
@@ -23,14 +28,14 @@ class ZooKeeperError(DCSError):
 
 class PatroniSequentialThreadingHandler(SequentialThreadingHandler):
 
-    def __init__(self, connect_timeout):
+    def __init__(self, connect_timeout: Union[int, float]) -> None:
         super(PatroniSequentialThreadingHandler, self).__init__()
         self.set_connect_timeout(connect_timeout)
 
-    def set_connect_timeout(self, connect_timeout):
-        self._connect_timeout = max(1.0, connect_timeout/2.0)  # try to connect to zookeeper node during loop_wait/2
+    def set_connect_timeout(self, connect_timeout: Union[int, float]) -> None:
+        self._connect_timeout = max(1.0, connect_timeout / 2.0)  # try to connect to zookeeper node during loop_wait/2
 
-    def create_connection(self, *args, **kwargs):
+    def create_connection(self, *args: Any, **kwargs: Any) -> socket.socket:
         """This method is trying to establish connection with one of the zookeeper nodes.
            Somehow strategy "fail earlier and retry more often" works way better comparing to
            the original strategy "try to connect with specified timeout".
@@ -41,16 +46,16 @@ class PatroniSequentialThreadingHandler(SequentialThreadingHandler):
         :param args: always contains `tuple(host, port)` as the first element and could contain
                      `connect_timeout` (negotiated session timeout) as the second element."""
 
-        args = list(args)
-        if len(args) == 0:  # kazoo 2.6.0 slightly changed the way how it calls create_connection method
-            kwargs['timeout'] = max(self._connect_timeout, kwargs.get('timeout', self._connect_timeout*10)/10.0)
-        elif len(args) == 1:
-            args.append(self._connect_timeout)
+        args_list: List[Any] = list(args)
+        if len(args_list) == 0:  # kazoo 2.6.0 slightly changed the way how it calls create_connection method
+            kwargs['timeout'] = max(self._connect_timeout, kwargs.get('timeout', self._connect_timeout * 10) / 10.0)
+        elif len(args_list) == 1:
+            args_list.append(self._connect_timeout)
         else:
-            args[1] = max(self._connect_timeout, args[1]/10.0)
-        return super(PatroniSequentialThreadingHandler, self).create_connection(*args, **kwargs)
+            args_list[1] = max(self._connect_timeout, args_list[1] / 10.0)
+        return super(PatroniSequentialThreadingHandler, self).create_connection(*args_list, **kwargs)
 
-    def select(self, *args, **kwargs):
+    def select(self, *args: Any, **kwargs: Any) -> Any:
         """
         Python 3.XY may raise following exceptions if select/poll are called with an invalid socket:
         - `ValueError`: because fd == -1
@@ -62,15 +67,13 @@ class PatroniSequentialThreadingHandler(SequentialThreadingHandler):
 
         try:
             return super(PatroniSequentialThreadingHandler, self).select(*args, **kwargs)
-        except IOError as e:
-            raise (select.error(e.errno, e.strerror) if six.PY2 else e)
         except (TypeError, ValueError) as e:
-            raise (e if six.PY2 and isinstance(e, TypeError) else select.error(9, str(e)))
+            raise select.error(9, str(e))
 
 
 class PatroniKazooClient(KazooClient):
 
-    def _call(self, request, async_object):
+    def _call(self, request: Tuple[Any], async_object: AsyncResult) -> Optional[bool]:
         # Before kazoo==2.7.0 it wasn't possible to send requests to zookeeper if
         # the connection is in the SUSPENDED state and Patroni was strongly relying on it.
         # The https://github.com/python-zk/kazoo/pull/588 changed it, and now such requests are queued.
@@ -84,10 +87,10 @@ class PatroniKazooClient(KazooClient):
 
 class ZooKeeper(AbstractDCS):
 
-    def __init__(self, config):
-        super(ZooKeeper, self).__init__(config)
+    def __init__(self, config: Dict[str, Any], mpp: AbstractMPP) -> None:
+        super(ZooKeeper, self).__init__(config, mpp)
 
-        hosts = config.get('hosts', [])
+        hosts: Union[str, List[str]] = config.get('hosts', [])
         if isinstance(hosts, list):
             hosts = ','.join(hosts)
 
