Release v3.0.3 (#2719)

* Bump version
* Bump pyright version and fix newly reported issues
* Update release notes
* Fix typos, extend release process desc
* Add readthedocs configuration file v2
* Fix Dockerfile.citus files

.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

@@ -0,0 +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
 
 
@@ -18,7 +17,10 @@ def install_requirements(what):
     finally:
         sys.path = old_path
     requirements = ['mock>=2.0.0', 'flake8', 'pytest', 'pytest-cov'] if what == 'all' else ['behave']
-    requirements += ['psycopg2-binary', 'coverage']
+    requirements += ['coverage']
+    # try to split tests between psycopg2 and psycopg3
+    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()
         if r != '':
@@ -27,6 +29,7 @@ def install_requirements(what):
                 requirements.append(r)
 
     subprocess.call([sys.executable, '-m', 'pip', 'install', '--upgrade', 'pip'])
+    subprocess.call([sys.executable, '-m', 'pip', 'install', '--upgrade', 'wheel'])
     r = subprocess.call([sys.executable, '-m', 'pip', 'install'] + requirements)
     s = subprocess.call([sys.executable, '-m', 'pip', 'install', '--upgrade', 'setuptools'])
     return s | r
@@ -42,10 +45,10 @@ def install_packages(what):
     packages['exhibitor'] = packages['zookeeper']
     packages = packages.get(what, [])
     ver = versions.get(what)
-    subprocess.call(['sudo', 'sed', '-i', 's/pgdg main.*$/pgdg main {0}/'.format(ver),
-                     '/etc/apt/sources.list.d/pgdg.list'])
+    if float(ver) >= 15:
+        packages += ['postgresql-{0}-citus-11.2'.format(ver)]
     subprocess.call(['sudo', 'apt-get', 'update', '-y'])
-    return subprocess.call(['sudo', 'apt-get', 'install', '-y', 'postgresql-' + ver, 'expect-dev', 'wget'] + packages)
+    return subprocess.call(['sudo', 'apt-get', 'install', '-y', 'postgresql-' + ver, 'expect-dev'] + packages)
 
 
 def get_file(url, name):
@@ -82,8 +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):
@@ -95,7 +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'
@@ -107,59 +110,17 @@ def install_etcd():
 
 
 def install_postgres():
-    version = os.environ.get('PGVERSION', '12.1-1')
+    version = os.environ.get('PGVERSION', '15.1-1')
     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():
@@ -168,8 +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': '14'}
+versions = {'etcd': '9.6', 'etcd3': '14', 'consul': '13', 'exhibitor': '12', 'raft': '11', 'kubernetes': '15'}

.github/workflows/release.yaml

@@ -0,0 +1,41 @@
+name: Publish Patroni distributions to PyPI and TestPyPI
+on:
+  push:
+    tags:
+      - 'v[0-9]+.[0-9]+.[0-9]+'
+  release:
+    types:
+      - published
+jobs:
+  build-n-publish:
+    name: Build and publish Patroni distributions to PyPI and TestPyPI
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+
+    - name: Set up Python 3.9
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.9
+
+    - name: Install dependencies
+      run: python .github/workflows/install_deps.py
+
+    - name: Run tests and flake8
+      run: python .github/workflows/run_tests.py
+
+    - name: Build a binary wheel and a source tarball
+      run: python setup.py sdist bdist_wheel
+
+    - name: Publish distribution to Test PyPI
+      if: github.event_name == 'push'
+      uses: pypa/[email protected]
+      with:
+        password: ${{ secrets.TEST_PYPI_API_TOKEN }}
+        repository_url: https://test.pypi.org/legacy/
+
+    - name: Publish distribution to PyPI
+      if: github.event_name == 'release'
+      uses: pypa/[email protected]
+      with:
+        password: ${{ secrets.PYPI_API_TOKEN }}

.github/workflows/run_tests.py

@@ -27,23 +27,21 @@ def main():
 
         version = versions.get(what)
         path = '/usr/lib/postgresql/{0}/bin:.'.format(version)
-        unbuffer = ['timeout', '600', 'unbuffer']
-        args = ['--tags=-skip'] if what == 'etcd' else []
+        unbuffer = ['timeout', '900', 'unbuffer']
     else:
-        path = os.path.abspath(os.path.join('pgsql', 'bin'))
         if sys.platform == 'darwin':
-            path += ':.'
-        args = unbuffer = []
+            version = os.environ.get('PGVERSION', '15.1-1')
+            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'] + args, 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 +5,10 @@ on:
   push:
     branches:
     - master
-    tags:
-    - v.*
+
+env:
+  CODACY_PROJECT_TOKEN: ${{ secrets.CODACY_PROJECT_TOKEN }}
+  SECRETS_AVAILABLE: ${{ secrets.CODACY_PROJECT_TOKEN != '' }}
 
 jobs:
   unit:
@@ -17,39 +19,10 @@ jobs:
         os: [ubuntu, windows, macos]
 
     steps:
-    - uses: actions/checkout@v1
-    - name: Set up Python 2.7
-      uses: actions/setup-python@v2
-      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 3.5
-      uses: actions/setup-python@v2
-      with:
-        python-version: 3.5
-    - 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 3.6
-      uses: actions/setup-python@v2
-      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
+    - uses: actions/checkout@v3
 
     - name: Set up Python 3.7
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: 3.7
     - name: Install dependencies
@@ -58,7 +31,7 @@ jobs:
       run: python .github/workflows/run_tests.py
 
     - name: Set up Python 3.8
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: 3.8
     - name: Install dependencies
@@ -67,7 +40,7 @@ jobs:
       run: python .github/workflows/run_tests.py
 
     - name: Set up Python 3.9
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: 3.9
     - name: Install dependencies
@@ -75,6 +48,24 @@ jobs:
     - name: Run tests and flake8
       run: python .github/workflows/run_tests.py
 
+    - name: Set up Python 3.10
+      uses: actions/setup-python@v4
+      with:
+        python-version: '3.10'
+    - 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 3.11
+      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
 
@@ -88,90 +79,98 @@ jobs:
         GITHUB_TOKEN: ${{ secrets.github_token }}
       run: python -m coveralls --service=github
 
-    - name: Run codacy-coverage-reporter
-      uses: codacy/codacy-coverage-reporter-action@master
-      env:
-        SECRETS_AVAILABLE: ${{ secrets.CODACY_PROJECT_TOKEN != '' }}
-      with:
-        project-token: ${{ secrets.CODACY_PROJECT_TOKEN }}
-        coverage-reports: coverage.xml
-      if: ${{ matrix.os == 'ubuntu' && env.SECRETS_AVAILABLE == 'true' }}
-
   behave:
     runs-on: ${{ matrix.os }}-latest
     env:
       DCS: ${{ matrix.dcs }}
-      ETCDVERSION: 3.3.13
+      ETCDVERSION: 3.4.23
+      PGVERSION: 15.1-1  # for windows and macos
     strategy:
       fail-fast: false
       matrix:
         os: [ubuntu]
-        python-version: [2.7, 3.5, 3.8]
+        python-version: [3.7, '3.10']
         dcs: [etcd, etcd3, consul, exhibitor, kubernetes, raft]
+        include:
+        - os: macos
+          python-version: 3.8
+          dcs: raft
+        - os: macos
+          python-version: 3.9
+          dcs: etcd
+        - os: macos
+          python-version: 3.11
+          dcs: etcd3
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v3
     - name: Set up Python
-      uses: actions/setup-python@v2
+      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/ $(lsb_release -cs) main" > /etc/apt/sources.list.d/citusdata_community.list'
+        sudo sh -c 'wget -qO - https://packagecloud.io/citusdata/community/gpgkey | gpg --dearmor > /etc/apt/trusted.gpg.d/citusdata_community.gpg'
+      if: matrix.os == 'ubuntu'
     - name: Install dependencies
       run: python .github/workflows/install_deps.py
     - name: Run behave tests
       run: python .github/workflows/run_tests.py
-    - uses: actions/setup-python@v2
+    - name: Upload logs if behave failed
+      uses: actions/upload-artifact@v3
+      if: failure()
       with:
-        python-version: 3.9
-    - name: Install coveralls
-      run: python -m pip install coveralls
-    - name: Upload Coverage
-      env:
-        COVERALLS_FLAG_NAME: behave-${{ matrix.os }}-${{ matrix.dcs }}-${{ matrix.python-version }}
-        COVERALLS_PARALLEL: 'true'
-        GITHUB_TOKEN: ${{ secrets.github_token }}
-      run: python -m coveralls --service=github
-
-  behavem:
-    runs-on: ${{ matrix.os }}-latest
-    env:
-      DCS: ${{ matrix.dcs }}
-      ETCDVERSION: 3.3.13
-      PGVERSION: 12.1-1  # for windows and macos
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [macos]  #, windows]
-        python-version: [3.7]
-        dcs: [etcd, etcd3, raft]
-
-    steps:
-    - uses: actions/checkout@v1
-    - name: Set up Python
-      uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      run: python .github/workflows/install_deps.py
-    - name: Run behave tests
-      run: python .github/workflows/run_tests.py
-    - name: Install coveralls
-      run: python -m pip install coveralls
-    - name: Upload Coverage
-      env:
-        COVERALLS_FLAG_NAME: behave-${{ 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, behavem]
+    needs: unit
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/setup-python@v2
+    - uses: actions/setup-python@v4
     - run: python -m pip install coveralls
     - 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: 1.1.315

.readthedocs.yaml

@@ -0,0 +1,21 @@
+# .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

CODEOWNERS

@@ -0,0 +1,2 @@
+# global owners
+*        @CyberDem0n @hughcapet

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=10
+ARG PG_MAJOR=15
 ARG COMPRESS=false
 ARG PGHOME=/home/postgres
 ARG PGDATA=$PGHOME/data
@@ -43,24 +43,36 @@ 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 \
+                git make \
     && apt-get autoremove -y \
     && apt-get clean -y \
     && rm -rf /var/lib/apt/lists/* \
@@ -90,7 +102,7 @@ RUN set -ex \
     && 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 +111,10 @@ 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 $libs) | sort -u | sed 's/^\///' > /exclude \
         && find /etc/alternatives -xtype l -delete \
         && save_dirs="usr lib var bin sbin etc/ssl etc/init.d etc/alternatives etc/apt" \
@@ -117,7 +131,7 @@ RUN if [ "$COMPRESS" = "true" ]; then \
 FROM scratch
 COPY --from=builder / /
 
-LABEL maintainer="Alexander Kukushkin <alexander.kukushkin@zalando.de>"
+LABEL maintainer="Alexander Kukushkin <akukushkin@microsoft.com>"
 
 ARG PG_MAJOR
 ARG COMPRESS
@@ -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=15
+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 --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-11.3; \
+    fi \
+    && pip3 install dumb-init \
+\
+    # 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 libpython2.7-stdlib libpython2.7-minimal \
+                postgresql-server-dev-$PG_MAJOR git gcc make autoconf \
+                libc6-dev flex libicu-dev libkrb5-dev liblz4-dev \
+                libpam0g-dev libreadline-dev libselinux1-dev libssl-dev libxslt1-dev libzstd-dev uuid-dev \
+    && apt-get autoremove -y \
+    && apt-get clean -y \
+    && rm -rf /var/lib/apt/lists/* \
+        /root/.cache \
+        /var/cache/debconf/* \
+        /etc/rc?.d \
+        /etc/systemd \
+        /docker-entrypoint* \
+        /sbin/pam* \
+        /sbin/swap* \
+        /sbin/unix* \
+        /usr/local/bin/gosu \
+        /usr/sbin/[acgipr]* \
+        /usr/sbin/*user* \
+        /usr/share/doc* \
+        /usr/share/man \
+        /usr/share/info \
+        /usr/share/i18n/locales/translit_hangul \
+        /usr/share/locale/?? \
+        /usr/share/locale/??_?? \
+        /usr/share/postgresql/*/man \
+        /usr/share/postgresql-common/pg_wrapper \
+        /usr/share/vim/vim80/doc \
+        /usr/share/vim/vim80/lang \
+        /usr/share/vim/vim80/tutor \
+#        /var/lib/dpkg/info/* \
+    && find /usr/bin -xtype l -delete \
+    && find /var/log -type f -exec truncate --size 0 {} \; \
+    && find /usr/lib/python3/dist-packages -name '*test*' | xargs rm -fr \
+    && find /lib/$(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
+
+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"]

MAINTAINERS

@@ -1,3 +1,2 @@
-Alexander Kukushkin <alexander.kukushkin@zalando.de>
-Feike Steenbergen <feike.steenbergen@zalando.de>
-Oleksii Kliukin <[email protected]>
+Alexander Kukushkin <akukushkin@microsoft.com>
+Polina Bungina <polina.bungina@zalando.de>

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 13.
+Currently supported PostgreSQL versions: 9.3 to 15.
+
+**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
@@ -61,7 +63,7 @@ To install requirements on a Mac, run the following:
 
     brew install postgresql etcd haproxy libyaml python
 
-**Psycopg2**
+**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.
@@ -88,6 +90,12 @@ There are a few options available:
 
     pip install psycopg2>=2.5.4
 
+4. Use psycopg 3.0 instead of psycopg2
+
+::
+
+    pip install psycopg[binary]
+
 **General installation for pip**
 
 Patroni can be installed with pip:
@@ -111,7 +119,7 @@ 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
 
 For example, the command in order to install Patroni together with dependencies for Etcd as a DCS and AWS callbacks is:
 

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 +1,140 @@
+# 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:
+            ETCDCTL_API: 3
+            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_API: 3
+            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
@@ -15,6 +22,7 @@ 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
@@ -32,7 +40,7 @@ services:
         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
 
@@ -12,7 +12,10 @@ 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:
 
@@ -92,7 +95,8 @@ Example session:
     b2e169fcb8a34028: name=etcd1 peerURLs=http://etcd1:2380 clientURLs=http://etcd1:2379 isLeader=false
     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))
     Type "help" for help.
@@ -105,7 +109,7 @@ Example session:
 
     localhost/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))
     Type "help" for help.
@@ -115,3 +119,188 @@ Example session:
     ───────────────────
      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
+    Creating demo-work2-1 ... done
+    Creating demo-work1-1 ... done
+    Creating demo-etcd2   ... done
+    Creating demo-etcd1   ... done
+    Creating demo-coord3  ... done
+    Creating demo-etcd3   ... done
+    Creating demo-coord1  ... done
+    Creating demo-haproxy ... done
+    Creating demo-work2-2 ... done
+    Creating demo-coord2  ... done
+    Creating demo-work1-2 ... done
+
+    $ docker ps
+    CONTAINER ID   IMAGE                  COMMAND                  CREATED         STATUS         PORTS                              NAMES
+    852d8885a612   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 3 seconds                                      demo-coord3
+    cdd692f947ab   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 3 seconds                                      demo-work1-2
+    9f4e340b36da   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 3 seconds                                      demo-etcd3
+    d69c129a960a   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 4 seconds                                      demo-etcd1
+    c5849689b8cd   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 4 seconds                                      demo-coord1
+    c9d72bd6217d   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 3 seconds                                      demo-work2-1
+    24b1b43efa05   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 4 seconds                                      demo-coord2
+    cb0cc2b4ca0a   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 3 seconds                                      demo-work2-2
+    9796c6b8aad5   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 5 seconds                                      demo-work1-1
+    8baccd74dcae   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 4 seconds                                      demo-etcd2
+    353ec62a0187   patroni-citus          "/bin/sh /entrypoint…"   6 seconds ago   Up 4 seconds   0.0.0.0:5000-5001->5000-5001/tcp   demo-haproxy
+
+    $ docker logs demo-coord1
+    2023-01-05 15:09:31,295 INFO: Selected new etcd server http://172.27.0.4:2379
+    2023-01-05 15:09:31,388 INFO: Lock owner: None; I am coord1
+    2023-01-05 15:09:31,501 INFO: trying to bootstrap a new cluster
+    ...
+    2023-01-05 15:09:45,096 INFO: postmaster pid=39
+    localhost:5432 - no response
+    2023-01-05 15:09:45.137 UTC [39] LOG:  starting PostgreSQL 15.1 (Debian 15.1-1.pgdg110+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit
+    2023-01-05 15:09:45.137 UTC [39] LOG:  listening on IPv4 address "0.0.0.0", port 5432
+    2023-01-05 15:09:45.152 UTC [39] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
+    2023-01-05 15:09:45.177 UTC [43] LOG:  database system was shut down at 2023-01-05 15:09:32 UTC
+    2023-01-05 15:09:45.193 UTC [39] LOG:  database system is ready to accept connections
+    localhost:5432 - accepting connections
+    localhost:5432 - accepting connections
+    2023-01-05 15:09:46,139 INFO: establishing a new patroni connection to the postgres cluster
+    2023-01-05 15:09:46,208 INFO: running post_bootstrap
+    2023-01-05 15:09:47.209 UTC [55] LOG:  starting maintenance daemon on database 16386 user 10
+    2023-01-05 15:09:47.209 UTC [55] CONTEXT:  Citus maintenance daemon for database 16386 user 10
+    2023-01-05 15:09:47,215 WARNING: Could not activate Linux watchdog device: "Can't open watchdog device: [Errno 2] No such file or directory: '/dev/watchdog'"
+    2023-01-05 15:09:47.446 UTC [41] LOG:  checkpoint starting: immediate force wait
+    2023-01-05 15:09:47,466 INFO: initialized a new cluster
+    2023-01-05 15:09:47,594 DEBUG: query(SELECT nodeid, groupid, nodename, nodeport, noderole FROM pg_catalog.pg_dist_node WHERE noderole = 'primary', ())
+    2023-01-05 15:09:47,594 INFO: establishing a new patroni connection to the postgres cluster
+    2023-01-05 15:09:47,467 INFO: Lock owner: coord1; I am coord1
+    2023-01-05 15:09:47,613 DEBUG: query(SELECT pg_catalog.citus_set_coordinator_host(%s, %s, 'primary', 'default'), ('172.27.0.6', 5432))
+    2023-01-05 15:09:47,924 INFO: no action. I am (coord1), the leader with the lock
+    2023-01-05 15:09:51.282 UTC [41] LOG:  checkpoint complete: wrote 1086 buffers (53.0%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.029 s, sync=3.746 s, total=3.837 s; sync files=280, longest=0.028 s, average=0.014 s; distance=8965 kB, estimate=8965 kB
+    2023-01-05 15:09:51.283 UTC [41] LOG:  checkpoint starting: immediate force wait
+    2023-01-05 15:09:51.495 UTC [41] LOG:  checkpoint complete: wrote 18 buffers (0.9%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.044 s, sync=0.091 s, total=0.212 s; sync files=15, longest=0.015 s, average=0.007 s; distance=67 kB, estimate=8076 kB
+    2023-01-05 15:09:57,467 INFO: Lock owner: coord1; I am coord1
+    2023-01-05 15:09:57,569 INFO: Assigning synchronous standby status to ['coord3']
+    server signaled
+    2023-01-05 15:09:57.574 UTC [39] LOG:  received SIGHUP, reloading configuration files
+    2023-01-05 15:09:57.580 UTC [39] LOG:  parameter "synchronous_standby_names" changed to "coord3"
+    2023-01-05 15:09:59,637 INFO: Synchronous standby status assigned to ['coord3']
+    2023-01-05 15:09:59,638 DEBUG: query(SELECT pg_catalog.citus_add_node(%s, %s, %s, 'primary', 'default'), ('172.27.0.2', 5432, 1))
+    2023-01-05 15:09:59.690 UTC [67] LOG:  standby "coord3" is now a synchronous standby with priority 1
+    2023-01-05 15:09:59.690 UTC [67] STATEMENT:  START_REPLICATION SLOT "coord3" 0/3000000 TIMELINE 1
+    2023-01-05 15:09:59,694 INFO: no action. I am (coord1), the leader with the lock
+    2023-01-05 15:09:59,704 DEBUG: query(SELECT pg_catalog.citus_add_node(%s, %s, %s, 'primary', 'default'), ('172.27.0.8', 5432, 2))
+    2023-01-05 15:10:07,625 INFO: no action. I am (coord1), the leader with the lock
+    2023-01-05 15:10:17,579 INFO: no action. I am (coord1), the leader with the lock
+
+    $ docker exec -ti demo-haproxy bash
+    postgres@haproxy:~$ etcdctl member list
+    1bab629f01fa9065, started, etcd3, http://etcd3:2380, http://172.27.0.10:2379
+    8ecb6af518d241cc, started, etcd2, http://etcd2:2380, http://172.27.0.4:2379
+    b2e169fcb8a34028, started, etcd1, http://etcd1:2380, http://172.27.0.7:2379
+
+    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 (15.1 (Debian 15.1-1.pgdg110+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 | 172.27.0.6 |     5432 | default  | t           | t        | primary  | default     | t              | f
+          2 |       1 | 172.27.0.2 |     5432 | default  | t           | t        | primary  | default     | t              | t
+          3 |       2 | 172.27.0.8 |     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  | 172.27.0.6  | Leader       | running |  1 |           |
+    |     0 | coord2  | 172.27.0.5  | Replica      | running |  1 |         0 |
+    |     0 | coord3  | 172.27.0.9  | Sync Standby | running |  1 |         0 |
+    |     1 | work1-1 | 172.27.0.2  | Leader       | running |  1 |           |
+    |     1 | work1-2 | 172.27.0.12 | Sync Standby | running |  1 |         0 |
+    |     2 | work2-1 | 172.27.0.11 | Sync Standby | running |  1 |         0 |
+    |     2 | work2-2 | 172.27.0.8  | Leader       | running |  1 |           |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+
+    postgres@haproxy:~$ patronictl switchover --group 2 --force
+    Current cluster topology
+    + Citus cluster: demo (group: 2, 7185185529556963355) +-----------+
+    | Member  | Host        | Role         | State   | TL | Lag in MB |
+    +---------+-------------+--------------+---------+----+-----------+
+    | work2-1 | 172.27.0.11 | Sync Standby | running |  1 |         0 |
+    | work2-2 | 172.27.0.8  | Leader       | running |  1 |           |
+    +---------+-------------+--------------+---------+----+-----------+
+    2023-01-05 15:29:29.54204 Successfully switched over to "work2-1"
+    + Citus cluster: demo (group: 2, 7185185529556963355) -------+
+    | Member  | Host        | Role    | State   | TL | Lag in MB |
+    +---------+-------------+---------+---------+----+-----------+
+    | work2-1 | 172.27.0.11 | Leader  | running |  1 |           |
+    | work2-2 | 172.27.0.8  | Replica | stopped |    |   unknown |
+    +---------+-------------+---------+---------+----+-----------+
+
+    postgres@haproxy:~$ patronictl list
+    + Citus cluster: demo ----------+--------------+---------+----+-----------+
+    | Group | Member  | Host        | Role         | State   | TL | Lag in MB |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+    |     0 | coord1  | 172.27.0.6  | Leader       | running |  1 |           |
+    |     0 | coord2  | 172.27.0.5  | Replica      | running |  1 |         0 |
+    |     0 | coord3  | 172.27.0.9  | Sync Standby | running |  1 |         0 |
+    |     1 | work1-1 | 172.27.0.2  | Leader       | running |  1 |           |
+    |     1 | work1-2 | 172.27.0.12 | Sync Standby | running |  1 |         0 |
+    |     2 | work2-1 | 172.27.0.11 | Leader       | running |  2 |           |
+    |     2 | work2-2 | 172.27.0.8  | Sync Standby | running |  2 |         0 |
+    +-------+---------+-------------+--------------+---------+----+-----------+
+
+    postgres@haproxy:~$ psql -h localhost -p 5000 -U postgres -d citus
+    Password for user postgres: postgres
+    psql (15.1 (Debian 15.1-1.pgdg110+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 | 172.27.0.6  |     5432 | default  | t           | t        | primary  | default     | t              | f
+          3 |       2 | 172.27.0.11 |     5432 | default  | t           | t        | primary  | default     | t              | t
+          2 |       1 | 172.27.0.2  |     5432 | default  | t           | t        | primary  | default     | t              | t
+    (3 rows)

docker/entrypoint.sh

@@ -7,29 +7,36 @@ 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
 
 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://$DOCKER_IP:2379"
         ;;
     zookeeper)
         exec /usr/share/zookeeper/bin/zkServer.sh start-foreground
@@ -56,5 +63,13 @@ export PATRONI_REPLICATION_USERNAME="${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

docs/CONTRIBUTING.rst

@@ -8,7 +8,7 @@ Wanna contribute to Patroni? Yay - here is how!
 Chatting
 --------
 
-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/>`__.
+Just want to chat with other Patroni users?  Looking for interactive troubleshooting help? Join us on channel `#patroni <https://postgresteam.slack.com/archives/C9XPYG92A>`__ in the `PostgreSQL Slack <https://pgtreats.info/slack-invite>`__.
 
 Running tests
 -------------
@@ -19,7 +19,7 @@ Requirements for running behave tests:
 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:
+Install dependencies:
 
 .. code-block:: bash
 
@@ -43,6 +43,126 @@ After you have all dependencies installed, you can run the various test suites:
     # 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 15 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 15 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.
+
 Reporting issues
 ----------------
 

docs/ENVIRONMENT.rst

@@ -33,6 +33,13 @@ It is possible to create new database users right after the successful initializ
 
 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.
 
+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\_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
 ------
 -  **PATRONI\_CONSUL\_HOST**: the host:port for the Consul local agent.
@@ -47,8 +54,10 @@ 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>`__.
 
 Etcd
 ----
@@ -84,6 +93,7 @@ ZooKeeper
 -  **PATRONI\_ZOOKEEPER\_KEY**: (optional) File with the client key.
 -  **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]}``.
 
 .. note::
     It is required to install ``kazoo>=2.6.0`` to support SSL.
@@ -107,9 +117,10 @@ Kubernetes
 -  **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.
@@ -121,11 +132,19 @@ PostgreSQL
 ----------
 -  **PATRONI\_POSTGRESQL\_LISTEN**: IP address + port that Postgres listens to. 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.
 -  **PATRONI\_POSTGRESQL\_CONNECT\_ADDRESS**: IP address + port through which Postgres is accessible from other nodes and applications.
+-  **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 master via streaming replication
+-  **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.
 -  **PATRONI\_REPLICATION\_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\_REPLICATION\_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.
@@ -133,6 +152,7 @@ PostgreSQL
 -  **PATRONI\_REPLICATION\_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.
 -  **PATRONI\_REPLICATION\_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.
 -  **PATRONI\_REPLICATION\_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.
+-  **PATRONI\_REPLICATION\_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\_REPLICATION\_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\_REPLICATION\_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\_SUPERUSER\_USERNAME**: name for the superuser, set during initialization (initdb) and later used by Patroni to connect to the postgres. Also this user is used by pg_rewind.
@@ -143,16 +163,18 @@ PostgreSQL
 -  **PATRONI\_SUPERUSER\_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.
 -  **PATRONI\_SUPERUSER\_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.
 -  **PATRONI\_SUPERUSER\_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.
+-  **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``.
 -  **PATRONI\_REWIND\_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.
 -  **PATRONI\_REWIND\_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.
 -  **PATRONI\_REWIND\_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.
+-  **PATRONI\_REWIND\_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\_REWIND\_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\_REWIND\_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.
 
@@ -172,6 +194,7 @@ 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.
 
 CTL
 ---

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.
 
@@ -35,7 +35,7 @@ To install requirements on a Mac, run the following:
 
 .. _psycopg2_install_options:
 
-**Psycopg2**
+**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.
@@ -62,6 +62,12 @@ There are a few options available:
 
     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:
@@ -73,7 +79,7 @@ Patroni can be installed with pip:
 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 DCS
+    `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
@@ -85,7 +91,7 @@ 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
 
 For example, the command in order to install Patroni together with dependencies for Etcd as a DCS and AWS callbacks is:
 
@@ -103,7 +109,7 @@ 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 master 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
@@ -139,7 +145,7 @@ 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
@@ -171,9 +177,9 @@ 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

@@ -1,390 +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 master 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 master 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 master. 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 master
-    -  **port**: a port of remote master
-    -  **primary\_slot\_name**: which slot on the remote master 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 master, can be different from the list defined in :ref:`postgresql_settings`
-    -  **restore\_command**: command to restore WAL records from the remote master to standby leader, 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.
-
-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``.
-
-.. 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.
-            -  **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 master 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.
-            -  **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.
-            -  **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.
-    -  **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 master can not start streaming from the new master. This option is useful when ``pg_rewind`` can not be used. 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 master 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.
-
-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.

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

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docs/citus.rst

@@ -0,0 +1,355 @@
+.. _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.database`` will be automatically created followed by ``CREATE EXTENSION citus``.
+4. 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!
+5. 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.
+6. 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 ``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, ``patronictl pause`` will
+   enable the maintenance mode by default for the ``group`` that is set in the
+   ``citus`` section, but for example for ``patronictl  switchover`` or
+   ``patronictl remove`` the group must be explicitly specified.
+
+An example of ``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 ``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 ``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

@@ -70,7 +70,7 @@ 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.
@@ -189,9 +189,12 @@ 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)}
 
 # 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
 def setup(app):
-   app.add_stylesheet("custom.css")
+    if hasattr(app, 'add_css_file'):
+        app.add_css_file('custom.css')
+    else:
+        app.add_stylesheet('custom.css')

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 ``patronictl edit-config -s failsafe_mode=true``

docs/dynamic_configuration.rst

@@ -1,89 +1,83 @@
 .. _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 ``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
+-  **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.
+-  **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**:
 
-- 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``).
+   -  **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 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.
+   -  **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.
 
-Some of the PostgreSQL parameters must hold the same values on the master 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:
+      -  **- 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.
 
-- 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
+   -  **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.
 
-For the parameters below, PostgreSQL does not require equal values among the master and all the replicas. However, considering the possibility of a replica to become the master at any time, it doesn't really make sense to set them differently; therefore, Patroni restricts setting their values to the Dynamic configuration
+      -  **- mapname1 systemname1 pguser1**
+      -  **- mapname1 systemname2 pguser2**
 
-- max_wal_senders: 5
-- max_replication_slots: 5
-- wal_keep_segments: 8
-- wal_keep_size: 128MB
+-  **standby\_cluster**: if this section is defined, we want to bootstrap a standby cluster.
 
-These parameters are validated to ensure they are sane, or meet a minimum value.
+   -  **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
 
-There are some other Postgres parameters controlled by Patroni:
+-  **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+.
 
-- 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
+   -  **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.
 
-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>`__
+      -  **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.
 
-When applying the local or dynamic configuration options, the following actions are taken:
+   -  **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).
 
-- 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.
+Note: **slots** is a hashmap while **ignore_slots** is an array. For example:
 
-The parameters would be applied in the following order (run-time are given the highest priority):
+.. code:: YAML
 
-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).
-
-
-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 master is allowed to restore these options from the on-disk dump if these are completely absent from the DCS or if they are invalid.
+        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
+          ...

docs/existing_data.rst

@@ -23,17 +23,19 @@ A Patroni cluster can be started with a data directory from a single-node Postgr
 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.
 
+.. _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 master node
+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 master node.
+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.
 

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 13.
+Currently supported PostgreSQL versions: 9.3 to 15.
+
+**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.
 
@@ -20,17 +22,18 @@ Currently supported PostgreSQL versions: 9.3 to 13.
    :caption: Contents:
 
    README
-   dynamic_configuration
+   patroni_configuration
    rest_api
-   existing_data
-   ENVIRONMENT
-   SETTINGS
-   security
    replica_bootstrap
    replication_modes
-   pause
-   kubernetes
    watchdog
+   pause
+   dcs_failsafe_mode
+   kubernetes
+   citus
+   existing_data
+   security
+   ha_multi_dc
    releases
    CONTRIBUTING
 

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 master:
-
-- 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.
 
@@ -39,7 +36,7 @@ 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 +1,108 @@
+.. _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 ``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 ``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 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
+- **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** :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**
+
+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` 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.
+
+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).
+
+
+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.

docs/pause.rst

@@ -6,7 +6,7 @@ Pause/Resume mode for the cluster
 The goal
 --------
 
-Under certain circumstances Patroni needs to temporary step down from managing the cluster, while still retaining the cluster state in DCS. Possible use cases are uncommon activities on the cluster, such as major version upgrades or corruption recovery. During those activities nodes are often started and stopped for the reason unknown to Patroni, some nodes can be even temporary promoted, violating the assumption of running only one master. Therefore, Patroni needs to be able to "detach" from the running cluster, implementing an equivalent of the maintenance mode in Pacemaker.
+Under certain circumstances Patroni needs to temporarily step down from managing the cluster, while still retaining the cluster state in DCS. Possible use cases are uncommon activities on the cluster, such as major version upgrades or corruption recovery. During those activities nodes are often started and stopped for reasons unknown to Patroni, some nodes can be even temporarily promoted, violating the assumption of running only one primary. Therefore, Patroni needs to be able to "detach" from the running cluster, implementing an equivalent of the maintenance mode in Pacemaker.
 
 
 
@@ -17,16 +17,18 @@ When Patroni runs in a paused mode, it does not change the state of PostgreSQL,
 
 - For each node, the member key in DCS is updated with the current information about the cluster. This causes Patroni to run read-only queries on a member node if the member is running.
 
-- For the Postgres master with the leader lock Patroni updates the lock. If the node with the leader lock stops being the master (i.e. is demoted manually), Patroni will release the lock instead of promoting the node back.
+- 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 master node.
+- 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.
 
-- If 'parallel' masters are detected by Patroni, it emits a warning, but does not demote the masters without the leader lock.
+- If 'parallel' primaries are detected by Patroni, it emits a warning, but does not demote the primary without the leader lock.
 
-- If there is no leader lock in the cluster, the running master acquires the lock. If there is more than one master node, then the first master to acquire the lock wins. If there are no masters altogether, Patroni does not try to promote any replicas. There is an exception in this rule: if there is no leader lock because the old master has demoted itself due to the manual promotion, then only the candidate node mentioned in the promotion request may take the leader lock. When the new leader lock is granted (i.e. after promoting a replica manually), Patroni makes sure the replicas that were streaming from the previous leader will switch to the new one.
+- If there is no leader lock in the cluster, the running primary acquires the lock. If there is more than one primary node, then the first primary to acquire the lock wins. If there are no primary altogether, Patroni does not try to promote any replicas. There is an exception in this rule: if there is no leader lock because the old primary has demoted itself due to the manual promotion, then only the candidate node mentioned in the promotion request may take the leader lock. When the new leader lock is granted (i.e. after promoting a replica manually), Patroni makes sure the replicas that were streaming from the previous leader will switch to the new one.
 
 - When Postgres is stopped, Patroni does not try to start it. When Patroni is stopped, it does not try to stop the Postgres instance it is managing.
 
+- Patroni will not try to remove replication slots that don't represent the other cluster member or are not listed in the configuration of the permanent slots.
+
 User guide
 ----------
 