@@ -96,34 +99,33 @@ class ZooKeeper(AbstractDCS):
         kwargs = {v: config[k] for k, v in mapping.items() if k in config}
 
         if 'set_acls' in config:
-            kwargs['default_acl'] = []
+            default_acl: List[ACL] = []
             for principal, permissions in config['set_acls'].items():
                 normalizedPermissions = [p.upper() for p in permissions]
-                kwargs['default_acl'].append(make_acl(scheme='x509',
-                                                      credential=principal,
-                                                      read='READ' in normalizedPermissions,
-                                                      write='WRITE' in normalizedPermissions,
-                                                      create='CREATE' in normalizedPermissions,
-                                                      delete='DELETE' in normalizedPermissions,
-                                                      admin='ADMIN' in normalizedPermissions,
-                                                      all='ALL' in normalizedPermissions))
+                default_acl.append(make_acl(scheme='x509',
+                                            credential=principal,
+                                            read='READ' in normalizedPermissions,
+                                            write='WRITE' in normalizedPermissions,
+                                            create='CREATE' in normalizedPermissions,
+                                            delete='DELETE' in normalizedPermissions,
+                                            admin='ADMIN' in normalizedPermissions,
+                                            all='ALL' in normalizedPermissions))
+            kwargs['default_acl'] = default_acl
 
         self._client = PatroniKazooClient(hosts, handler=PatroniSequentialThreadingHandler(config['retry_timeout']),
                                           timeout=config['ttl'], connection_retry=KazooRetry(max_delay=1, max_tries=-1,
                                           sleep_func=time.sleep), command_retry=KazooRetry(max_delay=1, max_tries=-1,
-                                          deadline=config['retry_timeout'], sleep_func=time.sleep), **kwargs)
-        self._client.add_listener(self.session_listener)
+                                          deadline=config['retry_timeout'], sleep_func=time.sleep),
+                                          auth_data=list(config.get('auth_data', {}).items()), **kwargs)
 
-        self._fetch_cluster = True
-        self._fetch_status = True
-        self.__last_member_data = None
+        self.__last_member_data: Optional[Dict[str, Any]] = None
 
         self._orig_kazoo_connect = self._client._connection._connect
         self._client._connection._connect = self._kazoo_connect
 
         self._client.start()
 
-    def _kazoo_connect(self, *args):
+    def _kazoo_connect(self, *args: Any) -> Tuple[Union[int, float], Union[int, float]]:
         """Kazoo is using Ping's to determine health of connection to zookeeper. If there is no
         response on Ping after Ping interval (1/2 from read_timeout) it will consider current
         connection dead and try to connect to another node. Without this "magic" it was taking
@@ -136,28 +138,21 @@ class ZooKeeper(AbstractDCS):
         `write_leader_optime()` methods, which also may hang..."""
 
         ret = self._orig_kazoo_connect(*args)
-        return max(self.loop_wait - 2, 2)*1000, ret[1]
+        return max(self.loop_wait - 2, 2) * 1000, ret[1]
 
-    def session_listener(self, state):
-        if state in [KazooState.SUSPENDED, KazooState.LOST]:
-            self.cluster_watcher(None)
+    def _watcher(self, event: WatchedEvent) -> None:
+        if event.state != KazooState.CONNECTED or event.path.startswith(self.client_path('')):
+            self.event.set()
 
-    def status_watcher(self, event):
-        self._fetch_status = True
-        self.event.set()
-
-    def cluster_watcher(self, event):
-        self._fetch_cluster = True
-        self.status_watcher(event)
-
-    def reload_config(self, config):
+    def reload_config(self, config: Union['Config', Dict[str, Any]]) -> None:
         self.set_retry_timeout(config['retry_timeout'])
 
         loop_wait = config['loop_wait']
 
         loop_wait_changed = self._loop_wait != loop_wait
         self._loop_wait = loop_wait
-        self._client.handler.set_connect_timeout(loop_wait)
+        if isinstance(self._client.handler, PatroniSequentialThreadingHandler):
+            self._client.handler.set_connect_timeout(loop_wait)
 
         # We need to reestablish connection to zookeeper if we want to change
         # read_timeout (and Ping interval respectively), because read_timeout
@@ -168,7 +163,7 @@ class ZooKeeper(AbstractDCS):
         if not self.set_ttl(config['ttl']) and loop_wait_changed:
             self._client._connection._socket.close()
 
-    def set_ttl(self, ttl):
+    def set_ttl(self, ttl: int) -> Optional[bool]:
         """It is not possible to change ttl (session_timeout) in zookeeper without
         destroying old session and creating the new one. This method returns `!True`
         if session_timeout has been changed (`restart()` has been called)."""
@@ -179,141 +174,119 @@ class ZooKeeper(AbstractDCS):
             return True
 