docs/releases.rst

@@ -3,6 +3,581 @@
 Release notes
 =============
 
+Version 3.0.3
+-------------
+
+**New features**
+
+- Compatibility with PostgreSQL 16 beta1 (Alexander Kukushkin)
+
+  Extended GUC's validator rules.
+
+- Make PostgreSQL GUC's validator extensible (Israel Barth Rubio)
+
+  Validator rules are loaded from YAML files located in ``patroni/postgresql/available_parameters/`` directory. Files are ordered in alphabetical order and applied one after another. It makes possible to have custom validators for non-standard Postgres distributions.
+
+- Added ``restapi.request_queue_size`` option (Andrey Zhidenkov)
+
+  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.
+
+- Call ``initdb`` directly when initializing a new cluster (Matt Baker)
+
+  Previously it was called via ``pg_ctl``, what required a special quoting of parameters passed to ``initdb``.
+
+- Added before stop hook (Le Duane)
+
+  The hook could be configured via ``postgresql.before_stop`` and is executed right before ``pg_ctl stop``. The exit code doesn't impact shutdown process.
+
+- Added support for custom Postgres binary names (Israel Barth Rubio, Polina Bungina)
+
+  When using a custom Postgres distribution it may be the case that the Postgres binaries are compiled with different names other than the ones used by the community Postgres distribution. Custom binary names could be configured using ``postgresql.bin_name.*`` and ``PATRONI_POSTGRESQL_BIN_*`` environment variables.
+
+
+**Improvements**
+
+- Various improvements of ``patroni --validate-config`` (Polina Bungina)
+
+  -  Make ``bootstrap.initdb`` optional. It is only required for new clusters, but ``patroni --validate-config`` was complaining if it was missing in the config.
+  -  Don't error out when ``postgresql.bin_dir`` is empty or not set. Try to first find Postgres binaries in the default PATH instead.
+  -  Make ``postgresql.authentication.rewind`` section optional. If it is missing, Patroni is using the superuser.
+
+- Improved error reporting in ``patronictl`` (Israel Barth Rubio)
+
+  The ``\n`` symbol was rendered as it is, instead of the actual newline symbol.
+
+
+**Bugfixes**
+
+- Fixed issue in Citus support (Alexander Kukushkin)
+
+  If the REST API call from the promoted worker to the coordinator failed during switchover it was leaving the given Citus group blocked during indefinite time.
+
+- Allow `etcd3` URL in `--dcs-url` option of `patronictl` (Israel Barth Rubio)
+
+  If users attempted to pass a `etcd3` URL through `--dcs-url` option of `patronictl` they would face an exception.
+
+
+Version 3.0.2
+-------------
+
+.. warning::
+    Version 3.0.2 dropped support of Python older than 3.6.
+
+
+**New features**
+
+- Added sync standby replica status to ``/metrics`` endpoint (Thomas von Dein, Alexander Kukushkin)
+
+  Before were only reporting ``primary``/``standby_leader``/``replica``.
+
+- User-friendly handling of ``PAGER`` in ``patronictl`` (Israel Barth Rubio)
+
+  It makes pager configurable via ``PAGER`` environment variable, which overrides default ``less`` and ``more``.
+
+- Make K8s retriable HTTP status code configurable (Alexander)
+
+  On some managed platforms it is possible to get status code ``401 Unauthorized``, which sometimes gets resolved after a few retries.
+
+
+**Improvements**
+
+- Set ``hot_standby`` to ``off`` during custom bootstrap only if ``recovery_target_action`` is set to ``promote`` (Alexander)
+
+  It was necessary to make ``recovery_target_action=pause`` work correctly.
+
+- Don't allow ``on_reload`` callback to kill other callbacks (Alexander)
+
+  ``on_start``/``on_stop``/``on_role_change`` are usually used to add/remove Virtual IP and ``on_reload`` should not interfere with them.
+
+- Switched to ``IMDSFetcher`` in aws callback example script (Polina Bungina)
+
+  The ``IMDSv2`` requires a token to work with and the ``IMDSFetcher`` handles it transparently.
+
+
+**Bugfixes**
+
+- Fixed ``patronictl switchover`` on Citus cluster running on Kubernetes (Lukáš Lalinský)
+
+  It didn't work for namespaces different from ``default``.
+
+- Don't write to ``PGDATA`` if major version is not known (Alexander)
+
+  If right after the start ``PGDATA`` was empty (maybe wasn't yet mounted), Patroni was making a false assumption about PostgreSQL version and falsely creating ``recovery.conf`` file even if the actual major version is v10+.
+
+- Fixed bug with Citus metadata after coordinator failover (Alexander)
+
+  The ``citus_set_coordinator_host()`` call doesn't cause metadata sync and the change was invisible on worker nodes. The issue is solved by switching to ``citus_update_node()``.
+
+- Use etcd hosts listed in the config file as a fallback when all etcd nodes "failed" (Alexander)
+
+  The etcd cluster may change topology over time and Patroni tries to follow it. If at some point all nodes became unreachable Patroni will use a combination of nodes from the config plus the last known topology when trying to reconnect.
+
+
+Version 3.0.1
+-------------
+
+**Bugfixes**
+
+- Pass proper role name to an ``on_role_change`` callback script'. (Alexander Kukushkin, Polina Bungina)
+
+  Patroni used to erroneously pass ``promoted`` role to an ``on_role_change`` callback script on promotion. The passed role name changed back to ``master``. This regression was introduced in 3.0.0.
+
+
+Version 3.0.0
+-------------
+
+This version adds integration with `Citus <https://www.citusdata.com>`__ and makes it possible to survive temporary DCS outages without demoting primary.
+
+.. warning::
+   - Version 3.0.0 is the last release supporting Python 2.7. Upcoming release will drop support of Python versions older than 3.7.
+
+   - The RAFT support is deprecated. We will do our best to maintain it, but take neither guarantee nor responsibility for possible issues.
+
+   - This version is the first step in getting rid of the "master", in favor of "primary". Upgrading to the next major release will work reliably only if you run at least 3.0.0.
+
+
+**New features**
+
+- DCS failsafe mode (Alexander Kukushkin, Polina Bungina)
+
+  If the feature is enabled it will allow Patroni cluster to survive temporary DCS outages. You can find more details in the :ref:`documentation <dcs_failsafe_mode>`.
+
+- Citus support (Alexander, Polina, Jelte Fennema)
+
+  Patroni enables easy deployment and management of `Citus <https://www.citusdata.com>`__ clusters with HA. Please check :ref:`here <citus>` page for more information.
+
+
+**Improvements**
+
+- Suppress recurring errors when dropping unknown but active replication slots (Michael Banck)
+
+  Patroni will still write these logs, but only in DEBUG.
+
+- Run only one monitoring query per HA loop (Alexander)
+
+  It wasn't the case if synchronous replication is enabled.
+
+- Keep only latest failed data directory (William Albertus Dembo)
+
+  If bootstrap failed Patroni used to rename $PGDATA folder with timestamp suffix. From now on the suffix will be ``.failed`` and if such folder exists it is removed before renaming.
+
+- Improved check of synchronous replication connections (Alexander)
+
+  When the new host is added to the ``synchronous_standby_names`` it will be set as synchronous in DCS only when it managed to catch up with the primary in addition to ``pg_stat_replication.sync_state = 'sync'``.
+
+
+**Removed functionality**
+
+- Remove ``patronictl scaffold`` (Alexander)
+
+  The only reason for having it was a hacky way of running standby clusters.
+
+
+Version 2.1.7
+-------------
+
+**Bugfixes**
+
+- Fixed little incompatibilities with legacy python modules (Alexander Kukushkin)
+
+  They prevented from building/running Patroni on Debian buster/Ubuntu bionic.
+
+
+Version 2.1.6
+-------------
+
+**Improvements**
+
+- Fix annoying exceptions on ssl socket shutdown (Alexander Kukushkin)
+
+  The HAProxy is closing connections as soon as it got the HTTP Status code leaving no time for Patroni to properly shutdown SSL connection.
+
+- Adjust example Dockerfile for arm64 (Polina Bungina)
+
+  Remove explicit ``amd64`` and ``x86_64``, don't remove ``libnss_files.so.*``.
+
+
+**Security improvements**
+
+- Enforce ``search_path=pg_catalog`` for non-replication connections (Alexander)
+
+  Since Patroni is heavily relying on superuser connections, we want to protect it from the possible attacks carried out using user-defined functions and/or operators in ``public`` schema with the same name and signature as the corresponding objects in ``pg_catalog``. For that, ``search_path=pg_catalog`` is enforced for all connections created by Patroni (except replication connections).
+
+- Prevent passwords from being recorded in ``pg_stat_statements`` (Feike Steenbergen)
+
+  It is achieved by setting ``pg_stat_statements.track_utility=off`` when creating users.
+
+
+**Bugfixes**
+
+- Declare ``proxy_address`` as optional (Denis Laxalde)
+
+  As it is effectively a non-required option.
+
+- Improve behaviour of the insecure option (Alexander)
+
+  Ctl's ``insecure`` option didn't work properly when client certificates were used for REST API requests.
+
+- Take watchdog configuration from ``bootstrap.dcs`` when the new cluster is bootstrapped (Matt Baker)
+
+  Patroni used to initially configure watchdog with defaults when bootstrapping a new cluster rather than taking configuration used to bootstrap the DCS.
+
+- Fix the way file extensions are treated while finding executables in WIN32 (Martín Marqués)
+
+  Only add ``.exe`` to a file name if it has no extension yet.
+
+- Fix Consul TTL setup (Alexander)
+
+  We used ``ttl/2.0`` when setting the value on the HTTPClient, but forgot to multiply the current value by 2 in the class' property. It was resulting in Consul TTL off by twice.
+
+
+**Removed functionality**
+
+- Remove ``patronictl configure`` (Polina)
+
+  There is no more need for a separate ``patronictl`` config creation.
+
+
+Version 2.1.5
+-------------
+
+This version enhances compatibility with PostgreSQL 15 and declares Etcd v3 support as production ready. The Patroni on Raft remains in Beta.
+
+**New features**
+
+- Improve ``patroni --validate-config`` (Denis Laxalde)
+
+  Exit with code 1 if config is invalid and print errors to stderr.
+
+- Don't drop replication slots in pause (Alexander Kukushkin)
+
+  Patroni is automatically creating/removing physical replication slots when members are joining/leaving the cluster. In pause slots will no longer be removed.
+
+- Support the ``HEAD`` request method for monitoring endpoints (Robert Cutajar)
+
+  If used instead of ``GET`` Patroni will return only the HTTP Status Code.
+
+- Support behave tests on Windows (Alexander)
+
+  Emulate graceful Patroni shutdown (``SIGTERM``) on Windows by introduce the new REST API endpoint ``POST /sigterm``.
+
+- Introduce ``postgresql.proxy_address`` (Alexander)
+
+  It will be written to the member key in DCS as the ``proxy_url`` and could be used/useful for service discovery.
+
+
+**Stability improvements**
+
+- Call ``pg_replication_slot_advance()`` from a thread (Alexander)
+
+  On busy clusters with many logical replication slots the ``pg_replication_slot_advance()`` call was affecting the main HA loop and could result in the member key expiration.
+
+- Archive possibly missing WALs before calling ``pg_rewind`` on the old primary (Polina Bungina)
+
+  If the primary crashed and was down during considerable time, some WAL files could be missing from archive and from the new primary. There is a chance that ``pg_rewind`` could remove these WAL files from the old primary making it impossible to start it as a standby. By archiving ``ready`` WAL files we not only mitigate this problem but in general improving continues archiving experience.
+
+- Ignore ``403`` errors when trying to create Kubernetes Service (Nick Hudson, Polina)
+
+  Patroni was spamming logs by unsuccessful attempts to create the service, which in fact could already exist.
+
+- Improve liveness probe (Alexander)
+
+  The liveness problem will start failing if the heartbeat loop is running longer than `ttl` on the primary or `2*ttl` on the replica. That will allow us to use it as an alternative for :ref:`watchdog <watchdog>` on Kubernetes.
+
+- Make sure only sync node tries to grab the lock when switchover (Alexander, Polina)
+
+  Previously there was a slim chance that up-to-date async member could become the leader if the manual switchover was performed without specifying the target.
+
+- Avoid cloning while bootstrap is running (Ants Aasma)
+
+  Do not allow a create replica method that does not require a leader to be triggered while the cluster bootstrap is running.
+
+- Compatibility with kazoo-2.9.0 (Alexander)
+
+  Depending on python version the ``SequentialThreadingHandler.select()`` method may raise ``TypeError`` and ``IOError`` exceptions if ``select()`` is called on the closed socket.
+
+- Explicitly shut down SSL connection before socket shutdown (Alexander)
+
+  Not doing it resulted in ``unexpected eof while reading`` errors with OpenSSL 3.0.
+
+- Compatibility with `prettytable>=2.2.0` (Alexander)
+
+  Due to the internal API changes the cluster name header was shown on the incorrect line.
+
+
+**Bugfixes**
+
+- Handle expired token for Etcd lease_grant (monsterxx03)
+
+  In case of error get the new token and retry request.
+
+- Fix bug in the ``GET /read-only-sync`` endpoint (Alexander)
+
+  It was introduced in previous release and effectively never worked.
+
+- Handle the case when data dir storage disappeared (Alexander)
+
+  Patroni is periodically checking that the PGDATA is there and not empty, but in case of issues with storage the ``os.listdir()`` is raising the ``OSError`` exception, breaking the heart-beat loop.
+
+- Apply ``master_stop_timeout`` when waiting for user backends to close (Alexander)
+
+  Something that looks like user backend could be in fact a background worker (e.g., Citus Maintenance Daemon) that is failing to stop.
+
+- Accept ``*:<port>`` for ``postgresql.listen`` (Denis)
+
+  The ``patroni --validate-config`` was complaining about it being invalid.
+
+- Timeouts fixes in Raft (Alexander)
+
+  When Patroni or patronictl are starting they try to get Raft cluster topology from known members. These calls were made without proper timeouts.
+
+- Forcefully update consul service if token was changed (John A. Lotoski)
+
+  Not doing so results in errors "rpc error making call: rpc error making call: ACL not found".
+
+
+Version 2.1.4
+-------------
+
+**New features**
+
+- Improve ``pg_rewind`` behavior on typical Debian/Ubuntu systems (Gunnar "Nick" Bluth)
+
+  On Postgres setups that keep `postgresql.conf` outside of the data directory (e.g. Ubuntu/Debian packages), ``pg_rewind --restore-target-wal``  fails to figure out the value of the ``restore_command``.
+
+- Allow setting ``TLSServerName`` on Consul service checks (Michael Gmelin)
+
+  Useful when checks are performed by IP and the Consul ``node_name`` is not a FQDN.
+
+- Added ``ppc64le`` support in watchdog (Jean-Michel Scheiwiler)
+
+  And fixed watchdog support on some non-x86 platforms.
+
+- Switched aws.py callback from ``boto`` to ``boto3`` (Alexander Kukushkin)
+
+ ``boto``  2.x is abandoned since 2018 and fails with python 3.9.
+
+- Periodically refresh service account token on K8s (Haitao Li)
+
+  Since Kubernetes v1.21 service account tokens expire in 1 hour.
+
+- Added ``/read-only-sync`` monitoring endpoint (Dennis4b)
+
+  It is similar to the ``/read-only`` but includes only synchronous replicas.
+
+
+**Stability improvements**
+
+- Don't copy the logical replication slot to a replica if there is a configuration mismatch in the logical decoding setup with the primary (Alexander)
+
+  A replica won't copy a logical replication slot from the primary anymore if the slot doesn't match the ``plugin`` or ``database`` configuration options. Previously, the check for whether the slot matches those configuration options was not performed until after the replica copied the slot and started with it, resulting in unnecessary and repeated restarts.
+
+- Special handling of recovery configuration parameters for PostgreSQL v12+ (Alexander)
+
+  While starting as replica Patroni should be able to update ``postgresql.conf`` and restart/reload if the leader address has changed by caching current parameters values instead of querying them from ``pg_settings``.
+
+- Better handling of IPv6 addresses in the ``postgresql.listen`` parameters (Alexander)
+
+  Since the ``listen`` parameter has a port, people try to put IPv6 addresses into square brackets, which were not correctly stripped when there is more than one IP in the list.
+
+- Use ``replication`` credentials when performing divergence check only on PostgreSQL v10 and older (Alexander)
+
+  If ``rewind`` is enabled, Patroni will again use either ``superuser`` or ``rewind`` credentials on newer Postgres versions.
+
+
+**Bugfixes**
+
+- Fixed missing import of ``dateutil.parser`` (Wesley Mendes)
+
+  Tests weren't failing only because it was also imported from other modules.
+
+- Ensure that ``optime`` annotation is a string (Sebastian Hasler)
+
+  In certain cases Patroni was trying to pass it as numeric.
+
+- Better handling of failed ``pg_rewind`` attempt (Alexander)
+
+  If the primary becomes unavailable during ``pg_rewind``, ``$PGDATA`` will be left in a broken state. Following that,  Patroni will remove the data directory even if this is not allowed by the configuration.
+
+- Don't remove ``slots`` annotations from the leader ``ConfigMap``/``Endpoint`` when PostgreSQL isn't ready (Alexander)
+
+  If ``slots`` value isn't passed the annotation will keep the current value.
+
+- Handle concurrency problem with K8s API watchers (Alexander)
+
+  Under certain (unknown) conditions watchers might become stale; as a result, ``attempt_to_acquire_leader()`` method could fail due to the HTTP status code 409. In that case we reset watchers connections and restart from scratch.
+
+
+Version 2.1.3
+-------------
+
+**New features**
+
+- Added support for encrypted TLS keys for ``patronictl`` (Alexander Kukushkin)
+
+  It could be configured via ``ctl.keyfile_password`` or the ``PATRONI_CTL_KEYFILE_PASSWORD`` environment variable.
+
+- Added more metrics to the /metrics endpoint (Alexandre Pereira)
+
+  Specifically, ``patroni_pending_restart`` and ``patroni_is_paused``.
+
+- Make it possible to specify multiple hosts in the standby cluster configuration (Michael Banck)
+
+  If the standby cluster is replicating from the Patroni cluster it might be nice to rely on client-side failover which is available in ``libpq`` since PostgreSQL v10. That is, the ``primary_conninfo`` on the standby leader and ``pg_rewind`` setting ``target_session_attrs=read-write`` in the connection string. The ``pgpass`` file will be generated with multiple lines (one line per host), and instead of calling ``CHECKPOINT`` on the primary cluster nodes the standby cluster will wait for ``pg_control`` to be updated.
+
+**Stability improvements**
+
+- Compatibility with legacy ``psycopg2`` (Alexander)
+
+  For example, the ``psycopg2`` installed from Ubuntu 18.04 packages doesn't have the ``UndefinedFile`` exception yet.
+
+- Restart ``etcd3`` watcher if all Etcd nodes don't respond (Alexander)
+
+  If the watcher is alive the ``get_cluster()`` method continues returning stale information even if all Etcd nodes are failing.
+
+- Don't remove the leader lock in the standby cluster while paused (Alexander)
+
+  Previously the lock was maintained only by the node that was running as a primary and not a standby leader.
+
+**Bugfixes**
+
+- Fixed bug in the standby-leader bootstrap (Alexander)
+
+  Patroni was considering bootstrap as failed if Postgres didn't start accepting connections after 60 seconds. The bug was introduced in the 2.1.2 release.
+
+- Fixed bug with failover to a cascading standby (Alexander)
+
+  When figuring out which slots should be created on cascading standby we forgot to take into account that the leader might be absent.
+
+- Fixed small issues in Postgres config validator (Alexander)
+
+  Integer parameters introduced in PostgreSQL v14 were failing to validate because min and max values were quoted in the validator.py
+
+- Use replication credentials when checking leader status (Alexander)
+
+  It could be that the ``remove_data_directory_on_diverged_timelines`` is set, but there is no ``rewind_credentials`` defined and superuser access between nodes is not allowed.
+
+- Fixed "port in use" error on REST API certificate replacement (Ants Aasma)
+
+  When switching certificates there was a race condition with a concurrent API request. If there is one active during the replacement period then the replacement will error out with a port in use error and Patroni gets stuck in a state without an active API server.
+
+- Fixed a bug in cluster bootstrap if passwords contain ``%`` characters (Bastien Wirtz)
+
+  The bootstrap method executes the ``DO`` block, with all parameters properly quoted, but the ``cursor.execute()`` method didn't like an empty list with parameters passed.
+
+- Fixed the "AttributeError: no attribute 'leader'" exception (Hrvoje Milković)
+
+  It could happen if the synchronous mode is enabled and the DCS content was wiped out.
+
+- Fix bug in divergence timeline check (Alexander)
+
+  Patroni was falsely assuming that timelines have diverged. For pg_rewind it didn't create any problem, but if pg_rewind is not allowed and the ``remove_data_directory_on_diverged_timelines`` is set, it resulted in reinitializing the former leader.
+
+
+Version 2.1.2
+-------------
+
+**New features**
+
+- Compatibility with ``psycopg>=3.0`` (Alexander Kukushkin)
+
+  By default ``psycopg2`` is preferred. `psycopg>=3.0` will be used only if ``psycopg2`` is not available or its version is too old.
+
+- Add ``dcs_last_seen`` field to the REST API (Michael Banck)
+
+  This field notes the last time (as unix epoch) a cluster member has successfully communicated with the DCS. This is useful to identify and/or analyze network partitions.
+
+- Release the leader lock when ``pg_controldata`` reports "shut down" (Alexander)
+
+  To solve the problem of slow switchover/shutdown in case ``archive_command`` is slow/failing, Patroni will remove the leader key immediately after ``pg_controldata`` started reporting PGDATA as ``shut down`` cleanly and it verified that there is at least one replica that received all changes. If there are no replicas that fulfill this condition the leader key is not removed and the old behavior is retained, i.e. Patroni will keep updating the lock.
+
+- Add ``sslcrldir`` connection parameter support (Kostiantyn Nemchenko)
+
+  The new connection parameter was introduced in the PostgreSQL v14.
+
+- Allow setting ACLs for ZNodes in Zookeeper (Alwyn Davis)
+
+  Introduce a new configuration option ``zookeeper.set_acls`` so that Kazoo will apply a default ACL for each ZNode that it creates.
+
+
+**Stability improvements**
+
+- Delay the next attempt of recovery till next HA loop (Alexander)
+
+  If Postgres crashed due to out of disk space (for example) and fails to start because of that Patroni is too eagerly trying to recover it flooding logs.
+
+- Add log before demoting, which can take some time (Michael)
+
+  It can take some time for the demote to finish and it might not be obvious from looking at the logs what exactly is going on.
+
+- Improve "I am" status messages (Michael)
+
+  ``no action. I am a secondary ({0})`` vs ``no action. I am ({0}), a secondary``
+
+- Cast to int ``wal_keep_segments`` when converting to ``wal_keep_size`` (Jorge Solórzano)
+
+  It is possible to specify ``wal_keep_segments`` as a string in the global :ref:`dynamic configuration <dynamic_configuration>` and due to Python being a dynamically typed language the string was simply multiplied. Example: ``wal_keep_segments: "100"`` was converted to ``100100100100100100100100100100100100100100100100MB``.
+
+- Allow switchover only to sync nodes when synchronous replication is enabled (Alexander)
+
+  In addition to that do the leader race only against known synchronous nodes.
+
+- Use cached role as a fallback when Postgres is slow (Alexander)
+
+  In some extreme cases Postgres could be so slow that the normal monitoring query does not finish in a few seconds. The ``statement_timeout`` exception not being properly handled could lead to the situation where Postgres was not demoted on time when the leader key expired or the update failed. In case of such exception Patroni will use the cached ``role`` to determine whether Postgres is running as a primary.
+
+- Avoid unnecessary updates of the member ZNode (Alexander)
+
+  If no values have changed in the members data, the update should not happen.
+
+- Optimize checkpoint after promote (Alexander)
+
+  Avoid doing ``CHECKPOINT`` if the latest timeline is already stored in ``pg_control``. It helps to avoid unnecessary ``CHECKPOINT`` right after initializing the new cluster with ``initdb``.
+
+- Prefer members without ``nofailover`` when picking sync nodes (Alexander)
+
+  Previously sync nodes were selected only based on the replication lag, hence the node with ``nofailover`` tag had the same chances to become synchronous as any other node. That behavior was confusing and dangerous at the same time because in case of a failed primary the failover could not happen automatically.
+
+- Remove duplicate hosts from the etcd machine cache (Michael)
+
+  Advertised client URLs in the etcd cluster could be misconfigured. Removing duplicates in Patroni in this case is a low-hanging fruit.
+
+
+**Bugfixes**
+
+- Skip temporary replication slots while doing slot management (Alexander)
+
+  Starting from v10 ``pg_basebackup`` creates a temporary replication slot for WAL streaming and Patroni was trying to drop it because the slot name looks unknown. In order to fix it, we skip all temporary slots when querying ``pg_stat_replication_slots`` view.
+
+- Ensure ``pg_replication_slot_advance()`` doesn't timeout (Alexander)
+
+  Patroni was using the default ``statement_timeout`` in this case and once the call failed there are very high chances that it will never recover, resulting in increased size of ``pg_wal`` and ``pg_catalog`` bloat.
+
+- The ``/status`` wasn't updated on demote (Alexander)
+
+  After demoting PostgreSQL the old leader updates the last LSN in DCS. Starting from ``2.1.0`` the new ``/status`` key was introduced, but the optime was still written to the ``/optime/leader``.
+
+- Handle DCS exceptions when demoting (Alexander)
+
+  While demoting the master due to failure to update the leader lock it could happen that DCS goes completely down and the ``get_cluster()`` call raises an exception. Not being handled properly it results in Postgres remaining stopped until DCS recovers.
+
+- The ``use_unix_socket_repl`` didn't work is some cases (Alexander)
+
+  Specifically, if ``postgresql.unix_socket_directories`` is not set. In this case Patroni is supposed to use the default value from ``libpq``.
+
+- Fix a few issues with Patroni REST API (Alexander)
+
+  The ``clusters_unlocked`` sometimes could be not defined, what resulted in exceptions in the ``GET /metrics`` endpoint. In addition to that the error handling method was assuming that the ``connect_address`` tuple always has two elements, while in fact there could be more in case of IPv6.
+
+- Wait for newly promoted node to finish recovery before deciding to rewind (Alexander)
+
+  It could take some time before the actual promote happens and the new timeline is created. Without waiting replicas could come to the conclusion that rewind isn't required.
+
+- Handle missing timelines in a history file when deciding to rewind (Alexander)
+
+  If the current replica timeline is missing in the history file on the primary the replica was falsely assuming that rewind isn't required.
+
+
 Version 2.1.1
 -------------
 
@@ -866,7 +1441,7 @@ Version 1.6.1
 
 - Kill all children along with the callback process before starting the new one (Alexander Kukushkin)
 
-  Not doing so makes it hard to implement callbacks in bash and eventually can lead to the situation when two callbacks are running at the same time. 
+  Not doing so makes it hard to implement callbacks in bash and eventually can lead to the situation when two callbacks are running at the same time.
 
 - Fix 'start failed' issue (Alexander Kukushkin)
 
@@ -1164,7 +1739,7 @@ This version implements support of permanent replication slots, adds support of
 
 - Permanent replication slots (Alexander Kukushkin)
 
-  Permanent replication slots are preserved on failover/switchover, that is, Patroni on the new primary will create configured replication slots right after doing promote. Slots could be configured with the help of `patronictl edit-config`. The initial configuration could be also done in the :ref:`bootstrap.dcs <settings>`.
+  Permanent replication slots are preserved on failover/switchover, that is, Patroni on the new primary will create configured replication slots right after doing promote. Slots could be configured with the help of `patronictl edit-config`. The initial configuration could be also done in the :ref:`bootstrap.dcs <yaml_configuration>`.
 
 - Add pgbackrest support (Yogesh Sharma)
 
@@ -2009,7 +2584,7 @@ When upgrading from v0.90 or below, always upgrade all replicas before the maste
 
   Patroni SIGHUP or POST to /reload will make it re-read the configuration file.
 
-  See the :ref:`dynamic configuration <dynamic_configuration>`  for the details on which parameters can be changed and the order of processing difference configuration sources.
+  See the :ref:`Patroni configuration <patroni_configuration>` for the details on which parameters can be changed and the order of processing difference configuration sources.
 
   The configuration file format *has changed* since the v0.90. Patroni is still compatible with the old configuration files, but in order to take advantage of the bootstrap parameters one needs to change it. Users are encourage to update them by referring to the :ref:`dynamic configuration documentation page <dynamic_configuration>`.
 

docs/replica_bootstrap.rst

@@ -63,7 +63,7 @@ Building replicas
 -----------------
 
 Patroni uses tried and proven ``pg_basebackup`` in order to create new replicas. One downside of it is that it requires
-a running master node. Another one is the lack of 'on-the-fly' compression for the backup data and no built-in cleanup
+a running leader node. Another one is the lack of 'on-the-fly' compression for the backup data and no built-in cleanup
 for outdated backup files. Some people prefer other backup solutions, such as ``WAL-E``, ``pgBackRest``, ``Barman`` and
 others, or simply roll their own scripts. In order to accommodate all those use-cases Patroni supports running custom
 scripts to clone a new replica. Those are configured in the ``postgresql`` configuration block:
@@ -77,7 +77,7 @@ 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 +89,7 @@ example: wal_e
             - basebackup
         wal_e:
             command: patroni_wale_restore
-            no_master: 1
+            no_leader: 1
             envdir: {{WALE_ENV_DIR}}
             use_iam: 1
         basebackup:
@@ -123,11 +123,11 @@ to execute and any custom parameters that should be passed to that command. All
 --role
     Always 'replica'
 --connstring
-    Connection string to connect to the cluster member to clone from (master or other replica). The user in the
+    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
-running master or replicas. In that case, an empty string will be passed in a connection string. This is useful for
+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.
 
 A special ``keep_data`` parameter, if defined, will instruct Patroni to  not clean PGDATA folder before calling restore.
@@ -137,7 +137,7 @@ A special ``no_params`` parameter, if defined, restricts passing parameters to c
 A ``basebackup`` method is a special case: it will be used if
 ``create_replica_methods`` is empty, although it is possible
 to list it explicitly among the ``create_replica_methods`` methods. This method initializes a new replica with the
-``pg_basebackup``, the base backup is taken from the master unless there are replicas with ``clonefrom`` tag, in which case one
+``pg_basebackup``, the base backup is taken from the leader unless there are replicas with ``clonefrom`` tag, in which case one
 of such replicas will be used as the origin for pg_basebackup. It works without any configuration; however, it is
 possible to specify a ``basebackup`` configuration section. Same rules as with the other method configuration apply,
 namely, only long (with --) options should be specified there. Not all parameters make sense, if you override a connection
@@ -176,10 +176,10 @@ Standby cluster
 ---------------
 
 Another available option is to run a "standby cluster", that contains only of
-standby nodes replicating from some remote master. This type of clusters has:
+standby nodes replicating from some remote node. This type of clusters has:
 
 * "standby leader", that behaves pretty much like a regular cluster leader,
-  except it replicates from a remote master.
+  except it replicates from a remote node.
 
 * cascade replicas, that are replicating from standby leader.
 
@@ -187,6 +187,13 @@ Standby leader holds and updates a leader lock in DCS. If the leader lock
 expires, cascade replicas will perform an election to choose another leader
 from the standbys.
 
+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
+primary cluster.
+
 For the sake of flexibility, you can specify methods of creating a replica and
 recovery WAL records when a cluster is in the "standby mode" by providing
 `create_replica_methods` key in `standby_cluster` section. It is distinct from
@@ -212,4 +219,9 @@ in a patroni configuration:
 Note, that these options will be applied only once during cluster bootstrap,
 and the only way to change them afterwards is through DCS.
 
+Patroni expects to find `postgresql.conf` or `postgresql.conf.backup` in PGDATA
+of the remote primary and will not start if it does not find it after a
+basebackup. If the remote primary keeps its `postgresql.conf` elsewhere, it is
+your responsibility to copy it to PGDATA.
+
 If you use replication slots on the standby cluster, you must also create the corresponding replication slot on the primary cluster.  It will not be done automatically by the standby cluster implementation.  You can use Patroni's permanent replication slots feature on the primary cluster to maintain a replication slot with the same name as ``primary_slot_name``, or its default value if ``primary_slot_name`` is not provided.

docs/replication_modes.rst

@@ -13,7 +13,7 @@ In asynchronous mode the cluster is allowed to lose some committed transactions
 
 The amount of transactions that can be lost is controlled via ``maximum_lag_on_failover`` parameter. Because the primary transaction log position is not sampled in real time, in reality the amount of lost data on failover is worst case bounded by  ``maximum_lag_on_failover`` bytes of transaction log plus the amount that is written in the last ``ttl`` seconds (``loop_wait``/2 seconds in the average case). However typical steady state replication delay is well under a second.
 
-By default, when running leader elections, Patroni does not take into account the current timeline of replicas, what in some cases could be undesirable behavior. You can prevent the node not having the same timeline as a former master become the new leader by changing the value of ``check_timeline`` parameter to ``true``.
+By default, when running leader elections, Patroni does not take into account the current timeline of replicas, what in some cases could be undesirable behavior. You can prevent the node not having the same timeline as a former primary become the new leader by changing the value of ``check_timeline`` parameter to ``true``.
 
 PostgreSQL synchronous replication
 ----------------------------------
@@ -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

@@ -7,12 +7,11 @@ Patroni has a rich REST API, which is used by Patroni itself during the leader r
 
 Health check endpoints
 ----------------------
-For all health check ``GET`` requests Patroni returns a JSON document with the status of the node, along with the HTTP status code. If you don't want or don't need the JSON document, you might consider using the ``OPTIONS`` method instead of ``GET``.
+For all health check ``GET`` requests Patroni returns a JSON document with the status of the node, along with the HTTP status code. If you don't want or don't need the JSON document, you might consider using the ``HEAD`` or ``OPTIONS`` method instead of ``GET``.
 
 - 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``
@@ -44,8 +43,11 @@ For all health check ``GET`` requests Patroni returns a JSON document with the s
 
 - ``GET /synchronous`` or ``GET /sync``: returns HTTP status code **200** only when the Patroni node is running as a synchronous standby.
 
+- ``GET /read-only-sync``: like the above endpoint, but also includes the primary.
+
 - ``GET /asynchronous`` or ``GET /async``: returns HTTP status code **200** only when the Patroni node is running as an asynchronous standby.
 
+
 - ``GET /asynchronous?lag=<max-lag>`` or ``GET /async?lag=<max-lag>``: asynchronous standby check endpoint. In addition to checks from ``asynchronous`` or ``async``, it also checks replication latency and returns status code **200** only when it is below specified value. The key cluster.last_leader_operation from DCS is used for Leader wal position and compute latency on replica for performance reasons. max-lag can be specified in bytes (integer) or in human readable values, for e.g. 16kB, 64MB, 1GB.
 
   - ``GET /async?lag=1048576``
@@ -55,7 +57,7 @@ For all health check ``GET`` requests Patroni returns a JSON document with the s
 
 - ``GET /health``: returns HTTP status code **200** only when PostgreSQL is up and running.
 
-- ``GET /liveness``: always returns HTTP status code **200** what only indicates that Patroni is running. Could be used for ``livenessProbe``.
+- ``GET /liveness``: returns HTTP status code **200** if Patroni heartbeat loop is properly running and **503** if the last run was more than ``ttl`` seconds ago on the primary or ``2*ttl`` on the replica. Could be used for ``livenessProbe``.
 
 - ``GET /readiness``: returns HTTP status code **200** when the Patroni node is running as the leader or when PostgreSQL is up and running. The endpoint could be used for ``readinessProbe`` when it is not possible to use Kubernetes endpoints for leader elections (OpenShift).
 
@@ -110,6 +112,69 @@ The ``GET /patroni`` is used by Patroni during the leader race. It also could be
       }
     }
 
+
+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"} 020103
+	# HELP patroni_postgres_running Value is 1 if Postgres is running, 0 otherwise.
+	# TYPE patroni_postgres_running gauge
+	patroni_postgres_running{scope="batman"} 1
+	# HELP patroni_postmaster_start_time Epoch seconds since Postgres started.
+	# TYPE patroni_postmaster_start_time gauge
+	patroni_postmaster_start_time{scope="batman"} 1657656955.179243
+	# HELP patroni_master Value is 1 if this node is the leader, 0 otherwise.
+	# TYPE patroni_master gauge
+	patroni_master{scope="batman"} 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"} 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"} 0
+	# HELP patroni_replica Value is 1 if this node is a replica, 0 otherwise.
+	# TYPE patroni_replica gauge
+	patroni_replica{scope="batman"} 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"} 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"} 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"} 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"} 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"} 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"} 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"} 0
+	# HELP patroni_postgres_timeline Postgres timeline of this node (if running), 0 otherwise.
+	# TYPE patroni_postgres_timeline counter
+	patroni_postgres_timeline{scope="batman"} 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"} 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"} 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"} 1
+
+
 Cluster status endpoints
 ------------------------
 
@@ -365,7 +430,7 @@ 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

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 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 ``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 ``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/watchdog.rst

@@ -3,7 +3,7 @@
 Watchdog support
 ================
 
-Having multiple PostgreSQL servers running as master can result in transactions lost due to diverging timelines. This situation is also called a split-brain problem. To avoid split-brain Patroni needs to ensure PostgreSQL will not accept any transaction commits after leader key expires in the DCS. Under normal circumstances Patroni will try to achieve this by stopping PostgreSQL when leader lock update fails for any reason. However, this may fail to happen due to various reasons:
+Having multiple PostgreSQL servers running as primary can result in transactions lost due to diverging timelines. This situation is also called a split-brain problem. To avoid split-brain Patroni needs to ensure PostgreSQL will not accept any transaction commits after leader key expires in the DCS. Under normal circumstances Patroni will try to achieve this by stopping PostgreSQL when leader lock update fails for any reason. However, this may fail to happen due to various reasons:
 
 - Patroni has crashed due to a bug, out-of-memory condition or by being accidentally killed by a system administrator.
 
@@ -13,7 +13,7 @@ Having multiple PostgreSQL servers running as master can result in transactions
 
 To guarantee correct behavior under these conditions Patroni supports watchdog devices. Watchdog devices are software or hardware mechanisms that will reset the whole system when they do not get a keepalive heartbeat within a specified timeframe. This adds an additional layer of fail safe in case usual Patroni split-brain protection mechanisms fail.
 
-Patroni will try to activate the watchdog before promoting PostgreSQL to master. If watchdog activation fails and watchdog mode is ``required`` then the node will refuse to become master. When deciding to participate in leader election Patroni will also check that watchdog configuration will allow it to become leader at all. After demoting PostgreSQL (for example due to a manual failover) Patroni will disable the watchdog again. Watchdog will also be disabled while Patroni is in paused state.
+Patroni will try to activate the watchdog before promoting PostgreSQL to primary. If watchdog activation fails and watchdog mode is ``required`` then the node will refuse to become leader. When deciding to participate in leader election Patroni will also check that watchdog configuration will allow it to become leader at all. After demoting PostgreSQL (for example due to a manual failover) Patroni will disable the watchdog again. Watchdog will also be disabled while Patroni is in paused state.
 
 By default Patroni will set up the watchdog to expire 5 seconds before TTL expires. With the default setup of ``loop_wait=10`` and ``ttl=30`` this gives HA loop at least 15 seconds (``ttl`` - ``safety_margin`` - ``loop_wait``) to complete before the system gets forcefully reset. By default accessing DCS is configured to time out after 10 seconds. This means that when DCS is unavailable, for example due to network issues, Patroni and PostgreSQL will have at least 5 seconds (``ttl`` - ``safety_margin`` - ``loop_wait`` - ``retry_timeout``) to come to a state where all client connections are terminated.
 

docs/yaml_configuration.rst

@@ -0,0 +1,373 @@
+.. _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
+---
+-  **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>` 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**: (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.
+   -  **users**: Some additional users which need to be created after initializing new cluster
+
+      -  **admin**: the name of user
+
+         -  **password**: (optional) password for the user
+         -  **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.
+
+.. _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]}``.
+
+.. 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.
+-  **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'
+
+.. _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.

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

@@ -16,16 +16,16 @@ listen stats
 	stats enable
 	stats uri /
 
-listen master
+listen primary
 	bind *:5000
-	option httpchk OPTIONS /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 $data.api_url "/") 2) ":") 1}}
 {{end}}
 listen replicas
 	bind *:5001
-	option httpchk OPTIONS /replica
+	option httpchk HEAD /replica
 	http-check expect status 200
 	default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions
 {{range gets "/members/*"}}	server {{base .Key}} {{$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:

extras/startup-scripts/patroni.service

@@ -14,7 +14,7 @@ Group=postgres
 # Read in configuration file if it exists, otherwise proceed
 EnvironmentFile=-/etc/patroni_env.conf
 
-# the default is the user's home directory, and if you want to change it, you must provide an absolute path.
+# The default is the user's home directory, and if you want to change it, you must provide an absolute path.
 # WorkingDirectory=/home/sameuser
 
 # Where to send early-startup messages from the server
@@ -32,14 +32,14 @@ ExecStart=/bin/patroni /etc/patroni.yml
 # Send HUP to reload from patroni.yml
 ExecReload=/bin/kill -s HUP $MAINPID
 
-# only kill the patroni process, not it's children, so it will gracefully stop postgres
+# Only kill the patroni process, not it's children, so it will gracefully stop postgres
 KillMode=process
 
 # Give a reasonable amount of time for the server to start up/shut down
 TimeoutSec=30
 
-# Do not restart the service if it crashes, we want to manually inspect database on failure
-Restart=no
+# Restart the service if it crashed
+Restart=on-failure
 
 [Install]
 WantedBy=multi-user.target

features/Dockerfile

@@ -0,0 +1,94 @@
+# 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-pip \
+      python3-dev \
+      rsync \
+      curl \
+      gcc \
+      golang \
+      jq  \
+      locales  \
+      sudo \
+      busybox \
+      net-tools \
+      iputils-ping \
+    && rm -rf /var/cache/apt \
+    && python3 -m pip install --no-cache-dir tox \
+    \
+    && 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-$(dpkg --print-architecture).tar.gz" \
+       | tar xz -C /usr/local/bin --strip=1 --wildcards --no-anchored etcd etcdctl
+
+
+# This Dockerfile syntax only works with docker buildx and the syntax
+# line at the top of this file.
+COPY <<EOF /tox-wrapper.sh
+#!/usr/bin/env bash
+set -ex
+copy_output() {
+    if [[ -d "\$PGHOME/src/features/output" && /src/features ]] ;then
+        cp -a "\$PGHOME/src/features/output" "/src/features/output-\$HOSTNAME"
+        find "/src/features/output-\$HOSTNAME" -type f -exec chmod 666 {} \\;
+        find "/src/features/output-\$HOSTNAME" -type d -exec chmod 777 {} \\;
+    fi
+}
+
+# Ensure the copy is ran if the container is stopped with `docker stop` or `docker kill`
+trap 'copy_output' SIGTERM
+# For architectures such as aarch we need to get the respective GOARCH
+# so we can tell etcd we're ok with running an unsupported architecture.
+export ETCD_UNSUPPORTED_ARCH=$(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/basic_replication.feature

@@ -5,7 +5,7 @@ Feature: basic replication
     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 {"ttl": 20, "loop_wait": 2, "synchronous_mode": true}
+    When I issue a PATCH request to http://127.0.0.1:8008/config with {"ttl": 20, "synchronous_mode": true}
     Then I receive a response code 200
     When I start postgres1
     And I configure and start postgres2 with a tag replicatefrom postgres0
@@ -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
@@ -77,6 +65,7 @@ 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
@@ -88,7 +77,7 @@ Feature: basic replication
     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

features/citus.feature

@@ -0,0 +1,72 @@
+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 worker in group 0
+    And postgres2 is registered in the postgres0 as the worker in group 1
+
+  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 replication works from postgres1 to postgres0 after 15 seconds
+    And "sync" key in a group 0 in DCS has sync_standby=postgres0 after 15 seconds
+    And postgres1 is registered in the postgres2 as the worker in group 0
+    When I run patronictl.py failover 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 "sync" key in a group 0 in DCS has sync_standby=postgres1 after 15 seconds
+    And postgres0 is registered in the postgres2 as the worker in group 0
+
+  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 replication works from postgres3 to postgres2 after 15 seconds
+    And "sync" key in a group 1 in DCS has sync_standby=postgres2 after 15 seconds
+    And postgres3 is registered in the postgres0 as the worker in group 1
+    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 "sync" key in a group 1 in DCS has sync_standby=postgres3 after 15 seconds
+    And postgres2 is registered in the postgres0 as the worker in group 1
+    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 worker in group 1
+    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"
+    When I sleep for 2 seconds
+    Then postgres4 is registered in the postgres2 as the worker in group 2
+    When I shut down postgres4
+    Then There is a transaction in progress on postgres0 changing pg_dist_node
+    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 +1,85 @@
+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
+    And I sleep for 3 seconds
+    When I issue a PATCH request to http://127.0.0.1:8008/config with {"loop_wait": 2, "ttl": 20, "retry_timeout": 5, "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"}}}
+    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
+    And I sleep for 2 seconds
+    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 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
+    And I get all changes from logical slot dcs_slot_0 on postgres0
+    And logical slot dcs_slot_0 is in sync between postgres0 and postgres1 after 20 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
+    And I sleep for 2 seconds
+    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 shut down 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: check three-node cluster is functioning while DCS is down
+    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
+    Given DCS is down
+    Then Response on GET http://127.0.0.1:8008/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

features/environment.py

@@ -1,11 +1,13 @@
 import abc
 import datetime
+import glob
 import os
-import psycopg2
 import json
+import psutil
+import re
 import shutil
 import signal
-import six
+import stat
 import subprocess
 import sys
 import tempfile
@@ -13,11 +15,13 @@ import threading
 import time
 import yaml
 
-from six.moves.BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
+import patroni.psycopg as psycopg
+
+from http.server import BaseHTTPRequestHandler, HTTPServer
+from patroni.request import PatroniRequest
 
 
-@six.add_metaclass(abc.ABCMeta)
-class AbstractController(object):
+class AbstractController(abc.ABC):
 
     def __init__(self, context, name, work_directory, output_dir):
         self._context = context
@@ -98,6 +102,7 @@ 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 = []
 
@@ -137,12 +142,24 @@ class PatroniController(AbstractController):
     def _start(self):
         if self.watchdog:
             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)
-            os.environ['PATRONI_KUBERNETES_POD_IP'] = '10.0.0.' + self._name[-1]
-        return subprocess.Popen([sys.executable, '-m', 'coverage', 'run',
-                                '--source=patroni', '-p', 'patroni.py', self._config],
-                                stdout=self._log, stderr=subprocess.STDOUT, cwd=self._work_directory)
+            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'
+        patroni = subprocess.Popen([sys.executable, '-m', 'coverage', 'run',
+                                   '--source=patroni', '-p', 'patroni.py', self._config], env=env,
+                                   stdout=self._log, stderr=subprocess.STDOUT, cwd=self._work_directory)
+        if os.name == 'nt':
+            patroni.terminate = self.terminate
+        return patroni
+
+    def terminate(self):
+        try:
+            self._context.request_executor.request('POST', self._restapi_url + '/sigterm')
+        except Exception:
+            pass
 
     def stop(self, kill=False, timeout=15, postgres=False):
         if postgres:
@@ -163,29 +180,61 @@ 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
+        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'  # windows doesn't yet support unix-domain sockets
-        config['postgresql']['pgpass'] = os.path.join(tempfile.gettempdir(), 'pgpass_' + name)
+        config['postgresql']['use_unix_socket_repl'] = os.name != 'nt'
+        config['postgresql']['pgpass'] = os.path.join(tempfile.gettempdir(), 'pgpass_' + name).replace('\\', '/')
         config['postgresql']['parameters'].update({
-            'logging_collector': 'on', 'log_destination': 'csvlog', 'log_directory': self._output_dir,
+            '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': self._data_dir})
+            '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"'
@@ -196,26 +245,43 @@ class PatroniController(AbstractController):
             self.recursive_update(config, custom_config)
 
         self.recursive_update(config, {
-            'bootstrap': {'dcs': {'postgresql': {'parameters': {'wal_keep_segments': 100}}}}})
+            '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, 'database': '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, 'database': '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 = psycopg2.connect(**self._connkwargs)
-            self._conn.autocommit = True
+            self._conn = psycopg.connect(**self._connkwargs)
         return self._conn
 
     def _cursor(self):
@@ -228,7 +294,7 @@ class PatroniController(AbstractController):
             cursor = self._cursor()
             cursor.execute(query)
             return cursor
-        except psycopg2.Error:
+        except psycopg.Error:
             if not fail_ok:
                 raise
 
@@ -268,7 +334,10 @@ class PatroniController(AbstractController):
 
     @property
     def backup_source(self):
-        return 'postgres://{username}:{password}@{host}:{port}/{database}'.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',
@@ -307,6 +376,7 @@ 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):
@@ -318,11 +388,22 @@ 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
@@ -356,8 +437,8 @@ 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)
@@ -370,11 +451,11 @@ 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):
@@ -393,8 +474,8 @@ class AbstractEtcdController(AbstractDcsController):
         self._client_cls = client_cls
 
     def _start(self):
-        return subprocess.Popen(["etcd", "--debug", "--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
@@ -414,10 +495,10 @@ 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
 
@@ -438,9 +519,9 @@ 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
 
@@ -451,7 +532,43 @@ 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)
@@ -460,19 +577,48 @@ 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)
@@ -489,12 +635,14 @@ 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:
+                if group is not None:
+                    scope = '{0}-{1}'.format(scope, group)
                 ep = scope + {'leader': '', 'history': '-config', 'initialize': '-config'}.get(key, '-' + key)
                 e = self._api.read_namespaced_endpoints(ep, self._namespace)
                 if key != 'sync':
@@ -519,11 +667,8 @@ 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 """
 
@@ -535,13 +680,13 @@ class ZooKeeperController(AbstractDcsController):
         import kazoo.client
         self._client = kazoo.client.KazooClient()
 
-    def _start(self):
-        pass  # TODO: implement later
+    def process_name(self):
+        return "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
 
@@ -555,6 +700,9 @@ 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
@@ -604,12 +752,12 @@ 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):
@@ -625,15 +773,18 @@ class RaftController(AbstractDcsController):
             self.start()
 
         ready_event = threading.Event()
-        self._raft = KVStoreTTL(ready_event.set, None, None, partner_addrs=[self.CONTROLLER_ADDR], password=self.PASSWORD)
+        self._raft = KVStoreTTL(ready_event.set, None, None,
+                                partner_addrs=[self.CONTROLLER_ADDR], password=self.PASSWORD)
         self._raft.startAutoTick()
         ready_event.wait()
 
 
 class PatroniPoolController(object):
 
-    BACKUP_SCRIPT = [sys.executable, 'features/backup_create.py']
-    ARCHIVE_RESTORE_SCRIPT = ' '.join((sys.executable, os.path.abspath('features/archive-restore.py')))
+    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):
         self._context = context
@@ -642,8 +793,17 @@ 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:
@@ -659,7 +819,7 @@ class PatroniPoolController(object):
     def output_dir(self):
         return self._output_dir
 