     @property
-    def ttl(self):
-        return self._client._session_timeout / 1000.0
+    def ttl(self) -> int:
+        return int(self._client._session_timeout / 1000.0)
 
-    def set_retry_timeout(self, retry_timeout):
+    def set_retry_timeout(self, retry_timeout: int) -> None:
         retry = self._client.retry if isinstance(self._client.retry, KazooRetry) else self._client._retry
         retry.deadline = retry_timeout
 
-    def get_node(self, key, watch=None):
+    def get_node(
+            self, key: str, watch: Optional[Callable[[WatchedEvent], None]] = None
+    ) -> Optional[Tuple[str, ZnodeStat]]:
         try:
             ret = self._client.get(key, watch)
             return (ret[0].decode('utf-8'), ret[1])
         except NoNodeError:
             return None
 
-    def get_status(self, leader):
-        watch = self.status_watcher if not leader or leader.name != self._name else None
-
-        status = self.get_node(self.status_path, watch)
-        if status:
-            try:
-                status = json.loads(status[0])
-                last_lsn = status.get(self._OPTIME)
-                slots = status.get('slots')
-            except Exception:
-                slots = last_lsn = None
-        else:
-            last_lsn = self.get_node(self.leader_optime_path, watch)
-            last_lsn = last_lsn and last_lsn[0]
-            slots = None
-
-        try:
-            last_lsn = int(last_lsn)
-        except Exception:
-            last_lsn = 0
-
-        self._fetch_status = False
-        return last_lsn, slots
+    def get_status(self, path: str, leader: Optional[Leader]) -> Status:
+        status = self.get_node(path + self._STATUS)
+        if not status:
+            status = self.get_node(path + self._LEADER_OPTIME)
+        return Status.from_node(status and status[0])
 
     @staticmethod
-    def member(name, value, znode):
+    def member(name: str, value: str, znode: ZnodeStat) -> Member:
         return Member.from_node(znode.version, name, znode.ephemeralOwner, value)
 
-    def get_children(self, key, watch=None):
+    def get_children(self, key: str) -> List[str]:
         try:
-            return self._client.get_children(key, watch)
+            return self._client.get_children(key)
         except NoNodeError:
             return []
 
-    def load_members(self):
-        members = []
-        for member in self.get_children(self.members_path, self.cluster_watcher):
-            data = self.get_node(self.members_path + member)
+    def load_members(self, path: str) -> List[Member]:
+        members: List[Member] = []
+        for member in self.get_children(path + self._MEMBERS):
+            data = self.get_node(path + self._MEMBERS + member)
             if data is not None:
                 members.append(self.member(member, *data))
         return members
 
-    def _inner_load_cluster(self):
-        self._fetch_cluster = False
-        self.event.clear()
-        nodes = set(self.get_children(self.client_path(''), self.cluster_watcher))
-        if not nodes:
-            self._fetch_cluster = True
+    def _postgresql_cluster_loader(self, path: str) -> Cluster:
+        """Load and build the :class:`Cluster` object from DCS, which represents a single PostgreSQL cluster.
+
+        :param path: the path in DCS where to load :class:`Cluster` from.
+
+        :returns: :class:`Cluster` instance.
+        """
+        nodes = set(self.get_children(path))
 
         # get initialize flag
-        initialize = (self.get_node(self.initialize_path) or [None])[0] if self._INITIALIZE in nodes else None
+        initialize = (self.get_node(path + self._INITIALIZE) or [None])[0] if self._INITIALIZE in nodes else None
 
         # get global dynamic configuration
-        config = self.get_node(self.config_path, watch=self.cluster_watcher) if self._CONFIG in nodes else None
+        config = self.get_node(path + self._CONFIG, watch=self._watcher) if self._CONFIG in nodes else None
         config = config and ClusterConfig.from_node(config[1].version, config[0], config[1].mzxid)
 
         # get timeline history
-        history = self.get_node(self.history_path, watch=self.cluster_watcher) if self._HISTORY in nodes else None
+        history = self.get_node(path + self._HISTORY) if self._HISTORY in nodes else None
         history = history and TimelineHistory.from_node(history[1].mzxid, history[0])
 
         # get synchronization state
-        sync = self.get_node(self.sync_path, watch=self.cluster_watcher) if self._SYNC in nodes else None
+        sync = self.get_node(path + self._SYNC) if self._SYNC in nodes else None
         sync = SyncState.from_node(sync and sync[1].version, sync and sync[0])
 
         # get list of members
-        members = self.load_members() if self._MEMBERS[:-1] in nodes else []
+        members = self.load_members(path) if self._MEMBERS[:-1] in nodes else []
 