-    def start(self, name, max_wait_limit=20, custom_config=None):
+    def start(self, name, max_wait_limit=40, custom_config=None):
         if name not in self._processes:
             self._processes[name] = PatroniController(self._context, name, self.patroni_path,
                                                       self._output_dir, custom_config)
@@ -694,7 +854,8 @@ 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': {
@@ -707,9 +868,9 @@ 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'))
+                    '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'},
@@ -725,14 +886,14 @@ class PatroniPoolController(object):
             'bootstrap': {
                 'method': 'backup_restore',
                 'backup_restore': {
-                    'command': (sys.executable + ' features/backup_restore.py --sourcedir=' +
-                                os.path.join(self.patroni_path, 'data', 'basebackup')),
+                    'command': (self.BACKUP_RESTORE_SCRIPT + ' --sourcedir='
+                                + os.path.join(self.patroni_path, 'data', 'basebackup').replace('\\', '/')),
                     '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'))
+                        '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('\\', '/'))
                     }
                 }
             },
@@ -745,6 +906,25 @@ 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': {
+                    'command': (self.BACKUP_RESTORE_SCRIPT + ' --sourcedir='
+                                + os.path.join(self.patroni_path, 'data', 'basebackup').replace('\\', '/')),
+                    'no_leader': '1'
+                }
+            }
+        }
+        self.start(name, custom_config=custom_config)
+
     @property
     def dcs(self):
         if self._dcs is None:
@@ -871,10 +1051,34 @@ 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.ci = any(a in os.environ for a in ('TRAVIS_BUILD_NUMBER', 'BUILD_NUMBER', 'GITHUB_ACTIONS'))
+    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:
+        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'})
+        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:
@@ -892,13 +1096,45 @@ 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':
+        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()
-    shutil.rmtree(os.path.join(context.pctl.patroni_path, 'data'))
+    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):
+    if 'slot-advance' in scenario.effective_tags:
+        for p in context.pctl._processes.values():
+            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()))

features/ignored_slots.feature

@@ -3,14 +3,14 @@ Feature: ignored slots
     Given I start postgres1
     Then postgres1 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://127.0.0.1:8009/config with {"loop_wait": 2, "ignore_slots": [{"name": "unmanaged_slot_0", "database": "postgres", "plugin": "test_decoding", "type": "logical"}, {"name": "unmanaged_slot_1", "database": "postgres", "plugin": "test_decoding"}, {"name": "unmanaged_slot_2", "database": "postgres"}, {"name": "unmanaged_slot_3"}], "postgresql": {"parameters": {"wal_level": "logical"}}}
+    When I issue a PATCH request to http://127.0.0.1:8009/config with {"ignore_slots": [{"name": "unmanaged_slot_0", "database": "postgres", "plugin": "test_decoding", "type": "logical"}, {"name": "unmanaged_slot_1", "database": "postgres", "plugin": "test_decoding"}, {"name": "unmanaged_slot_2", "database": "postgres"}, {"name": "unmanaged_slot_3"}], "postgresql": {"parameters": {"wal_level": "logical"}}}
     Then I receive a response code 200
     And Response on GET http://127.0.0.1:8009/config contains ignore_slots after 10 seconds
     # Make sure the wal_level has been changed.
     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.
@@ -31,19 +31,19 @@ Feature: ignored slots
     And postgres1 has a logical replication slot named unmanaged_slot_3 with the test_decoding plugin
 
     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
@@ -52,9 +52,9 @@ Feature: ignored slots
     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
 
-    # 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
+    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
     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

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"
@@ -35,13 +35,13 @@ 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' -s 'loop_wait=2' -p 'max_connections=101' --force batman
+	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 "+loop_wait: 2"
+	And I receive a response output "+ttl: 10"
 	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 loop_wait 2
+	And I receive a response ttl 10
 	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'}
@@ -50,15 +50,15 @@ Scenario: check dynamic configuration change via DCS
 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 issue a scheduled restart at http://127.0.0.1:8008 in 3 seconds with {"role": "replica"}
+	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 4 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 3 seconds with {"restart_pending": "True"}
+	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
@@ -71,6 +71,7 @@ Scenario: check API requests for the primary-replica pair in the pause mode
 	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
+	And I sleep for 2 seconds
 	When I issue a GET request to http://127.0.0.1:8009/replica
 	Then I receive a response code 200
 	And I receive a response state running
@@ -78,12 +79,12 @@ Scenario: check API requests for the primary-replica pair in the pause mode
 	When I run patronictl.py reinit batman postgres1 --force
 	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"}
@@ -93,33 +94,33 @@ 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
 
 Scenario: check the scheduled switchover
-	Given I issue a scheduled switchover from postgres1 to postgres0 in 3 seconds
+	Given I issue a scheduled switchover from postgres1 to postgres0 in 10 seconds
 	Then I receive a response returncode 1
 	And I receive a response output "Can't schedule switchover in the paused state"
 	When I run patronictl.py resume batman
 	Then I receive a response returncode 0
-	Given I issue a scheduled switchover from postgres1 to postgres0 in 3 seconds
+	Given I issue a scheduled switchover from postgres1 to postgres0 in 10 seconds
 	Then I receive a response returncode 0
 	And postgres0 is a leader after 20 seconds
 	And postgres0 role is the primary after 10 seconds
 	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/standby_cluster.feature

@@ -3,7 +3,7 @@ Feature: standby cluster
     Given I start postgres1
     Then postgres1 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://127.0.0.1:8009/config with {"loop_wait": 2, "slots": {"pm_1": {"type": "physical"}}, "postgresql": {"parameters": {"wal_level": "logical"}}}
+    When I issue a PATCH request to http://127.0.0.1:8009/config with {"slots": {"pm_1": {"type": "physical"}}, "postgresql": {"parameters": {"wal_level": "logical"}}}
     Then I receive a response code 200
     And Response on GET http://127.0.0.1:8009/config contains slots after 10 seconds
     And I sleep for 3 seconds
@@ -14,7 +14,7 @@ Feature: standby cluster
     Then "members/postgres0" key in DCS has state=running after 10 seconds
     And replication works from postgres1 to postgres0 after 15 seconds
 
-  @skip
+  @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
@@ -35,7 +35,7 @@ Feature: standby cluster
     When I add the table foo to postgres0
     Then table foo is present on postgres1 after 20 seconds
     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
@@ -50,7 +50,7 @@ Feature: standby cluster
     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 issue a GET request to http://127.0.0.1:8010/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

features/steps/basic_replication.py

@@ -1,4 +1,4 @@
-import psycopg2 as pg
+import patroni.psycopg as pg
 
 from behave import step, then
 from time import sleep, time
@@ -28,7 +28,7 @@ def stop_postgres(context, name):
 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 +37,9 @@ 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 +47,10 @@ 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 +59,7 @@ 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)
 
@@ -68,7 +68,7 @@ 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:
@@ -83,10 +83,10 @@ def check_role(context, pg_name, pg_role, 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(int(time()), primary, replica, time_limit))

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')

features/steps/citus.py

@@ -0,0 +1,117 @@
+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 worker in group {group:d}')
+def check_registration(context, name1, name2, group):
+    worker_port = int(context.pctl.query(name1, "SHOW port").fetchone()[0])
+    r = context.pctl.query(name2, "SELECT nodeport FROM pg_catalog.pg_dist_node WHERE groupid = {0}".format(group))
+    assert worker_port == r.fetchone()[0],\
+        "Worker {0} is not registered in pg_dist_node on the coordinator {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")
+def check_transaction(context, name):
+    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'")
+    assert cur.rowcount == 1, "There is no idle in transaction updating pg_dist_node"
+    context.xact_start = cur.fetchone()[0]
+
+
+@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
@@ -10,10 +9,8 @@ import yaml
 from behave import register_type, step, then
 from dateutil import tz
 from datetime import datetime, timedelta
-from patroni.request import PatroniRequest
 
 tzutc = tz.tzutc()
-request_executor = PatroniRequest({'ctl': {'auth': 'username:password'}})
 
 
 @parse.with_pattern(r'https?://(?:\w|\.|:|/)+')
@@ -73,9 +70,13 @@ 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 = request_executor.request(request_method, url, data)
+        r = context.request_executor.request(request_method, url, data)
+        if request_method == 'PATCH' and r.status == 409:
+            r = context.request_executor.request(request_method, url, data)
     except Exception:
         context.status_code = context.response = None
     else:
@@ -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
@@ -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)
 
 
@@ -133,11 +133,27 @@ 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')
-def check_http_response(context, url, value, timeout, negate=False):
+@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 = request_executor.request('GET', url)
+        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)
         if (value in r.data.decode('utf-8')) != negate:
             break
         time.sleep(1)

features/steps/slots.py

@@ -1,7 +1,7 @@
 import time
-import psycopg2
 
 from behave import step, then
+import patroni.psycopg as pg
 
 
 @step('I create a logical replication slot {slot_name} on {pg_name:w} with the {plugin:w} plugin')
@@ -10,7 +10,7 @@ def create_logical_replication_slot(context, slot_name, pg_name, plugin):
         output = context.pctl.query(pg_name, ("SELECT pg_create_logical_replication_slot('{0}', '{1}'),"
                                               " current_database()").format(slot_name, plugin))
         print(output.fetchone())
-    except psycopg2.Error as e:
+    except pg.Error as e:
         print(e)
         assert False, "Error creating slot {0} on {1} with plugin {2}".format(slot_name, pg_name, plugin)
 
@@ -24,7 +24,7 @@ def has_logical_replication_slot(context, pg_name, slot_name, plugin):
         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 psycopg2.Error:
+    except pg.Error:
         assert False, "Error looking for slot {0} on {1} with plugin {2}".format(slot_name, pg_name, plugin)
 
 
@@ -34,7 +34,7 @@ def does_not_have_logical_replication_slot(context, pg_name, slot_name):
         row = context.pctl.query(pg_name, ("SELECT 1 FROM pg_replication_slots"
                                            " WHERE slot_name = '{0}'").format(slot_name)).fetchone()
         assert not row, "Found unexpected replication slot named {0}".format(slot_name)
-    except psycopg2.Error:
+    except pg.Error:
         assert False, "Error looking for slot {0} on {1}".format(slot_name, pg_name)
 
 

features/steps/standby_cluster.py

@@ -1,17 +1,12 @@
 import os
-import sys
 import time
 
 from behave import step
 
 
-select_replication_query = """
-SELECT * FROM pg_catalog.pg_stat_replication
-WHERE application_name = '{0}'
-"""
-
-executable = sys.executable if os.name != 'nt' else sys.executable.replace('\\', '/')
-callback = executable + " features/callback2.py "
+def callbacks(context, name):
+    return {c: '{0} features/callback2.py {1}'.format(context.pctl.PYTHON, name)
+            for c in ('on_start', 'on_stop', 'on_restart', 'on_role_change')}
 
 
 @step('I start {name:w} in a cluster {cluster_name:w}')
@@ -19,10 +14,10 @@ def start_patroni(context, name, cluster_name):
     return context.pctl.start(name, custom_config={
         "scope": cluster_name,
         "postgresql": {
-            "callbacks": {c: callback + name for c in ('on_start', 'on_stop', 'on_restart', 'on_role_change')},
+            "callbacks": callbacks(context, name),
             "backup_restore": {
-                "command": (executable + " features/backup_restore.py --sourcedir=" +
-                            os.path.join(context.pctl.patroni_path, 'data', 'basebackup'))}
+                "command": (context.pctl.PYTHON + " features/backup_restore.py --sourcedir="
+                            + os.path.join(context.pctl.patroni_path, 'data', 'basebackup').replace('\\', '/'))}
         }
     })
 
@@ -49,7 +44,7 @@ def start_patroni_standby_cluster(context, name, cluster_name, name2):
             }
         },
         "postgresql": {
-            "callbacks": {c: callback + name for c in ('on_start', 'on_stop', 'on_restart', 'on_role_change')}
+            "callbacks": callbacks(context, name)
         }
     })
     return context.pctl.start(name)
@@ -57,12 +52,12 @@ def start_patroni_standby_cluster(context, name, cluster_name, name2):
 
 @step('{pg_name1:w} is replicating from {pg_name2:w} after {timeout:d} seconds')
 def check_replication_status(context, pg_name1, pg_name2, timeout):
-    bound_time = time.time() + timeout
+    bound_time = time.time() + timeout * context.timeout_multiplier
 
     while time.time() < bound_time:
         cur = context.pctl.query(
             pg_name2,
-            select_replication_query.format(pg_name1),
+            "SELECT * FROM pg_catalog.pg_stat_replication WHERE application_name = '{0}'".format(pg_name1),
             fail_ok=True
         )
 

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

@@ -1,10 +1,9 @@
-FROM postgres:11
-MAINTAINER Alexander Kukushkin <alexander.kukushkin@zalando.de>
+FROM postgres:15
+LABEL maintainer="Alexander Kukushkin <akukushkin@microsoft.com>"
 
 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 \
@@ -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 +1,46 @@
+FROM postgres:15
+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 \
+    && 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-11.3 \
+    && pip3 install setuptools \
+    && pip3 install '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 \
+    && 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.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-from patroni import main
+from patroni.__main__ import main
 
 
 if __name__ == '__main__':

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

@@ -1,206 +1,94 @@
-import logging
-import os
-import signal
+"""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.
+"""
+
 import sys
-import time
 
-from .daemon import AbstractPatroniDaemon, abstract_main
-from .version import __version__
-
-logger = logging.getLogger(__name__)
+from typing import Any, Callable, Iterator, Tuple
 
 PATRONI_ENV_PREFIX = 'PATRONI_'
 KUBERNETES_ENV_PREFIX = 'KUBERNETES_'
+MIN_PSYCOPG2 = (2, 5, 4)
 
 
-class Patroni(AbstractPatroniDaemon):
+def fatal(string: str, *args: Any) -> None:
+    """Write a fatal message to stderr and exit with code ``1``.
 
-    def __init__(self, config):
-        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.watchdog import Watchdog
-
-        super(Patroni, self).__init__(config)
-
-        self.version = __version__
-        self.dcs = get_dcs(self.config)
-        self.watchdog = Watchdog(self.config)
-        self.load_dynamic_configuration()
-
-        self.postgresql = Postgresql(self.config['postgresql'])
-        self.api = RestApiServer(self, self.config['restapi'])
-        self.request = PatroniRequest(self.config, True)
-        self.ha = Ha(self)
-
-        self.tags = self.get_tags()
-        self.next_run = time.time()
-        self.scheduled_restart = {}
-
-    def load_dynamic_configuration(self):
-        from patroni.exceptions import DCSError
-        while True:
-            try:
-                cluster = self.dcs.get_cluster()
-                if cluster and cluster.config and cluster.config.data:
-                    if self.config.set_dynamic_configuration(cluster.config):
-                        self.dcs.reload_config(self.config)
-                        self.watchdog.reload_config(self.config)
-                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)
-                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}
-
-    @property
-    def nofailover(self):
-        return bool(self.tags.get('nofailover', False))
-
-    @property
-    def nosync(self):
-        return bool(self.tags.get('nosync', False))
-
-    def reload_config(self, sighup=False, local=False):
-        try:
-            super(Patroni, self).reload_config(sighup, local)
-            if local:
-                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'])
-            self.watchdog.reload_config(self.config)
-            self.postgresql.reload_config(self.config['postgresql'], sighup)
-            self.dcs.reload_config(self.config)
-        except Exception:
-            logger.exception('Failed to reload config_file=%s', self.config.config_file)
-
-    @property
-    def replicatefrom(self):
-        return self.tags.get('replicatefrom')
-
-    @property
-    def noloadbalance(self):
-        return bool(self.tags.get('noloadbalance', False))
-
-    def schedule_next_run(self):
-        self.next_run += self.dcs.loop_wait
-        current_time = time.time()
-        nap_time = self.next_run - current_time
-        if nap_time <= 0:
-            self.next_run = current_time
-            # Release the GIL so we don't starve anyone waiting on async_executor lock
-            time.sleep(0.001)
-            # Warn user that Patroni is not keeping up
-            logger.warning("Loop time exceeded, rescheduling immediately.")
-        elif self.ha.watch(nap_time):
-            self.next_run = time.time()
-
-    def run(self):
-        self.api.start()
-        self.next_run = time.time()
-        super(Patroni, self).run()
-
-    def _run_cycle(self):
-        logger.info(self.ha.run_cycle())
-
-        if self.dcs.cluster and self.dcs.cluster.config and self.dcs.cluster.config.data \
-                and self.config.set_dynamic_configuration(self.dcs.cluster.config):
-            self.reload_config()
-
-        if self.postgresql.role != 'uninitialized':
-            self.config.save_cache()
-
-        self.schedule_next_run()
-
-    def _shutdown(self):
-        try:
-            self.api.shutdown()
-        except Exception:
-            logger.exception('Exception during RestApi.shutdown')
-        try:
-            self.ha.shutdown()
-        except Exception:
-            logger.exception('Exception during Ha.shutdown')
+    :param string: message to be written before exiting.
+    """
+    sys.exit('FATAL: ' + string.format(*args))
 
 
-def patroni_main():
-    from multiprocessing import freeze_support
-    from patroni.validator import schema
+def parse_version(version: str) -> Tuple[int, ...]:
+    """Convert *version* from human-readable format to tuple of integers.
 
-    freeze_support()
-    abstract_main(Patroni, schema)
+    .. note::
+        Designed for easy comparison of software versions in Python.
 
+    :param version: human-readable software version, e.g. ``2.5.4``.
 
-def fatal(string, *args):
-    sys.stderr.write('FATAL: ' + string.format(*args) + '\n')
-    sys.exit(1)
+    :returns: tuple of *version* parts, each part as an integer.
 
+    :Example:
 
-def check_psycopg2():
-    min_psycopg2 = (2, 5, 4)
-    min_psycopg2_str = '.'.join(map(str, min_psycopg2))
+        >>> parse_version('2.5.4')
+        (2, 5, 4)
+    """
+    def _parse_version(version: str) -> Iterator[int]:
+        """Yield each part of a human-readable version string as an integer.
 
-    def parse_version(version):
+        :param version: human-readable software version, e.g. ``2.5.4``.
+
+        :yields: each part of *version* as an integer.
+
+        :Example:
+
+            >>> tuple(_parse_version('2.5.4'))
+            (2, 5, 4)
+        """
         for e in version.split('.'):
             try:
                 yield int(e)
             except ValueError:
                 break
+    return tuple(_parse_version(version.split(' ')[0]))
 
+
+def check_psycopg(_min_psycopg2: Tuple[int, ...] = MIN_PSYCOPG2,
+                  _parse_version: Callable[[str], Tuple[int, ...]] = parse_version) -> None:
+    """Ensure at least one among :mod:`psycopg2` or :mod:`psycopg` libraries are available in the environment.
+
+    .. note::
+        We pass ``MIN_PSYCOPG2`` and :func:`parse_version` as arguments to simplify usage of :func:`check_psycopg` from
+        the ``setup.py``.
+
+    .. note::
+        Patroni chooses :mod:`psycopg2` over :mod:`psycopg`, if possible.
+
+        If nothing meeting the requirements is found, then exit with a fatal message.
+
+    :param _min_psycopg2: minimum required version in case :mod:`psycopg2` is chosen.
+    :param _parse_version: function used to parse :mod:`psycopg2`/:mod:`psycopg` version into a comparable object.
+    """
+    min_psycopg2_str = '.'.join(map(str, _min_psycopg2))
+
+    # try psycopg2
     try:
-        import psycopg2
-        version_str = psycopg2.__version__.split(' ')[0]
-        version = tuple(parse_version(version_str))
-        if version < min_psycopg2:
-            fatal('Patroni requires psycopg2>={0}, but only {1} is available', min_psycopg2_str, version_str)
+        from psycopg2 import __version__
+        if _parse_version(__version__) >= _min_psycopg2:
+            return
+        version_str = __version__.split(' ')[0]
     except ImportError:
-        fatal('Patroni requires psycopg2>={0} or psycopg2-binary', min_psycopg2_str)
+        version_str = None
 