         # get leader
-        leader = self.get_node(self.leader_path) if self._LEADER in nodes else None
+        leader = self.get_node(path + self._LEADER, watch=self._watcher) if self._LEADER in nodes else None
         if leader:
-            client_id = self._client.client_id
-            if not self._ctl and leader[0] == self._name and client_id is not None \
-                    and client_id[0] != leader[1].ephemeralOwner:
-                logger.info('I am leader but not owner of the session. Removing leader node')
-                self._client.delete(self.leader_path)
-                leader = None
-
-            if leader:
-                member = Member(-1, leader[0], None, {})
-                member = ([m for m in members if m.name == leader[0]] or [member])[0]
-                leader = Leader(leader[1].version, leader[1].ephemeralOwner, member)
-                self._fetch_cluster = member.index == -1
+            member = Member(-1, leader[0], None, {})
+            member = ([m for m in members if m.name == leader[0]] or [member])[0]
+            leader = Leader(leader[1].version, leader[1].ephemeralOwner, member)
 
         # get last known leader lsn and slots
-        last_lsn, slots = self.get_status(leader)
+        status = self.get_status(path, leader)
 
         # failover key
-        failover = self.get_node(self.failover_path, watch=self.cluster_watcher) if self._FAILOVER in nodes else None
+        failover = self.get_node(path + self._FAILOVER) if self._FAILOVER in nodes else None
         failover = failover and Failover.from_node(failover[1].version, failover[0])
 
-        return Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots)
+        # get failsafe topology
+        failsafe = self.get_node(path + self._FAILSAFE) if self._FAILSAFE in nodes else None
+        try:
+            failsafe = json.loads(failsafe[0]) if failsafe else None
+        except Exception:
+            failsafe = None
 
-    def _load_cluster(self):
-        cluster = self.cluster
-        if self._fetch_cluster or cluster is None:
-            try:
-                cluster = self._client.retry(self._inner_load_cluster)
-            except Exception:
-                logger.exception('get_cluster')
-                self.cluster_watcher(None)
-                raise ZooKeeperError('ZooKeeper in not responding properly')
-        # The /status ZNode was updated or doesn't exist
-        elif self._fetch_status and not self._fetch_cluster or not cluster.last_lsn \
-                or cluster.has_permanent_logical_slots(self._name, False) and not cluster.slots:
-            # If current node is the leader just clear the event without fetching anything (we are updating the /status)
-            if cluster.leader and cluster.leader.name == self._name:
-                self.event.clear()
-            else:
-                try:
-                    last_lsn, slots = self.get_status(cluster.leader)
-                    self.event.clear()
-                    cluster = Cluster(cluster.initialize, cluster.config, cluster.leader, last_lsn,
-                                      cluster.members, cluster.failover, cluster.sync, cluster.history, slots)
-                except Exception:
-                    pass
-        return cluster
+        return Cluster(initialize, config, leader, status, members, failover, sync, history, failsafe)
 
-    def _bypass_caches(self):
-        self._fetch_cluster = True
+    def _mpp_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        """Load and build all PostgreSQL clusters from a single MPP cluster.
 
-    def _create(self, path, value, retry=False, ephemeral=False):
+        :param path: the path in DCS where to load Cluster(s) from.
+
+        :returns: all MPP groups as :class:`dict`, with group IDs as keys and :class:`Cluster` objects as values.
+        """
+        ret: Dict[int, Cluster] = {}
+        for node in self.get_children(path):
+            if self._mpp.group_re.match(node):
+                ret[int(node)] = self._postgresql_cluster_loader(path + node + '/')
+        return ret
+
+    def _load_cluster(
+            self, path: str, loader: Callable[[str], Union[Cluster, Dict[int, Cluster]]]
+    ) -> Union[Cluster, Dict[int, Cluster]]:
+        try:
+            return self._client.retry(loader, path)
+        except Exception:
+            logger.exception('get_cluster')
+            raise ZooKeeperError('ZooKeeper in not responding properly')
+
+    def _create(self, path: str, value: bytes, retry: bool = False, ephemeral: bool = False) -> bool:
         try:
             if retry:
                 self._client.retry(self._client.create, path, value, makepath=True, ephemeral=ephemeral)
@@ -324,66 +297,74 @@ class ZooKeeper(AbstractDCS):
             logger.exception('Failed to create %s', path)
         return False
 
-    def attempt_to_acquire_leader(self, permanent=False):
-        ret = self._create(self.leader_path, self._name.encode('utf-8'), retry=True, ephemeral=not permanent)
-        if not ret:
-            logger.info('Could not take out TTL lock')
-        return ret
+    def attempt_to_acquire_leader(self) -> bool:
+        try:
+            self._client.retry(self._client.create, self.leader_path, self._name.encode('utf-8'),
+                               makepath=True, ephemeral=True)
+            return True
+        except (ConnectionClosedError, RetryFailedError) as e:
+            raise ZooKeeperError(e)
+        except Exception as e:
+            if not isinstance(e, NodeExistsError):
+                logger.error('Failed to create %s: %r', self.leader_path, e)
+        logger.info('Could not take out TTL lock')
+        return False
 
-    def _set_or_create(self, key, value, index=None, retry=False, do_not_create_empty=False):
-        value = value.encode('utf-8')
+    def _set_or_create(self, key: str, value: str, version: Optional[int] = None,
+                       retry: bool = False, do_not_create_empty: bool = False) -> Union[int, bool]:
+        value_bytes = value.encode('utf-8')
         try:
             if retry:
-                self._client.retry(self._client.set, key, value, version=index or -1)
+                ret = self._client.retry(self._client.set, key, value_bytes, version=version or -1)
             else:
-                self._client.set_async(key, value, version=index or -1).get(timeout=1)
-            return True
+                ret = self._client.set_async(key, value_bytes, version=version or -1).get(timeout=1)
+            return ret.version
         except NoNodeError:
-            if do_not_create_empty and not value:
+            if do_not_create_empty and not value_bytes:
                 return True
-            elif index is None:
-                return self._create(key, value, retry)
+            elif version is None:
+                if self._create(key, value_bytes, retry):
+                    return 0
             else:
                 return False
         except Exception:
             logger.exception('Failed to update %s', key)
         return False
 
-    def set_failover_value(self, value, index=None):
-        return self._set_or_create(self.failover_path, value, index)
+    def set_failover_value(self, value: str, version: Optional[int] = None) -> bool:
+        return self._set_or_create(self.failover_path, value, version) is not False
 
-    def set_config_value(self, value, index=None):
-        return self._set_or_create(self.config_path, value, index, retry=True)
+    def set_config_value(self, value: str, version: Optional[int] = None) -> bool:
+        return self._set_or_create(self.config_path, value, version, retry=True) is not False
 
-    def initialize(self, create_new=True, sysid=""):
-        sysid = sysid.encode('utf-8')
-        return self._create(self.initialize_path, sysid, retry=True) if create_new \
-            else self._client.retry(self._client.set, self.initialize_path, sysid)
+    def initialize(self, create_new: bool = True, sysid: str = "") -> bool:
+        sysid_bytes = sysid.encode('utf-8')
+        return self._create(self.initialize_path, sysid_bytes, retry=True) if create_new \
+            else self._client.retry(self._client.set, self.initialize_path, sysid_bytes)
 
-    def touch_member(self, data, permanent=False):
+    def touch_member(self, data: Dict[str, Any]) -> bool:
         cluster = self.cluster
         member = cluster and cluster.get_member(self._name, fallback_to_leader=False)
         member_data = self.__last_member_data or member and member.data
-        if member and (self._client.client_id is not None and member.session != self._client.client_id[0] or
-                       not (deep_compare(member_data.get('tags', {}), data.get('tags', {})) and
-                            member_data.get('version') == data.get('version') and
-                            member_data.get('checkpoint_after_promote') == data.get('checkpoint_after_promote'))):
-            try:
-                self._client.delete_async(self.member_path).get(timeout=1)
-            except NoNodeError:
-                pass
-            except Exception:
-                return False
-            member = None
+        if member and member_data:
+            # We want delete the member ZNode if our session doesn't match with session id on our member key
+            if self._client.client_id is not None and member.session != self._client.client_id[0]:
+                logger.warning('Recreating the member ZNode due to ownership mismatch')
+                try:
+                    self._client.delete_async(self.member_path).get(timeout=1)
+                except NoNodeError:
+                    pass
+                except Exception:
+                    return False
+                member = None
 
         encoded_data = json.dumps(data, separators=(',', ':')).encode('utf-8')
-        if member:
+        if member and member_data:
             if deep_compare(data, member_data):
                 return True
         else:
             try:
-                self._client.create_async(self.member_path, encoded_data, makepath=True,
-                                          ephemeral=not permanent).get(timeout=1)
+                self._client.create_async(self.member_path, encoded_data, makepath=True, ephemeral=True).get(timeout=1)
                 self.__last_member_data = data
                 return True
             except Exception as e:
@@ -399,50 +380,78 @@ class ZooKeeper(AbstractDCS):
 
         return False
 
-    def take_leader(self):
+    def take_leader(self) -> bool:
         return self.attempt_to_acquire_leader()
 