-
-def main():
-    if os.getpid() != 1:
-        check_psycopg2()
-        return patroni_main()
-
-    # Patroni started with PID=1, it looks like we are in the container
-    pid = 0
-
-    # Looks like we are in a docker, so we will act like init
-    def sigchld_handler(signo, stack_frame):
-        try:
-            while True:
-                ret = os.waitpid(-1, os.WNOHANG)
-                if ret == (0, 0):
-                    break
-                elif ret[0] != pid:
-                    logger.info('Reaped pid=%s, exit status=%s', *ret)
-        except OSError:
-            pass
-
-    def passtochild(signo, stack_frame):
-        if pid:
-            os.kill(pid, signo)
-
-    if os.name != 'nt':
-        signal.signal(signal.SIGCHLD, sigchld_handler)
-        signal.signal(signal.SIGHUP, passtochild)
-        signal.signal(signal.SIGQUIT, passtochild)
-        signal.signal(signal.SIGUSR1, passtochild)
-        signal.signal(signal.SIGUSR2, passtochild)
-    signal.signal(signal.SIGINT, passtochild)
-    signal.signal(signal.SIGABRT, passtochild)
-    signal.signal(signal.SIGTERM, passtochild)
-
-    import multiprocessing
-    patroni = multiprocessing.Process(target=patroni_main)
-    patroni.start()
-    pid = patroni.pid
-    patroni.join()
+    # try psycopg3
+    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 is not None:
+            error += ', but only psycopg2=={0} is available'.format(version_str)
+        fatal(error)

patroni/__main__.py

@@ -1,4 +1,210 @@
-from patroni import main
+import logging
+import os
+import signal
+import sys
+import time
+
+from argparse import Namespace
+from typing import Any, Dict, Optional, TYPE_CHECKING
+
+from patroni.daemon import AbstractPatroniDaemon, abstract_main, get_base_arg_parser
+
+if TYPE_CHECKING:  # pragma: no cover
+    from .config import Config
+
+logger = logging.getLogger(__name__)
+
+
+class Patroni(AbstractPatroniDaemon):
+
+    def __init__(self, config: 'Config') -> None:
+        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.watchdog = Watchdog(self.config)
+        self.load_dynamic_configuration()
+
+        self.postgresql = Postgresql(self.config['postgresql'])
+        self.api = RestApiServer(self, self.config['restapi'])
+        self.request = PatroniRequest(self.config, True)
+        self.ha = Ha(self)
+
+        self.tags = self.get_tags()
+        self.next_run = time.time()
+        self.scheduled_restart: Dict[str, Any] = {}
+
+    def load_dynamic_configuration(self) -> None:
+        from patroni.exceptions import DCSError
+        while True:
+            try:
+                cluster = self.dcs.get_cluster()
+                if cluster and cluster.config and cluster.config.data:
+                    if self.config.set_dynamic_configuration(cluster.config):
+                        self.dcs.reload_config(self.config)
+                        self.watchdog.reload_config(self.config)
+                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) -> Dict[str, Any]:
+        return {tag: value for tag, value in self.config.get('tags', {}).items()
+                if tag not in ('clonefrom', 'nofailover', 'noloadbalance', 'nosync') or value}
+
+    @property
+    def nofailover(self) -> bool:
+        return bool(self.tags.get('nofailover', False))
+
+    @property
+    def nosync(self) -> bool:
+        return bool(self.tags.get('nosync', False))
+
+    def reload_config(self, sighup: bool = False, local: Optional[bool] = False) -> None:
+        try:
+            super(Patroni, self).reload_config(sighup, local)
+            if local:
+                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'])
+            self.watchdog.reload_config(self.config)
+            self.postgresql.reload_config(self.config['postgresql'], sighup)
+            self.dcs.reload_config(self.config)
+        except Exception:
+            logger.exception('Failed to reload config_file=%s', self.config.config_file)
+
+    @property
+    def replicatefrom(self):
+        return self.tags.get('replicatefrom')
+
+    @property
+    def noloadbalance(self):
+        return bool(self.tags.get('noloadbalance', False))
+
+    def schedule_next_run(self) -> None:
+        self.next_run += self.dcs.loop_wait
+        current_time = time.time()
+        nap_time = self.next_run - current_time
+        if nap_time <= 0:
+            self.next_run = current_time
+            # Release the GIL so we don't starve anyone waiting on async_executor lock
+            time.sleep(0.001)
+            # Warn user that Patroni is not keeping up
+            logger.warning("Loop time exceeded, rescheduling immediately.")
+        elif self.ha.watch(nap_time):
+            self.next_run = time.time()
+
+    def run(self) -> None:
+        self.api.start()
+        self.next_run = time.time()
+        super(Patroni, self).run()
+
+    def _run_cycle(self) -> None:
+        logger.info(self.ha.run_cycle())
+
+        if self.dcs.cluster and self.dcs.cluster.config and self.dcs.cluster.config.data \
+                and self.config.set_dynamic_configuration(self.dcs.cluster.config):
+            self.reload_config()
+
+        if self.postgresql.role != 'uninitialized':
+            self.config.save_cache()
+
+        self.schedule_next_run()
+
+    def _shutdown(self) -> None:
+        try:
+            self.api.shutdown()
+        except Exception:
+            logger.exception('Exception during RestApi.shutdown')
+        try:
+            self.ha.shutdown()
+        except Exception:
+            logger.exception('Exception during Ha.shutdown')
+
+
+def patroni_main(configfile: str) -> None:
+    from multiprocessing import freeze_support
+
+    freeze_support()
+    abstract_main(Patroni, configfile)
+
+
+def process_arguments() -> Namespace:
+    parser = get_base_arg_parser()
+    parser.add_argument('--validate-config', action='store_true', help='Run config validator and exit')
+    args = parser.parse_args()
+
+    if 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 main() -> None:
+    from patroni import check_psycopg
+
+    args = process_arguments()
+
+    check_psycopg()
+
+    if os.getpid() != 1:
+        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: int, stack_frame: Optional[FrameType]) -> None:
+        try:
+            while True:
+                ret = os.waitpid(-1, os.WNOHANG)
+                if ret == (0, 0):
+                    break
+                elif ret[0] != pid:
+                    logger.info('Reaped pid=%s, exit status=%s', *ret)
+        except OSError:
+            pass
+
+    def passtochild(signo: int, stack_frame: Optional[FrameType]):
+        if pid:
+            os.kill(pid, signo)
+
+    if os.name != 'nt':
+        signal.signal(signal.SIGCHLD, sigchld_handler)
+        signal.signal(signal.SIGHUP, passtochild)
+        signal.signal(signal.SIGQUIT, passtochild)
+        signal.signal(signal.SIGUSR1, passtochild)
+        signal.signal(signal.SIGUSR2, passtochild)
+    signal.signal(signal.SIGINT, passtochild)
+    signal.signal(signal.SIGABRT, passtochild)
+    signal.signal(signal.SIGTERM, passtochild)
+
+    import multiprocessing
+    patroni = multiprocessing.Process(target=patroni_main, args=(args.configfile,))
+    patroni.start()
+    pid = patroni.pid
+    patroni.join()
 
 
 if __name__ == '__main__':

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 +1,202 @@
+"""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, 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 __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

@@ -7,11 +7,14 @@ 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, Cluster
+from .exceptions import ConfigParseError
+from .postgresql.config import ConfigHandler
+from .utils import deep_compare, parse_bool, parse_int, patch_config
 
 logger = logging.getLogger(__name__)
 
@@ -24,14 +27,135 @@ _AUTH_ALLOWED_PARAMETERS = (
     'sslpassword',
     'sslrootcert',
     'sslcrl',
+    'sslcrldir',
     'gssencmode',
     'channel_binding'
 )
 
 
-def default_validator(conf):
+def default_validator(conf: Dict[str, Any]) -> List[str]:
     if not conf:
-        return "Config is empty."
+        raise ConfigParseError("Config is empty.")
+    return []
+
+
+class GlobalConfig(object):
+
+    """A class that wrapps global configuration and provides convinient methods to access/check values.
+
+    It is instantiated by calling :func:`Config.global_config` method which picks either a
+    configuration from provided :class:`Cluster` object (the most up-to-date) or from the
+    local cache if :class::`ClusterConfig` is not initialized or doesn't have a valid config.
+    """
+
+    def __init__(self, config: Dict[str, Any]) -> None:
+        """Initialize :class:`GlobalConfig` object.
+
+        :param config: current configuration either from
+                       :class:`ClusterConfig` or from :class:`Config.dynamic_configuration`
+        """
+        self.__config = config
+
+    def get(self, name: str) -> Any:
+        """Gets global configuration value by name.
+
+        :param name: parameter name
+        :returns: configuration value or `None` if it is missing
+        """
+        return self.__config.get(name)
+
+    def check_mode(self, mode: str) -> bool:
+        """Checks whether the certain parameter is enabled.
+
+        :param mode: parameter name could be: synchronous_mode, failsafe_mode, pause, check_timeline, and so on
+        :returns: `True` if *mode* is enabled in the global configuration.
+        """
+        return bool(parse_bool(self.__config.get(mode)))
+
+    @property
+    def is_paused(self) -> bool:
+        """:returns: `True` if cluster is in maintenance mode."""
+        return self.check_mode('pause')
+
+    @property
+    def is_synchronous_mode(self) -> bool:
+        """:returns: `True` if synchronous replication is requested."""
+        return self.check_mode('synchronous_mode')
+
+    @property
+    def is_synchronous_mode_strict(self) -> bool:
+        """:returns: `True` if at least one synchronous node is required."""
+        return self.check_mode('synchronous_mode_strict')
+
+    def get_standby_cluster_config(self) -> Union[Dict[str, Any], Any]:
+        """:returns: "standby_cluster" configuration."""
+        return deepcopy(self.get('standby_cluster'))
+
+    @property
+    def is_standby_cluster(self) -> bool:
+        """:returns: `True` if global configuration has a valid "standby_cluster" section."""
+        config = self.get_standby_cluster_config()
+        return isinstance(config, dict) and\
+            bool(config.get('host') or config.get('port') or config.get('restore_command'))
+
+    def get_int(self, name: str, default: int = 0) -> int:
+        """Gets current value from the global configuration and trying to return it as int.
+
+        :param name: name of the parameter
+        :param default: default value if *name* is not in the configuration or invalid
+        :returns: currently configured value from the global configuration or *default* if it is not set or invalid.
+        """
+        ret = parse_int(self.get(name))
+        return default if ret is None else ret
+
+    @property
+    def min_synchronous_nodes(self) -> int:
+        """:returns: the minimal number of synchronous nodes based on whether strict mode is requested or not."""
+        return 1 if self.is_synchronous_mode_strict else 0
+
+    @property
+    def synchronous_node_count(self) -> int:
+        """:returns: currently configured value from the global configuration or 1 if it is not set or invalid."""
+        return max(self.get_int('synchronous_node_count', 1), self.min_synchronous_nodes)
+
+    @property
+    def maximum_lag_on_failover(self) -> int:
+        """:returns: currently configured value from the global configuration or 1048576 if it is not set or invalid."""
+        return self.get_int('maximum_lag_on_failover', 1048576)
+
+    @property
+    def maximum_lag_on_syncnode(self) -> int:
+        """:returns: currently configured value from the global configuration or -1 if it is not set or invalid."""
+        return self.get_int('maximum_lag_on_syncnode', -1)
+
+    @property
+    def primary_start_timeout(self) -> int:
+        """:returns: currently configured value from the global configuration or 300 if it is not set or invalid."""
+        default = 300
+        return self.get_int('primary_start_timeout', default)\
+            if 'primary_start_timeout' in self.__config else self.get_int('master_start_timeout', default)
+
+    @property
+    def primary_stop_timeout(self) -> int:
+        """:returns: currently configured value from the global configuration or 300 if it is not set or invalid."""
+        default = 0
+        return self.get_int('primary_stop_timeout', default)\
+            if 'primary_stop_timeout' in self.__config else self.get_int('master_stop_timeout', default)
+
+
+def get_global_config(cluster: Union[Cluster, None], default: Optional[Dict[str, Any]] = None) -> GlobalConfig:
+    """Instantiates :class:`GlobalConfig` based on the input.
+
+    :param cluster: the currently known cluster state from DCS
+    :param default: default configuration, which will be used if there is no valid *cluster.config*
+    :returns: :class:`GlobalConfig` object
+    """
+    # Try to protect from the case when DCS was wiped out
+    if cluster and cluster.config and cluster.config.modify_version:
+        config = cluster.config.data
+    else:
+        config = default or {}
+    return GlobalConfig(deepcopy(config))
 
 
 class Config(object):
@@ -57,16 +181,8 @@ class Config(object):
     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': '',
@@ -81,29 +197,28 @@ class Config(object):
             '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',
         }
     }
 
-    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:
+        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:
-            error = validator(self._local_configuration)
-            if error:
-                raise ConfigParseError(error)
+            errors = validator(self._local_configuration)
+            if errors:
+                raise ConfigParseError("\n".join(errors))
 
         self.__effective_configuration = self._build_effective_configuration({}, self._local_configuration)
         self._data_dir = self.__effective_configuration.get('postgresql', {}).get('data_dir', "")
@@ -112,17 +227,14 @@ class Config(object):
         self._cache_needs_saving = False
 
     @property
-    def config_file(self):
+    def config_file(self) -> Union[str, None]:
         return self._config_file
 
     @property
-    def dynamic_configuration(self):
+    def dynamic_configuration(self) -> Dict[str, Any]:
         return deepcopy(self._dynamic_configuration)
 
-    def check_mode(self, mode):
-        return bool(parse_bool(self._dynamic_configuration.get(mode)))
-
-    def _load_config_path(self, path):
+    def _load_config_path(self, path: str) -> Dict[str, Any]:
         """
         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
@@ -136,20 +248,22 @@ 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):
+    def _load_config_file(self) -> Dict[str, Any]:
         """Loads config.yaml from filesystem and applies some values which were set via ENV"""
+        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:
         if os.path.isfile(self._cache_file):
             try:
                 with open(self._cache_file) as f:
@@ -157,7 +271,7 @@ class Config(object):
             except Exception:
                 logger.exception('Exception when loading file: %s', self._cache_file)
 
-    def save_cache(self):
+    def save_cache(self) -> None:
         if self._cache_needs_saving:
             tmpfile = fd = None
             try:
@@ -181,11 +295,11 @@ class Config(object):
                         logger.error('Can not remove temporary file %s', tmpfile)
 
     # 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:
         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 changed there is nothing to do
+            self._modify_version = configuration.modify_version
             configuration = configuration.data
 
         if not deep_compare(self._dynamic_configuration, configuration):
@@ -197,8 +311,9 @@ 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]:
         if self.config_file:
             try:
                 configuration = self._load_config_file()
@@ -213,12 +328,12 @@ class Config(object):
                 logger.exception('Exception when reloading local configuration from %s', self.config_file)
 
     @staticmethod
-    def _process_postgresql_parameters(parameters, is_local=False):
+    def _process_postgresql_parameters(parameters: Dict[str, Any], is_local: bool = False) -> Dict[str, Any]:
         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)}
+                if name not in ConfigHandler.CMDLINE_OPTIONS
+                or not is_local and ConfigHandler.CMDLINE_OPTIONS[name][1](value)}
 
-    def _safe_copy_dynamic_configuration(self, dynamic_configuration):
+    def _safe_copy_dynamic_configuration(self, dynamic_configuration: Dict[str, Any]) -> Dict[str, Any]:
         config = deepcopy(self.__DEFAULT_CONFIG)
 
         for name, value in dynamic_configuration.items():
@@ -226,24 +341,22 @@ class Config(object):
                 for name, value in (value or {}).items():
                     if name == 'parameters':
                         config['postgresql'][name].update(self._process_postgresql_parameters(value))
-                    elif name not in ('connect_address', 'listen', 'data_dir', 'pgpass', 'authentication'):
+                    elif name not in ('connect_address', 'proxy_address', 'listen',
+                                      'config_dir', 'data_dir', 'pgpass', 'authentication'):
                         config['postgresql'][name] = deepcopy(value)
             elif name == 'standby_cluster':
                 for name, value in (value or {}).items():
                     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]:
+        ret: Dict[str, Any] = defaultdict(dict)
 
-        def _popenv(name):
+        def _popenv(name: str) -> Union[str, None]:
             return os.environ.pop(PATRONI_ENV_PREFIX + name.upper(), None)
 
         for param in ('name', 'namespace', 'scope'):
@@ -251,7 +364,7 @@ class Config(object):
             if value:
                 ret[param] = value
 
-        def _fix_log_env(name, oldname):
+        def _fix_log_env(name: str, oldname: str) -> None:
             value = _popenv(oldname)
             name = PATRONI_ENV_PREFIX + 'LOG_' + name.upper()
             if value and name not in os.environ:
@@ -260,7 +373,7 @@ 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:
             for param in params:
                 value = _popenv(section + '_' + param)
                 if value:
@@ -268,13 +381,20 @@ 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'])
-        _set_section_values('ctl', ['insecure', 'cacert', 'certfile', 'keyfile'])
-        _set_section_values('postgresql', ['listen', 'connect_address', 'config_dir', 'data_dir', 'pgpass', 'bin_dir'])
+                                        '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('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
+
         for first, second in (('restapi', 'allowlist_include_members'), ('ctl', 'insecure')):
             value = ret.get(first, {}).pop(second, None)
             if value:
@@ -282,14 +402,16 @@ 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) -> Union[List[str], None]:
             if not (value.strip().startswith('-') or '[' in value):
                 value = '[{0}]'.format(value)
             try:
@@ -305,7 +427,7 @@ class Config(object):
                 if value:
                     ret[first][second] = value
 
-        def _parse_dict(value):
+        def _parse_dict(value: str) -> Union[Dict[str, Any], None]:
             if not value.strip().startswith('{'):
                 value = '{{{0}}}'.format(value)
             try:
@@ -322,8 +444,8 @@ class Config(object):
                     if value:
                         ret[first][second] = value
 
-        def _get_auth(name, params=None):
-            ret = {}
+        def _get_auth(name: str, params: Optional[Collection[str]] = None) -> Dict[str, str]:
+            ret: Dict[str, str] = {}
             for param in params or _AUTH_ALLOWED_PARAMETERS[:2]:
                 value = _popenv(name + '_' + param)
                 if value:
@@ -349,19 +471,25 @@ class Config(object):
                 name, suffix = (param[8:].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', 'NAMESPACE', 'CONTEXT',
-                              'USE_ENDPOINTS', 'SCOPE_LABEL', 'ROLE_LABEL', 'POD_IP', 'PORTS', 'LABELS',
-                              'BYPASS_API_SERVICE', 'KEY_PASSWORD', 'USE_SSL') and name:
+                              'REGISTER_SERVICE', 'SERVICE_CHECK_INTERVAL', 'SERVICE_CHECK_TLS_SERVER_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') 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 == 'LABELS':
+                    elif suffix in ('LABELS', 'SET_ACLS'):
                         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:
@@ -386,10 +514,15 @@ 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]:
         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))
@@ -427,28 +560,41 @@ 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:
         return self.__effective_configuration.get(key, default)
 
-    def __contains__(self, key):
+    def __contains__(self, key: str) -> bool:
         return key in self.__effective_configuration
 
-    def __getitem__(self, key):
+    def __getitem__(self, key: str) -> Any:
         return self.__effective_configuration[key]
 
-    def copy(self):
+    def copy(self) -> Dict[str, Any]:
         return deepcopy(self.__effective_configuration)
+
+    def get_global_config(self, cluster: Union[Cluster, None]) -> GlobalConfig:
+        """Instantiate :class:`GlobalConfig` based on input.
+
+        Use the configuration from provided *cluster* (the most up-to-date) or from the
+        local cache if *cluster.config* is not initialized or doesn't have a valid config.
+        :param cluster: the currently known cluster state from DCS
+        :returns: :class:`GlobalConfig` object
+        """
+        return get_global_config(cluster, self._dynamic_configuration)

patroni/daemon.py

@@ -1,16 +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()
@@ -19,16 +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 sigterm_handler(self, *args):
+    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
-                sys.exit()
+                ret = True
+        return ret
 
-    def setup_signal_handlers(self):
+    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) -> 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
@@ -37,19 +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:
@@ -59,41 +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()
     try:
-        if validator and args.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)
-        parser.print_help()
-        sys.exit(1)
+        sys.exit(e.value)
 
     controller = cls(config)
     try:

patroni/dcs/consul.py

@@ -8,15 +8,19 @@ 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, SyncState,\
+    TimelineHistory, ReturnFalseException, catch_return_false_exception, citus_group_re
 from ..exceptions import DCSError
 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 +41,17 @@ class InvalidSession(ConsulException):
     """invalid session"""
 
 
-Response = namedtuple('Response', 'code,headers,body,content')
+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 +67,23 @@ 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 +96,19 @@ 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 +119,14 @@ 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 +140,13 @@ class HTTPClient(object):
 
 class ConsulClient(base.Consul):
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
         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 +156,17 @@ 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 +174,25 @@ 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 +202,9 @@ def service_name_from_scope_name(scope_name):
 
 class Consul(AbstractDCS):
 
-    def __init__(self, config):
+    def __init__(self, config: Dict[str, Any]) -> None:
         super(Consul, self).__init__(config)
+        self._base_path = self._base_path[1:]
         self._scope = config['scope']
         self._session = None
         self.__do_not_watch = False
@@ -196,9 +212,9 @@ 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 +229,7 @@ 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):
@@ -233,13 +249,15 @@ class Consul(AbstractDCS):
         if self._register_service:
             self._set_service_name()
         self._service_check_interval = config.get('service_check_interval', '5s')
+        self._service_check_tls_server_name = config.get('service_check_tls_server_name', None)
         if not self._ctl:
             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()
@@ -247,13 +265,14 @@ 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:
@@ -262,31 +281,32 @@ 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:
@@ -308,103 +328,117 @@ 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):
-        try:
-            path = self.client_path('/')
-            _, results = self.retry(self._client.kv.get, path, recurse=True)
+    def _cluster_from_nodes(self, nodes: Dict[str, Any]) -> Cluster:
+        # get initialize flag
+        initialize = nodes.get(self._INITIALIZE)
+        initialize = initialize and initialize['Value']
 
-            if results is None:
-                raise NotFound
+        # get global dynamic configuration
+        config = nodes.get(self._CONFIG)
+        config = config and ClusterConfig.from_node(config['ModifyIndex'], config['Value'])
 
-            nodes = {}
-            for node in results:
-                node['Value'] = (node['Value'] or b'').decode('utf-8')
-                nodes[node['Key'][len(path):].lstrip('/')] = node
-
-            # 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
+        # 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:
-                last_lsn = int(last_lsn)
+                status = json.loads(status['Value'])
+                last_lsn = status.get(self._OPTIME)
+                slots = status.get('slots')
             except Exception:
-                last_lsn = 0
+                slots = last_lsn = None
+        else:
+            last_lsn = nodes.get(self._LEADER_OPTIME)
+            last_lsn = last_lsn and last_lsn['Value']
+            slots = None
 
-            # get list of members
-            members = [self.member(n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
+        try:
+            last_lsn = int(last_lsn or '')
+        except Exception:
+            last_lsn = 0
 
-            # 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
+        # get list of members
+        members = [self.member(n) for k, n in nodes.items() if k.startswith(self._MEMBERS) and k.count('/') == 1]
 
-            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)
+        # get leader
+        leader = nodes.get(self._LEADER)
 
-            # failover key
-            failover = nodes.get(self._FAILOVER)
-            if failover:
-                failover = Failover.from_node(failover['ModifyIndex'], failover['Value'])
+        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)
 
-            # get synchronization state
-            sync = nodes.get(self._SYNC)
-            sync = SyncState.from_node(sync and sync['ModifyIndex'], sync and sync['Value'])
+        # failover key
+        failover = nodes.get(self._FAILOVER)
+        if failover:
+            failover = Failover.from_node(failover['ModifyIndex'], failover['Value'])
 
-            return Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots)
+        # 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:
+            failsafe = json.loads(failsafe['Value']) if failsafe else None
+        except Exception:
+            failsafe = None
+
+        return Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots, failsafe)
+
+    def _cluster_loader(self, path: str) -> Cluster:
+        _, results = self.retry(self._client.kv.get, path, recurse=True)
+        if results is None:
+            raise NotFound
+        nodes = {}
+        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 _citus_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        _, results = self.retry(self._client.kv.get, path, recurse=True)
+        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 citus_group_re.match(key[0]):
+                node['Value'] = (node['Value'] or b'').decode('utf-8')
+                clusters[int(key[0])][key[1]] = node
+        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]]:
+        try:
+            return loader(path)
         except NotFound:
-            return Cluster(None, None, None, None, [], None, None, None, None)
+            return Cluster.empty()
         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
 
@@ -422,8 +456,7 @@ 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
@@ -432,35 +465,44 @@ 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)
 
     @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)
 