-    def _write_leader_optime(self, last_lsn):
-        return self._set_or_create(self.leader_optime_path, last_lsn)
+    def _write_leader_optime(self, last_lsn: str) -> bool:
+        return self._set_or_create(self.leader_optime_path, last_lsn) is not False
 
-    def _write_status(self, value):
-        return self._set_or_create(self.status_path, value)
+    def _write_status(self, value: str) -> bool:
+        return self._set_or_create(self.status_path, value) is not False
 
-    def _update_leader(self):
+    def _write_failsafe(self, value: str) -> bool:
+        return self._set_or_create(self.failsafe_path, value) is not False
+
+    def _update_leader(self, leader: Leader) -> bool:
+        if self._client.client_id and self._client.client_id[0] != leader.session:
+            logger.warning('Recreating the leader ZNode due to ownership mismatch')
+            try:
+                self._client.retry(self._client.delete, self.leader_path)
+            except NoNodeError:
+                pass
+            except (ConnectionClosedError, RetryFailedError) as e:
+                raise ZooKeeperError(e)
+            except Exception as e:
+                logger.error('Failed to remove %s: %r', self.leader_path, e)
+                return False
+
+            try:
+                self._client.retry(self._client.create, self.leader_path,
+                                   self._name.encode('utf-8'), makepath=True, ephemeral=True)
+            except (ConnectionClosedError, RetryFailedError) as e:
+                raise ZooKeeperError(e)
+            except Exception as e:
+                logger.error('Failed to create %s: %r', self.leader_path, e)
+                return False
         return True
 
-    def _delete_leader(self):
+    def _delete_leader(self, leader: Leader) -> bool:
         self._client.restart()
         return True
 
-    def _cancel_initialization(self):
+    def _cancel_initialization(self) -> None:
         node = self.get_node(self.initialize_path)
         if node:
             self._client.delete(self.initialize_path, version=node[1].version)
 
-    def cancel_initialization(self):
+    def cancel_initialization(self) -> bool:
         try:
             self._client.retry(self._cancel_initialization)
+            return True
         except Exception:
             logger.exception("Unable to delete initialize key")
+        return False
 
-    def delete_cluster(self):
+    def delete_cluster(self) -> bool:
         try:
             return self._client.retry(self._client.delete, self.client_path(''), recursive=True)
         except NoNodeError:
             return True
 
-    def set_history_value(self, value):
-        return self._set_or_create(self.history_path, value)
+    def set_history_value(self, value: str) -> bool:
+        return self._set_or_create(self.history_path, value) is not False
 
-    def set_sync_state_value(self, value, index=None):
-        return self._set_or_create(self.sync_path, value, index, retry=True, do_not_create_empty=True)
+    def set_sync_state_value(self, value: str, version: Optional[int] = None) -> Union[int, bool]:
+        return self._set_or_create(self.sync_path, value, version, retry=True, do_not_create_empty=True)
 
-    def delete_sync_state(self, index=None):
-        return self.set_sync_state_value("{}", index)
+    def delete_sync_state(self, version: Optional[int] = None) -> bool:
+        return self.set_sync_state_value("{}", version) is not False
 
-    def watch(self, leader_index, timeout):
-        ret = super(ZooKeeper, self).watch(leader_index, timeout + 0.5)
-        if ret and not self._fetch_status:
-            self._fetch_cluster = True
-        return ret or self._fetch_cluster
+    def watch(self, leader_version: Optional[int], timeout: float) -> bool:
+        if leader_version:
+            timeout += 0.5
+
+        try:
+            return super(ZooKeeper, self).watch(leader_version, timeout)
+        finally:
+            self.event.clear()

patroni/dynamic_loader.py

@@ -0,0 +1,96 @@
+"""Helper functions to search for implementations of specific abstract interface in a package."""
+import importlib
+import inspect
+import logging
+import os
+import pkgutil
+import sys
+from types import ModuleType
+
+from typing import Any, Dict, Iterator, List, Optional, Set, Tuple, TYPE_CHECKING, Type, TypeVar, Union
+
+if TYPE_CHECKING:  # pragma: no cover
+    from .config import Config
+
+logger = logging.getLogger(__name__)
+
+
+def iter_modules(package: str) -> List[str]:
+    """Get names of modules from *package*, depending on execution environment.
+
+    .. note::
+        If being packaged with PyInstaller, modules aren't discoverable dynamically by scanning source directory because
+        :class:`importlib.machinery.FrozenImporter` doesn't implement :func:`iter_modules`. But it is still possible to
+        find all potential modules by iterating through ``toc``, which contains list of all "frozen" resources.
+
+    :param package: a package name to search modules in, e.g. ``patroni.dcs``.
+
+    :returns: list of known module names with absolute python module path namespace, e.g. ``patroni.dcs.etcd``.
+    """
+    module_prefix = package + '.'
+
+    if getattr(sys, 'frozen', False):
+        toc: Set[str] = set()
+        # dirname may contain a few dots, which causes pkgutil.iter_importers()
+        # to misinterpret the path as a package name. This can be avoided
+        # altogether by not passing a path at all, because PyInstaller's
+        # FrozenImporter is a singleton and registered as top-level finder.
+        for importer in pkgutil.iter_importers():
+            if hasattr(importer, 'toc'):
+                toc |= getattr(importer, 'toc')
+        dots = module_prefix.count('.')  # search for modules only on the same level
+        return [module for module in toc if module.startswith(module_prefix) and module.count('.') == dots]
+
+    # here we are making an assumption that the package which is calling this function is already imported
+    pkg_file = sys.modules[package].__file__
+    if TYPE_CHECKING:  # pragma: no cover
+        assert isinstance(pkg_file, str)
+    return [name for _, name, is_pkg in pkgutil.iter_modules([os.path.dirname(pkg_file)], module_prefix) if not is_pkg]
+
+
+ClassType = TypeVar("ClassType")
+
+
+def find_class_in_module(module: ModuleType, cls_type: Type[ClassType]) -> Optional[Type[ClassType]]:
+    """Try to find the implementation of *cls_type* class interface in *module* matching the *module* name.
+
+    :param module: imported module.
+    :param cls_type: a class type we are looking for.
+
+    :returns: class with a name matching the name of *module* that implements *cls_type* or ``None`` if not found.
+    """
+    module_name = module.__name__.rpartition('.')[2]
+    return next(
+        (obj for obj_name, obj in module.__dict__.items()
+         if (obj_name.lower() == module_name
+             and inspect.isclass(obj) and issubclass(obj, cls_type))),
+        None)
+
+
+def iter_classes(
+        package: str, cls_type: Type[ClassType],
+        config: Optional[Union['Config', Dict[str, Any]]] = None
+) -> Iterator[Tuple[str, Type[ClassType]]]:
+    """Attempt to import modules and find implementations of *cls_type* that are present in the given configuration.
+
+    .. note::
+            If a module successfully imports we can assume that all its requirements are installed.
+
+    :param package: a package name to search modules in, e.g. ``patroni.dcs``.
+    :param cls_type: a class type we are looking for.
+    :param config: configuration information with possible module names as keys. If given, only attempt to import
+                   modules defined in the configuration. Else, if ``None``, attempt to import any supported module.
+
+    :yields: a tuple containing the module ``name`` and the imported class object.
+    """
+    for mod_name in iter_modules(package):
+        name = mod_name.rpartition('.')[2]
+        if config is None or name in config:
+            try:
+                module = importlib.import_module(mod_name)
+                module_cls = find_class_in_module(module, cls_type)
+                if module_cls:
+                    yield name, module_cls
+            except ImportError:
+                logger.log(logging.DEBUG if config is not None else logging.INFO,
+                           'Failed to import %s', mod_name)

patroni/exceptions.py

@@ -1,37 +1,55 @@
+"""Implement high-level Patroni exceptions.
+
+More specific exceptions can be found in other modules, as subclasses of any exception defined in this module.
+"""
+from typing import Any
+
+
 class PatroniException(Exception):
+    """Parent class for all kind of Patroni exceptions.
 