-    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
 
         params = {
             'service_id': '{0}/{1}'.format(self._scope, self._name),
@@ -476,7 +518,7 @@ 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)
@@ -484,7 +526,7 @@ 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']:
@@ -497,99 +539,141 @@ class Consul(AbstractDCS):
         if (
             force or update or self._register_service != self._previous_loop_register_service
             or self._service_tags != self._previous_loop_service_tags
+            or self._client.token != self._previous_loop_token
         ):
             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):
+    def _delete_leader(self) -> bool:
         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)
+        if cluster and isinstance(cluster.leader, Leader) and\
+                cluster.leader.name == self._name and isinstance(cluster.leader.version, int):
+            return self._client.kv.delete(self.leader_path, cas=cluster.leader.version)
+        return True
 
     @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)
+            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 +6,28 @@ 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, SyncState,\
+    TimelineHistory, ReturnFalseException, catch_return_false_exception, citus_group_re
 from ..exceptions import DCSError
 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 +40,21 @@ 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 +65,7 @@ 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 +76,14 @@ 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 +91,21 @@ 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',
+                                             '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 +113,7 @@ 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.
@@ -132,59 +140,53 @@ 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:
             try:
-                machines = list(self._get_members(base_uri, **kwargs))
+                machines = list(set(self._get_members(base_uri, **kwargs)))
                 logger.debug("Retrieved list of machines: %s", machines)
                 if machines:
                     random.shuffle(machines)
@@ -197,10 +199,30 @@ 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
@@ -216,12 +238,14 @@ class AbstractEtcdClientWithFailover(etcd.Client):
                 return response
             except (HTTPError, HTTPException, socket.error, socket.timeout) as e:
                 self.http.clear()
-                # switch to the next etcd node because we don't know exactly what happened,
-                # whether the key didn't received an update or there is a network problem.
-                if not retry and 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 not retry:
+                    if len(machines_cache) == 1:
+                        self.set_base_uri(self._base_uri)  # trigger Etcd3 watcher restart
+                    # switch to the next etcd node because we don't know exactly what happened,
+                    # 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 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)
@@ -233,10 +257,12 @@ 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
@@ -264,31 +290,34 @@ 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)
                 if nodes == 0:
                     self._update_machines_cache = True
+                    self.set_base_uri(self._base_uri)  # trigger Etcd3 watcher restart
                     raise ex
                 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'
@@ -313,15 +342,15 @@ 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']))]
 
@@ -337,13 +366,14 @@ 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
@@ -362,62 +392,73 @@ 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):
-        logger.info('Selected new etcd server %s', value)
-        self._base_uri = 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
 
 
 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 __del__(self) -> None:
+        try:
+            self.http.clear()
+        except (ReferenceError, TypeError, AttributeError):
+            pass
 
-    def _prepare_get_members(self, etcd_nodes):
+    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
@@ -426,25 +467,32 @@ class EtcdClient(AbstractEtcdClientWithFailover):
 
 class AbstractEtcd(AbstractDCS):
 
-    def __init__(self, config, client_cls, retry_errors_cls):
+    def __init__(self, config: Dict[str, Any], client_cls: Type[AbstractEtcdClientWithFailover],
+                 retry_errors_cls: Union[Type[Exception], Tuple[Type[Exception], ...]]) -> None:
         super(AbstractEtcd, self).__init__(config)
         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:
@@ -455,18 +503,43 @@ 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})
@@ -475,13 +548,14 @@ 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
@@ -500,8 +574,10 @@ 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('[]')
@@ -511,7 +587,7 @@ 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)
@@ -542,196 +618,228 @@ 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):
+    def __init__(self, config: Dict[str, Any]) -> None:
         super(Etcd, self).__init__(config, 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)
+        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 or '')
+        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]
+            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, last_lsn, members, failover, sync, history, slots, failsafe)
+
+    def _cluster_loader(self, path: str) -> Cluster:
+        result = self.retry(self._client.read, path, recursive=True)
+        nodes = {node.key[len(result.key):].lstrip('/'): node for node in result.leaves}
+        return self._cluster_from_nodes(result.etcd_index, nodes)
+
+    def _citus_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        clusters: Dict[int, Dict[str, etcd.EtcdResult]] = defaultdict(dict)
+        result = self.retry(self._client.read, path, recursive=True)
+        for node in result.leaves:
+            key = node.key[len(result.key):].lstrip('/').split('/', 1)
+            if len(key) == 2 and citus_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)
+            cluster = loader(path)
         except etcd.EtcdKeyNotFound:
-            cluster = Cluster(None, None, None, None, [], None, None, None, None)
+            cluster = Cluster.empty()
         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) -> 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 +3,12 @@ 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 ..request import get as requests_get
+from ..utils import uri
 
 logger = logging.getLogger(__name__)
 
@@ -14,29 +17,31 @@ 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 +49,7 @@ 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 +60,20 @@ 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]) -> 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})
 
-    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 +4,35 @@ 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, SyncState, TimelineHistory, citus_group_re
+from ..exceptions import DCSError
 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 +40,7 @@ class _TCPTransport(TCPTransport):
             return False
 
 
-def resolve_host(self):
+def resolve_host(self: TCPNode) -> Optional[str]:
     return globalDnsResolver().resolve(self.host)
 
 
@@ -39,17 +49,19 @@ setattr(TCPNode, 'ip', property(resolve_host))
 
 class SyncObjUtility(object):
 
-    def __init__(self, otherNodes, conf):
+    def __init__(self, otherNodes: Collection[Union[str, TCPNode]], conf: SyncObjConf, retry_timeout: int = 10) -> None:
         self._nodes = otherNodes
-        self._utility = TcpUtility(conf.password)
+        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:
@@ -58,11 +70,12 @@ class SyncObjUtility(object):
 
 class DynMemberSyncObj(SyncObj):
 
-    def __init__(self, selfAddress, partnerAddrs, conf):
+    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
 
-        utility = SyncObjUtility(partnerAddrs, conf)
+        utility = SyncObjUtility(partnerAddrs, conf, retry_timeout)
         members = utility.getMembers()
         add_self = members and selfAddress not in members
 
@@ -75,12 +88,12 @@ 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 +105,16 @@ 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.__retry_timeout = None
+        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)
@@ -121,23 +135,23 @@ class KVStoreTTL(DynMemberSyncObj):
                            journalFile=(file_template + '.journal' if self_addr else None),
                            onReady=on_ready, dynamicMembershipChange=True)
 
-        super(KVStoreTTL, self).__init__(self_addr, partner_addrs, conf)
-        self.__data = {}
+        super(KVStoreTTL, self).__init__(self_addr, partner_addrs, conf, self.__retry_timeout)
+        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 +170,12 @@ 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 +187,32 @@ 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 +223,41 @@ 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 +265,17 @@ 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()
@@ -261,7 +284,7 @@ class KVStoreTTL(DynMemberSyncObj):
 
 class Raft(AbstractDCS):
 
-    def __init__(self, config):
+    def __init__(self, config: Dict[str, Any]) -> None:
         super(Raft, self).__init__(config)
         self._ttl = int(config.get('ttl') or 30)
 
@@ -271,13 +294,12 @@ class Raft(AbstractDCS):
 
         while True:
             ready_event.wait(5)
-            if ready_event.isSet() or self._sync_obj.applied_local_log:
+            if ready_event.is_set() or self._sync_obj.applied_local_log:
                 break
             else:
                 logger.info('waiting on raft')
-        self.set_retry_timeout(int(config.get('retry_timeout') or 10))
 
-    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 \
@@ -285,35 +307,29 @@ 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']
@@ -341,7 +357,7 @@ class Raft(AbstractDCS):
             slots = None
 
         try:
-            last_lsn = int(last_lsn)
+            last_lsn = int(last_lsn or '')
         except Exception:
             last_lsn = 0
 
@@ -364,60 +380,95 @@ 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, last_lsn, members, failover, sync, history, slots, failsafe)
 
-    def _write_status(self, value):
-        return self._sync_obj.set(self.status_path, value, timeout=1)
+    def _cluster_loader(self, path: str) -> Cluster:
+        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 _update_leader(self):
-        ret = self._sync_obj.set(self.leader_path, self._name, ttl=self._ttl, prevValue=self._name)
+    def _citus_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        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 citus_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) -> 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

@@ -1,16 +1,22 @@
 import json
 import logging
 import select
+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.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, SyncState, TimelineHistory, citus_group_re
 from ..exceptions import DCSError
 from ..utils import deep_compare
+if TYPE_CHECKING:  # pragma: no cover
+    from ..config import Config
 
 logger = logging.getLogger(__name__)
 
@@ -21,14 +27,14 @@ 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".
@@ -39,26 +45,34 @@ 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: Any, **kwargs: Any) -> Any:
+        """
+        Python 3.XY may raise following exceptions if select/poll are called with an invalid socket:
+        - `ValueError`: because fd == -1
+        - `TypeError`: Invalid file descriptor: -1 (starting from kazoo 2.9)
+        Python 2.7 may raise the `IOError` instead of `socket.error` (starting from kazoo 2.9)
+
+        When it is appropriate we map these exceptions to `socket.error`.
+        """
 
-    def select(self, *args, **kwargs):
-        """Python3 raises `ValueError` if socket is closed, because fd == -1"""
         try:
             return super(PatroniSequentialThreadingHandler, self).select(*args, **kwargs)
-        except ValueError as e:
+        except (TypeError, ValueError) as 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.
@@ -72,7 +86,7 @@ class PatroniKazooClient(KazooClient):
 
 class ZooKeeper(AbstractDCS):
 
-    def __init__(self, config):
+    def __init__(self, config: Dict[str, Any]) -> None:
         super(ZooKeeper, self).__init__(config)
 
         hosts = config.get('hosts', [])
@@ -83,21 +97,36 @@ class ZooKeeper(AbstractDCS):
                    'cert': 'certfile', 'key': 'keyfile', 'key_password': 'keyfile_password'}
         kwargs = {v: config[k] for k, v in mapping.items() if k in config}
 
+        if 'set_acls' in config:
+            default_acl: List[ACL] = []
+            for principal, permissions in config['set_acls'].items():
+                normalizedPermissions = [p.upper() for p in permissions]
+                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)
 
-        self._fetch_cluster = True
-        self._fetch_status = True
+        self._fetch_cluster: bool = True
+        self._fetch_status: bool = True
+        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
@@ -110,28 +139,30 @@ 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):
+    def session_listener(self, state: str) -> None:
         if state in [KazooState.SUSPENDED, KazooState.LOST]:
             self.cluster_watcher(None)
 
-    def status_watcher(self, event):
+    def status_watcher(self, event: Optional[WatchedEvent]) -> None:
         self._fetch_status = True
         self.event.set()
 
-    def cluster_watcher(self, event):
+    def cluster_watcher(self, event: Optional[WatchedEvent]) -> None:
         self._fetch_cluster = True
-        self.status_watcher(event)
+        if not event or event.state != KazooState.CONNECTED or event.path.startswith(self.client_path('')):
+            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
@@ -142,7 +173,7 @@ 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)."""
@@ -153,24 +184,26 @@ 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):
+    def get_status(self, path: str, leader: Optional[Leader]) -> Tuple[int, Optional[Dict[str, int]]]:
         watch = self.status_watcher if not leader or leader.name != self._name else None
 
-        status = self.get_node(self.status_path, watch)
+        status = self.get_node(path + self._STATUS, watch)
         if status:
             try:
                 status = json.loads(status[0])
@@ -179,12 +212,12 @@ class ZooKeeper(AbstractDCS):
             except Exception:
                 slots = last_lsn = None
         else:
-            last_lsn = self.get_node(self.leader_optime_path, watch)
+            last_lsn = self.get_node(path + self._LEADER_OPTIME, watch)
             last_lsn = last_lsn and last_lsn[0]
             slots = None
 
         try:
-            last_lsn = int(last_lsn)
+            last_lsn = int(last_lsn or '')
         except Exception:
             last_lsn = 0
 
@@ -192,99 +225,115 @@ class ZooKeeper(AbstractDCS):
         return last_lsn, slots
 
     @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, watch: Optional[Callable[[WatchedEvent], None]] = None) -> List[str]:
         try:
             return self._client.get_children(key, watch)
         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, self.cluster_watcher):
+            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):
+    def _cluster_loader(self, path: str) -> Cluster:
         self._fetch_cluster = False
         self.event.clear()
-        nodes = set(self.get_children(self.client_path(''), self.cluster_watcher))
+        nodes = set(self.get_children(path, self.cluster_watcher))
         if not nodes:
             self._fetch_cluster = True
 
         # 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.cluster_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, watch=self.cluster_watcher) 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, watch=self.cluster_watcher) 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) 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)
+            self._fetch_cluster = member.version == -1
 
         # get last known leader lsn and slots
-        last_lsn, slots = self.get_status(leader)
+        last_lsn, slots = 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, watch=self.cluster_watcher) 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, watch=self.cluster_watcher) 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
+        return Cluster(initialize, config, leader, last_lsn, members, failover, sync, history, slots, failsafe)
+
+    def _citus_cluster_loader(self, path: str) -> Dict[int, Cluster]:
+        fetch_cluster = False
+        ret: Dict[int, Cluster] = {}
+        for node in self.get_children(path, self.cluster_watcher):
+            if citus_group_re.match(node):
+                ret[int(node)] = self._cluster_loader(path + node + '/')
+                fetch_cluster = fetch_cluster or self._fetch_cluster
+        self._fetch_cluster = fetch_cluster
+        return ret
+
+    def _load_cluster(
+            self, path: str, loader: Callable[[str], Union[Cluster, Dict[int, Cluster]]]
+    ) -> Union[Cluster, Dict[int, Cluster]]:
+        cluster = self.cluster if path == self._base_path + '/' else None
         if self._fetch_cluster or cluster is None:
             try:
-                cluster = self._client.retry(self._inner_load_cluster)
+                cluster = self._client.retry(loader, path)
             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 and we are not leader
-        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) and\
-                not (cluster.leader and cluster.leader.name == self._name):
-            try:
-                last_lsn, slots = self.get_status(cluster.leader)
+        # 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()
-                cluster = Cluster(cluster.initialize, cluster.config, cluster.leader, last_lsn,
-                                  cluster.members, cluster.failover, cluster.sync, cluster.history, slots)
-            except Exception:
-                pass
+            else:
+                try:
+                    last_lsn, slots = self.get_status(self.client_path(''), cluster.leader)
+                    self.event.clear()
+                    new_cluster: List[Any] = list(cluster)
+                    new_cluster[3] = last_lsn
+                    new_cluster[8] = slots
+                    cluster = Cluster(*new_cluster)
+                except Exception:
+                    pass
         return cluster
 
-    def _bypass_caches(self):
+    def _bypass_caches(self) -> None:
         self._fetch_cluster = True
 
-    def _create(self, path, value, retry=False, ephemeral=False):
+    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)
@@ -295,50 +344,63 @@ 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)
-        encoded_data = json.dumps(data, separators=(',', ':')).encode('utf-8')
-        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'))):
+        member_data = self.__last_member_data or member and member.data
+        #  We want to notify leader if some important fields in the member key changed by removing ZNode
+        if member and (self._client.client_id is not None and member.session != self._client.client_id[0]
+                       or not (member_data and deep_compare(member_data.get('tags', {}), data.get('tags', {}))
+                               and (member_data.get('state') == data.get('state')
+                                    or 'running' not in (member_data.get('state'), data.get('state')))
+                               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:
@@ -347,13 +409,14 @@ class ZooKeeper(AbstractDCS):
                 return False
             member = None
 
-        if member:
-            if deep_compare(data, member.data):
+        encoded_data = json.dumps(data, separators=(',', ':')).encode('utf-8')
+        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:
                 if not isinstance(e, NodeExistsError):
@@ -361,56 +424,82 @@ class ZooKeeper(AbstractDCS):
                     return False
         try:
             self._client.set_async(self.member_path, encoded_data).get(timeout=1)
+            self.__last_member_data = data
             return True
         except Exception:
             logger.exception('touch_member')
 
         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) -> 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)
+    def watch(self, leader_version: Optional[int], timeout: float) -> bool:
+        ret = super(ZooKeeper, self).watch(leader_version, timeout + 0.5)
         if ret and not self._fetch_status:
             self._fetch_cluster = True
         return ret or self._fetch_cluster

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/log.py

@@ -1,3 +1,8 @@
+"""Patroni logging facilities.
+
+Daemon processes will use a 2-step logging handler. Whenever a log message is issued it is initially enqueued in-memory
+and is later asynchronously flushed by a thread to the final destination.
+"""
 import logging
 import os
 import sys
@@ -5,41 +10,84 @@ import sys
 from copy import deepcopy
 from logging.handlers import RotatingFileHandler
 from patroni.utils import deep_compare
-from six.moves.queue import Queue, Full
+from queue import Queue, Full
 from threading import Lock, Thread
 
+from typing import Any, Dict, List, Optional, Union, TYPE_CHECKING
+
 _LOGGER = logging.getLogger(__name__)
 
 
-def debug_exception(logger_obj, msg, *args, **kwargs):
+def debug_exception(self: logging.Logger, msg: object, *args: Any, **kwargs: Any) -> None:
+    """Add full stack trace info to debug log messages and partial to others.
+
+    Handle :func:`exception` calls for *self*.
+
+    .. note::
+        * If *self* log level is set to ``DEBUG``, then issue a ``DEBUG`` message with the complete stack trace;
+        * If *self* log level is ``INFO`` or higher, then issue an ``ERROR`` message with only the last line of
+            the stack trace.
+
+    :param self: logger for which :func:`exception` will be processed.
+    :param msg: the message related to the exception to be logged.
+    :param args: positional arguments to be passed to :func:`self.debug` or :func:`loger_obj.error`.
+    :param kwargs: keyword arguments to be passed to :func:`self.debug` or :func:`loger_obj.error`.
+    """
     kwargs.pop("exc_info", False)
-    if logger_obj.isEnabledFor(logging.DEBUG):
-        logger_obj.debug(msg, *args, exc_info=True, **kwargs)
+    if self.isEnabledFor(logging.DEBUG):
+        self.debug(msg, *args, exc_info=True, **kwargs)
     else:
         msg = "{0}, DETAIL: '{1}'".format(msg, sys.exc_info()[1])
-        logger_obj.error(msg, *args, exc_info=False, **kwargs)
+        self.error(msg, *args, exc_info=False, **kwargs)
 
 
-def error_exception(logger_obj, msg, *args, **kwargs):
+def error_exception(self: logging.Logger, msg: object, *args: Any, **kwargs: Any) -> None:
+    """Add full stack trace info to error messages.
+
+    Handle :func:`exception` calls for *self*.
+
+    .. note::
+        * By default issue an ``ERROR`` message with the complete stack trace. If you do not want to show the complete
+        stack trace, call with ``exc_info=False``.
+
+    :param self: logger for which :func:`exception` will be processed.
+    :param msg: the message related to the exception to be logged.
+    :param args: positional arguments to be passed to :func:`loger_obj.error`.
+    :param kwargs: keyword arguments to be passed to :func:`loger_obj.error`.
+    """
     exc_info = kwargs.pop("exc_info", True)
-    logger_obj.error(msg, *args, exc_info=exc_info, **kwargs)
+    self.error(msg, *args, exc_info=exc_info, **kwargs)
 
 
 class QueueHandler(logging.Handler):
+    """Queue-based logging handler.
 
-    def __init__(self):
-        logging.Handler.__init__(self)
-        self.queue = Queue()
+    :ivar queue: queue to hold log messages that are pending to be flushed to the final destination.
+    """
+
+    def __init__(self) -> None:
+        """Queue initialised and initial records_lost established."""
+        super().__init__()
+        self.queue: Queue[Union[logging.LogRecord, None]] = Queue()
         self._records_lost = 0
 
-    def _put_record(self, record):
+    def _put_record(self, record: logging.LogRecord) -> None:
+        """Asynchronously enqueue a log record.
+
+        :param record: the record to be logged.
+        """
         self.format(record)
         record.msg = record.message
         record.args = None
         record.exc_info = None
         self.queue.put_nowait(record)
 
-    def _try_to_report_lost_records(self):
+    def _try_to_report_lost_records(self) -> None:
+        """Report the number of log messages that have been lost and reset the counter.
+
+        .. note::
+            It will issue an ``WARNING`` message in the logs with the number of lost log messages.
+        """
         if self._records_lost:
             try:
                 record = _LOGGER.makeRecord(_LOGGER.name, logging.WARNING, __file__, 0,
@@ -50,7 +98,15 @@ class QueueHandler(logging.Handler):
             except Exception:
                 pass
 
-    def emit(self, record):
+    def emit(self, record: logging.LogRecord) -> None:
+        """Handle each log record that is emitted.
+
+        Call :func:`_put_record` to enqueue the emitted log record.
+
+        Also check if we have previously lost any log record, and if so, log a ``WARNING`` message.
+
+        :param record: the record that was emitted.
+        """
         try:
             self._put_record(record)
             self._try_to_report_lost_records()
@@ -58,21 +114,60 @@ class QueueHandler(logging.Handler):
             self._records_lost += 1
 
     @property
-    def records_lost(self):
+    def records_lost(self) -> int:
+        """Number of log messages that have been lost while the queue was full."""
         return self._records_lost
 
 
 class ProxyHandler(logging.Handler):
+    """Handle log records in place of pending log handlers.
 