-    """Parent class for all kind of exceptions related to selected distributed configuration store"""
+    :ivar value: description of the exception.
+    """
 
-    def __init__(self, value):
+    def __init__(self, value: Any) -> None:
+        """Create a new instance of :class:`PatroniException` with the given description.
+
+        :param value: description of the exception.
+        """
         self.value = value
 
-    def __str__(self):
-        """
-        >>> str(PatroniException('foo'))
-        "'foo'"
-        """
-        return repr(self.value)
-
 
 class PatroniFatalException(PatroniException):
+    """Catastrophic exception that prevents Patroni from performing its job."""
+
     pass
 
 
 class PostgresException(PatroniException):
+    """Any exception related with Postgres management."""
+
     pass
 
 
 class DCSError(PatroniException):
+    """Parent class for all kind of DCS related exceptions."""
+
     pass
 
 
 class PostgresConnectionException(PostgresException):
+    """Any problem faced while connecting to a Postgres instance."""
+
     pass
 
 
 class WatchdogError(PatroniException):
+    """Any problem faced while managing a watchdog device."""
+
     pass
 
 
 class ConfigParseError(PatroniException):
+    """Any issue identified while loading or validating the Patroni configuration."""
+
     pass

patroni/file_perm.py

@@ -0,0 +1,95 @@
+"""Helper object that helps with figuring out file and directory permissions based on permissions of PGDATA.
+
+:var logger: logger of this module.
+:var pg_perm: instance of the :class:`__FilePermissions` object.
+"""
+import logging
+import os
+import stat
+
+logger = logging.getLogger(__name__)
+
+
+class __FilePermissions:
+    """Helper class for managing permissions of directories and files under PGDATA.
+
+    Execute :meth:`set_permissions_from_data_directory` to figure out which permissions should be used for files and
+    directories under PGDATA based on permissions of PGDATA root directory.
+    """
+
+    # Mode mask for data directory permissions that only allows the owner to
+    # read/write directories and files -- mask 077.
+    __PG_MODE_MASK_OWNER = stat.S_IRWXG | stat.S_IRWXO
+
+    # Mode mask for data directory permissions that also allows group read/execute -- mask 027.
+    __PG_MODE_MASK_GROUP = stat.S_IWGRP | stat.S_IRWXO
+
+    # Default mode for creating directories -- mode 700.
+    __PG_DIR_MODE_OWNER = stat.S_IRWXU
+
+    # Mode for creating directories that allows group read/execute -- mode 750.
+    __PG_DIR_MODE_GROUP = stat.S_IRWXU | stat.S_IRGRP | stat.S_IXGRP
+
+    # Default mode for creating files -- mode 600.
+    __PG_FILE_MODE_OWNER = stat.S_IRUSR | stat.S_IWUSR
+
+    # Mode for creating files that allows group read -- mode 640.
+    __PG_FILE_MODE_GROUP = stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP
+
+    def __init__(self) -> None:
+        """Create a :class:`__FilePermissions` object and set default permissions."""
+        self.__set_owner_permissions()
+        self.__set_umask()
+
+    def __set_umask(self) -> None:
+        """Set umask value based on calculations.
+
+        .. note::
+            Should only be called once either :meth:`__set_owner_permissions`
+            or :meth:`__set_group_permissions` has been executed.
+        """
+        try:
+            os.umask(self.__pg_mode_mask)
+        except Exception as e:
+            logger.error('Can not set umask to %03o: %r', self.__pg_mode_mask, e)
+
+    def __set_owner_permissions(self) -> None:
+        """Make directories/files accessible only by the owner."""
+        self.__pg_dir_create_mode = self.__PG_DIR_MODE_OWNER
+        self.__pg_file_create_mode = self.__PG_FILE_MODE_OWNER
+        self.__pg_mode_mask = self.__PG_MODE_MASK_OWNER
+
+    def __set_group_permissions(self) -> None:
+        """Make directories/files accessible by the owner and readable by group."""
+        self.__pg_dir_create_mode = self.__PG_DIR_MODE_GROUP
+        self.__pg_file_create_mode = self.__PG_FILE_MODE_GROUP
+        self.__pg_mode_mask = self.__PG_MODE_MASK_GROUP
+
+    def set_permissions_from_data_directory(self, data_dir: str) -> None:
+        """Set new permissions based on provided *data_dir*.
+
+        :param data_dir: reference to PGDATA to calculate permissions from.
+        """
+        try:
+            st = os.stat(data_dir)
+            if (st.st_mode & self.__PG_DIR_MODE_GROUP) == self.__PG_DIR_MODE_GROUP:
+                self.__set_group_permissions()
+            else:
+                self.__set_owner_permissions()
+        except Exception as e:
+            logger.error('Can not check permissions on %s: %r', data_dir, e)
+        else:
+            self.__set_umask()
+
+    @property
+    def dir_create_mode(self) -> int:
+        """Directory permissions."""
+        return self.__pg_dir_create_mode
+
+    @property
+    def file_create_mode(self) -> int:
+        """File permissions."""
+        return self.__pg_file_create_mode
+
+
+pg_perm = __FilePermissions()