-    def __init__(self, patroni_logger):
-        logging.Handler.__init__(self)
+    .. note::
+        This is used to handle log messages while the logger thread has not started yet, in which case the queue-based
+        handler is not yet started.
+
+    :ivar patroni_logger: the logger thread.
+    """
+
+    def __init__(self, patroni_logger: 'PatroniLogger') -> None:
+        """Create a new :class:`ProxyHandler` instance.
+
+        :param patroni_logger: the logger thread.
+        """
+        super().__init__()
         self.patroni_logger = patroni_logger
 
-    def emit(self, record):
-        self.patroni_logger.log_handler.handle(record)
+    def emit(self, record: logging.LogRecord) -> None:
+        """Emit each log record that is handled.
+
+        Will push the log record down to :func:`handle` method of the currently configured log handler.
+
+        :param record: the record that was emitted.
+        """
+        if self.patroni_logger.log_handler is not None:
+            self.patroni_logger.log_handler.handle(record)
 
 
 class PatroniLogger(Thread):
+    """Logging thread for the Patroni daemon process.
+
+    It is a 2-step logging approach. Any time a log message is issued it is initially enqueued in-memory, and then
+    asynchronously flushed to the final destination by the logging thread.
+
+    .. seealso::
+        :class:`QueueHandler`: object used for enqueueing messages in-memory.
+
+    :cvar DEFAULT_LEVEL: default logging level (``INFO``).
+    :cvar DEFAULT_TRACEBACK_LEVEL: default traceback logging level (``ERROR``).
+    :cvar DEFAULT_FORMAT: default format of log messages (``%(asctime)s %(levelname)s: %(message)s``).
+    :cvar NORMAL_LOG_QUEUE_SIZE: expected number of log messages per HA loop when operating under a normal situation.
+    :cvar DEFAULT_MAX_QUEUE_SIZE: default maximum queue size for holding a backlog of log messages that are pending
+        to be flushed.
+    :cvar LOGGING_BROKEN_EXIT_CODE: exit code to be used if it detects(``5``).
+
+    :ivar log_handler: log handler that is currently being used by the thread.
+    :ivar log_handler_lock: lock used to modify ``log_handler``.
+    """
 
     DEFAULT_LEVEL = 'INFO'
     DEFAULT_TRACEBACK_LEVEL = 'ERROR'
@@ -82,14 +177,24 @@ class PatroniLogger(Thread):
     DEFAULT_MAX_QUEUE_SIZE = 1000
     LOGGING_BROKEN_EXIT_CODE = 5
 
-    def __init__(self):
+    def __init__(self) -> None:
+        """Prepare logging queue and proxy handlers as they become ready during daemon startup.
+
+        .. note::
+            While Patroni is starting up it keeps ``DEBUG`` log level, and writes log messages through a proxy handler.
+            Once the logger thread is finally started, it switches from that proxy handler to the queue based logger,
+            and applies the configured log settings. The switching is used to avoid that the logger thread prevents
+            Patroni from shutting down if any issue occurs in the meantime until the thread is properly started.
+        """
         super(PatroniLogger, self).__init__()
         self._queue_handler = QueueHandler()
         self._root_logger = logging.getLogger()
-        self._config = None
+        self._config: Optional[Dict[str, Any]] = None
         self.log_handler = None
         self.log_handler_lock = Lock()
-        self._old_handlers = []
+        self._old_handlers: List[logging.Handler] = []
+        # initially set log level to ``DEBUG`` while the logger thread has not started running yet. The daemon process
+        # will later adjust all log related settings with what was provided through the user configuration file.
         self.reload_config({'level': 'DEBUG'})
         # We will switch to the QueueHandler only when thread was started.
         # This is necessary to protect from the cases when Patroni constructor
@@ -97,26 +202,46 @@ class PatroniLogger(Thread):
         self._proxy_handler = ProxyHandler(self)
         self._root_logger.addHandler(self._proxy_handler)
 
-    def update_loggers(self):
-        loggers = deepcopy(self._config.get('loggers') or {})
+    def update_loggers(self) -> None:
+        """Configure loggers' log level as defined in ``log.loggers` section of Patroni configuration.
+
+        .. note::
+            It creates logger objects that are not defined yet in the log manager.
+        """
+        loggers = deepcopy((self._config or {}).get('loggers') or {})
         for name, logger in self._root_logger.manager.loggerDict.items():
+            # ``Placeholder`` is a node in the log manager for which no logger has been defined. We are interested only
+            # in the ones that were defined
             if not isinstance(logger, logging.PlaceHolder):
+                # if this logger is present in ``log.loggers`` Patroni configuration, use the configured level,
+                # otherwise use ``logging.NOTSET``, which means it will inherit the level from any parent node up to
+                # the root for which log level is defined.
                 level = loggers.pop(name, logging.NOTSET)
                 logger.setLevel(level)
 
+        # define loggers that do not exist yet and set level as configured in ``log.loggers`` section of configuration.
         for name, level in loggers.items():
             logger = self._root_logger.manager.getLogger(name)
             logger.setLevel(level)
 
-    def reload_config(self, config):
+    def reload_config(self, config: Dict[str, Any]) -> None:
+        """Apply log related configuration.
+
+        .. note::
+            It is also able to deal with runtime configuration changes.
+
+        :param config: ``log`` section from Patroni configuration.
+        """
         if self._config is None or not deep_compare(self._config, config):
             with self._queue_handler.queue.mutex:
                 self._queue_handler.queue.maxsize = config.get('max_queue_size', self.DEFAULT_MAX_QUEUE_SIZE)
 
             self._root_logger.setLevel(config.get('level', PatroniLogger.DEFAULT_LEVEL))
             if config.get('traceback_level', PatroniLogger.DEFAULT_TRACEBACK_LEVEL).lower() == 'debug':
+                # show stack traces only if ``log.traceback_level`` is ``DEBUG``
                 logging.Logger.exception = debug_exception
             else:
+                # show stack traces as ``ERROR`` log messages
                 logging.Logger.exception = error_exception
 
             new_handler = None
@@ -124,7 +249,9 @@ class PatroniLogger(Thread):
                 if not isinstance(self.log_handler, RotatingFileHandler):
                     new_handler = RotatingFileHandler(os.path.join(config['dir'], __name__))
                 handler = new_handler or self.log_handler
-                handler.maxBytes = int(config.get('file_size', 25000000))
+                if TYPE_CHECKING:  # pragma: no cover
+                    assert isinstance(handler, RotatingFileHandler)
+                handler.maxBytes = int(config.get('file_size', 25000000))  # pyright: ignore [reportGeneralTypeIssues]
                 handler.backupCount = int(config.get('file_num', 4))
             else:
                 if self.log_handler is None or isinstance(self.log_handler, RotatingFileHandler):
@@ -137,7 +264,7 @@ class PatroniLogger(Thread):
             olddateformat = (self._config or {}).get('dateformat') or None
             dateformat = config.get('dateformat') or None  # Convert empty string to `None`
 
-            if oldlogformat != logformat or olddateformat != dateformat or new_handler:
+            if (oldlogformat != logformat or olddateformat != dateformat or new_handler) and handler:
                 handler.setFormatter(logging.Formatter(logformat, dateformat))
 
             if new_handler:
@@ -149,7 +276,13 @@ class PatroniLogger(Thread):
             self._config = config.copy()
             self.update_loggers()
 
-    def _close_old_handlers(self):
+    def _close_old_handlers(self) -> None:
+        """Close old log handlers.
+
+        .. note::
+            It is used to remove different handlers that were configured previous to a reload in the configuration,
+            e.g. if we are switching from :class:`RotatingFileHandler` to class:`StreamHandler` and vice-versa.
+        """
         while True:
             with self.log_handler_lock:
                 if not self._old_handlers:
@@ -160,7 +293,11 @@ class PatroniLogger(Thread):
             except Exception:
                 _LOGGER.exception('Failed to close the old log handler %s', handler)
 
-    def run(self):
+    def run(self) -> None:
+        """Run logger's thread main loop.
+
+        Keep consuming log queue until requested to quit through ``None`` special log record.
+        """
         # switch to QueueHandler only when the thread was started
         with self.log_handler_lock:
             self._root_logger.addHandler(self._queue_handler)
@@ -170,12 +307,17 @@ class PatroniLogger(Thread):
 
         while True:
             self._close_old_handlers()
+            if TYPE_CHECKING:  # pragma: no cover
+                assert self.log_handler is not None
 
             record = self._queue_handler.queue.get(True)
+            # special message that indicates Patroni is shutting down
             if record is None:
                 break
 
             if self._root_logger.level == logging.INFO:
+                # messages like ``Lock owner: postgresql0; I am postgresql1`` will be shown only when stream doesn't
+                # look normal. This is used to reduce chattiness of Patroni logs.
                 if record.msg.startswith('Lock owner: '):
                     prev_record, record = record, None
                 else:
@@ -189,8 +331,10 @@ class PatroniLogger(Thread):
 
             self._queue_handler.queue.task_done()
 
-    def shutdown(self):
+    def shutdown(self) -> None:
+        """Shut down the logger thread."""
         try:
+            # ``None`` is a special message indicating to queue handler that it should quit its main loop.
             self._queue_handler.queue.put_nowait(None)
         except Full:  # Queue is full.
             # It seems that logging is not working, exiting with non-standard exit-code is the best we can do.
@@ -199,9 +343,11 @@ class PatroniLogger(Thread):
         logging.shutdown()
 
     @property
-    def queue_size(self):
+    def queue_size(self) -> int:
+        """Number of log records in the queue."""
         return self._queue_handler.queue.qsize()
 
     @property
-    def records_lost(self):
+    def records_lost(self) -> int:
+        """Number of logging records that have been lost while the queue was full."""
         return self._queue_handler.records_lost

patroni/postgresql/bootstrap.py

@@ -4,51 +4,106 @@ import shlex
 import tempfile
 import time
 
-from patroni.dcs import RemoteMember
-from patroni.utils import deep_compare
-from six import string_types
+from typing import Any, Callable, Dict, List, Optional, Union, Tuple, TYPE_CHECKING
+
+from ..async_executor import CriticalTask
+from ..dcs import Leader, Member, RemoteMember
+from ..psycopg import quote_ident, quote_literal
+from ..utils import deep_compare, unquote
+
+if TYPE_CHECKING:  # pragma: no cover
+    from . import Postgresql
 
 logger = logging.getLogger(__name__)
 
 
 class Bootstrap(object):
 
-    def __init__(self, postgresql):
+    def __init__(self, postgresql: 'Postgresql') -> None:
         self._postgresql = postgresql
         self._running_custom_bootstrap = False
 
     @property
-    def running_custom_bootstrap(self):
+    def running_custom_bootstrap(self) -> bool:
         return self._running_custom_bootstrap
 
     @property
-    def keep_existing_recovery_conf(self):
+    def keep_existing_recovery_conf(self) -> bool:
         return self._running_custom_bootstrap and self._keep_existing_recovery_conf
 
     @staticmethod
-    def process_user_options(tool, options, not_allowed_options, error_handler):
-        user_options = []
+    def process_user_options(tool: str,
+                             options: Union[Any, Dict[str, str], List[Union[str, Dict[str, Any]]]],
+                             not_allowed_options: Tuple[str, ...],
+                             error_handler: Callable[[str], None]) -> List[str]:
+        """Format *options* in a list or dictionary format into command line long form arguments.
 
-        def option_is_allowed(name):
+        .. note::
+            The format of the output of this method is to prepare arguments for use in the ``initdb``
+            method of `self._postgres`.
+
+        :Example:
+
+            The *options* can be defined as a dictionary of key, values to be converted into arguments:
+            >>> Bootstrap.process_user_options('foo', {'foo': 'bar'}, (), print)
+            ['--foo=bar']
+
+            Or as a list of single string arguments
+            >>> Bootstrap.process_user_options('foo', ['yes'], (), print)
+            ['--yes']
+
+            Or as a list of key, value options
+            >>> Bootstrap.process_user_options('foo', [{'foo': 'bar'}], (), print)
+            ['--foo=bar']
+
+            Or a combination of single and key, values
+            >>> Bootstrap.process_user_options('foo', ['yes', {'foo': 'bar'}], (), print)
+            ['--yes', '--foo=bar']
+
+            Options that contain spaces are passed as is to ``subprocess.call``
+            >>> Bootstrap.process_user_options('foo', [{'foo': 'bar baz'}], (), print)
+            ['--foo=bar baz']
+
+            Options that are quoted will be unquoted, so the quotes aren't interpreted
+            literally by the postgres command
+            >>> Bootstrap.process_user_options('foo', [{'foo': '"bar baz"'}], (), print)
+            ['--foo=bar baz']
+
+        .. note::
+            The *error_handler* is called when any of these conditions are met:
+
+            * Key, value dictionaries in the list form contains multiple keys.
+            * If a key is listed in *not_allowed_options*.
+            * If the options list is not in the required structure.
+
+        :param tool: The name of the tool used in error reports to *error_handler*
+        :param options: Options to parse as a list of key, values or single values, or a dictionary
+        :param not_allowed_options: List of keys that cannot be used in the list of key, value formatted options
+        :param error_handler: A function which will be called when an error condition is encountered
+        :returns: List of long form arguments to pass to the named tool
+        """
+        user_options: List[str] = []
+
+        def option_is_allowed(name: str) -> bool:
             ret = name not in not_allowed_options
             if not ret:
                 error_handler('{0} option for {1} is not allowed'.format(name, tool))
             return ret
 
         if isinstance(options, dict):
-            for k, v in options.items():
-                if k and v:
-                    user_options.append('--{0}={1}'.format(k, v))
+            for key, val in options.items():
+                if key and val:
+                    user_options.append('--{0}={1}'.format(key, unquote(val)))
         elif isinstance(options, list):
             for opt in options:
-                if isinstance(opt, string_types) and option_is_allowed(opt):
+                if isinstance(opt, str) and option_is_allowed(opt):
                     user_options.append('--{0}'.format(opt))
                 elif isinstance(opt, dict):
                     keys = list(opt.keys())
-                    if len(keys) != 1 or not isinstance(opt[keys[0]], string_types) or not option_is_allowed(keys[0]):
+                    if len(keys) != 1 or not isinstance(opt[keys[0]], str) or not option_is_allowed(keys[0]):
                         error_handler('Error when parsing {0} key-value option {1}: only one key-value is allowed'
                                       ' and value should be a string'.format(tool, opt[keys[0]]))
-                    user_options.append('--{0}={1}'.format(keys[0], opt[keys[0]]))
+                    user_options.append('--{0}={1}'.format(keys[0], unquote(opt[keys[0]])))
                 else:
                     error_handler('Error when parsing {0} option {1}: value should be string value'
                                   ' or a single key-value pair'.format(tool, opt))
@@ -56,11 +111,11 @@ class Bootstrap(object):
             error_handler('{0} options must be list or dict'.format(tool))
         return user_options
 
-    def _initdb(self, config):
-        self._postgresql.set_state('initalizing new cluster')
+    def _initdb(self, config: Any) -> bool:
+        self._postgresql.set_state('initializing new cluster')
         not_allowed_options = ('pgdata', 'nosync', 'pwfile', 'sync-only', 'version')
 
-        def error_handler(e):
+        def error_handler(e: str) -> None:
             raise Exception(e)
 
         options = self.process_user_options('initdb', config or [], not_allowed_options, error_handler)
@@ -74,9 +129,8 @@ class Bootstrap(object):
                 os.write(fd, self._postgresql.config.superuser['password'].encode('utf-8'))
                 os.close(fd)
                 options.append('--pwfile={0}'.format(pwfile))
-        options = ['-o', ' '.join(options)] if options else []
 
-        ret = self._postgresql.pg_ctl('initdb', *options)
+        ret = self._postgresql.initdb(*options)
         if pwfile:
             os.remove(pwfile)
         if ret:
@@ -85,7 +139,7 @@ class Bootstrap(object):
             self._postgresql.set_state('initdb failed')
         return ret
 
-    def _post_restore(self):
+    def _post_restore(self) -> None:
         self._postgresql.config.restore_configuration_files()
         self._postgresql.configure_server_parameters()
 
@@ -96,7 +150,7 @@ class Bootstrap(object):
         if os.path.exists(trigger_file):
             os.unlink(trigger_file)
 
-    def _custom_bootstrap(self, config):
+    def _custom_bootstrap(self, config: Any) -> bool:
         self._postgresql.set_state('running custom bootstrap script')
         params = [] if config.get('no_params') else ['--scope=' + self._postgresql.scope,
                                                      '--datadir=' + self._postgresql.data_dir]
@@ -116,7 +170,7 @@ class Bootstrap(object):
             self._postgresql.config.remove_recovery_conf()
         return True
 
-    def call_post_bootstrap(self, config):
+    def call_post_bootstrap(self, config: Dict[str, Any]) -> bool:
         """
         runs a script after initdb or custom bootstrap script is called and waits until completion.
         """
@@ -143,7 +197,7 @@ class Bootstrap(object):
                 return False
         return True
 
-    def create_replica(self, clone_member):
+    def create_replica(self, clone_member: Union[Leader, Member, None]) -> Optional[int]:
         """
             create the replica according to the replica_method
             defined by the user.  this is a list, so we need to
@@ -153,12 +207,12 @@ class Bootstrap(object):
         self._postgresql.set_state('creating replica')
         self._postgresql.schedule_sanity_checks_after_pause()
 
-        is_remote_master = isinstance(clone_member, RemoteMember)
+        is_remote_member = isinstance(clone_member, RemoteMember)
 
         # get list of replica methods either from clone member or from
         # the config. If there is no configuration key, or no value is
         # specified, use basebackup
-        replica_methods = (clone_member.create_replica_methods if is_remote_master
+        replica_methods = (clone_member.create_replica_methods if is_remote_member
                            else self._postgresql.create_replica_methods) or ['basebackup']
 
         if clone_member and clone_member.conn_url:
@@ -210,7 +264,7 @@ class Bootstrap(object):
                                           "datadir": self._postgresql.data_dir,
                                           "connstring": connstring})
                 else:
-                    for param in ('no_params', 'no_master', 'keep_data'):
+                    for param in ('no_params', 'no_master', 'no_leader', 'keep_data'):
                         method_config.pop(param, None)
                 params = ["--{0}={1}".format(arg, val) for arg, val in method_config.items()]
                 try:
@@ -230,7 +284,7 @@ class Bootstrap(object):
         self._postgresql.set_state('stopped')
         return ret
 
-    def basebackup(self, conn_url, env, options):
+    def basebackup(self, conn_url: str, env: Dict[str, str], options: Dict[str, Any]) -> Optional[int]:
         # creates a replica data dir using pg_basebackup.
         # this is the default, built-in create_replica_methods
         # tries twice, then returns failure (as 1)
@@ -265,9 +319,9 @@ class Bootstrap(object):
 
         return ret
 
-    def clone(self, clone_member):
+    def clone(self, clone_member: Union[Leader, Member, None]) -> bool:
         """
-             - initialize the replica from an existing member (master or replica)
+             - initialize the replica from an existing member (primary or replica)
              - initialize the replica using the replica creation method that
                works without the replication connection (i.e. restore from on-disk
                base backup)
@@ -278,7 +332,7 @@ class Bootstrap(object):
             self._post_restore()
         return ret
 
-    def bootstrap(self, config):
+    def bootstrap(self, config: Dict[str, Any]) -> bool:
         """ Initialize a new node from scratch and start it. """
         pg_hba = config.get('pg_hba', [])
         method = config.get('method') or 'initdb'
@@ -290,39 +344,39 @@ class Bootstrap(object):
             method = 'initdb'
             do_initialize = self._initdb
         return do_initialize(config.get(method)) and self._postgresql.config.append_pg_hba(pg_hba) \
-            and self._postgresql.config.save_configuration_files() and self._postgresql.start()
+            and self._postgresql.config.save_configuration_files() and bool(self._postgresql.start())
 
-    def create_or_update_role(self, name, password, options):
+    def create_or_update_role(self, name: str, password: Optional[str], options: List[str]) -> None:
         options = list(map(str.upper, options))
         if 'NOLOGIN' not in options and 'LOGIN' not in options:
             options.append('LOGIN')
 
-        params = [name]
         if password:
-            options.extend(['PASSWORD', '%s'])
-            params.extend([password, password])
+            options.extend(['PASSWORD', quote_literal(password)])
 
         sql = """DO $$
 BEGIN
     SET local synchronous_commit = 'local';
-    PERFORM * FROM pg_authid WHERE rolname = %s;
+    PERFORM * FROM pg_catalog.pg_authid WHERE rolname = {0};
     IF FOUND THEN
-        ALTER ROLE "{0}" WITH {1};
+        ALTER ROLE {1} WITH {2};
     ELSE
-        CREATE ROLE "{0}" WITH {1};
+        CREATE ROLE {1} WITH {2};
     END IF;
-END;$$""".format(name, ' '.join(options))
+END;$$""".format(quote_literal(name), quote_ident(name, self._postgresql.connection()), ' '.join(options))
         self._postgresql.query('SET log_statement TO none')
         self._postgresql.query('SET log_min_duration_statement TO -1')
         self._postgresql.query("SET log_min_error_statement TO 'log'")
+        self._postgresql.query("SET pg_stat_statements.track_utility to 'off'")
         try:
-            self._postgresql.query(sql, *params)
+            self._postgresql.query(sql)
         finally:
             self._postgresql.query('RESET log_min_error_statement')
             self._postgresql.query('RESET log_min_duration_statement')
             self._postgresql.query('RESET log_statement')
+            self._postgresql.query('RESET pg_stat_statements.track_utility')
 
-    def post_bootstrap(self, config, task):
+    def post_bootstrap(self, config: Dict[str, Any], task: CriticalTask) -> Optional[bool]:
         try:
             postgresql = self._postgresql
             superuser = postgresql.config.superuser
@@ -342,8 +396,8 @@ END;$$""".format(name, ' '.join(options))
                         sql = """DO $$
 BEGIN
     SET local synchronous_commit = 'local';
-    GRANT EXECUTE ON function pg_catalog.{0} TO "{1}";
-END;$$""".format(f, rewind['username'])
+    GRANT EXECUTE ON function pg_catalog.{0} TO {1};
+END;$$""".format(f, quote_ident(rewind['username'], postgresql.connection()))
                         postgresql.query(sql)
 
                 for name, value in (config.get('users') or {}).items():
@@ -375,6 +429,9 @@ END;$$""".format(f, rewind['username'])
                             postgresql.reload()
                             time.sleep(1)  # give a time to postgres to "reload" configuration files
                             postgresql.connection().close()  # close connection to reconnect with a new password
+                else:  # initdb
+                    # We may want create database and extension for citus
+                    self._postgresql.citus_handler.bootstrap()
         except Exception:
             logger.exception('post_bootstrap')
             task.complete(False)

patroni/postgresql/callback_executor.py

@@ -1,36 +1,76 @@
 import logging
 
-from patroni.postgresql.cancellable import CancellableExecutor
+from enum import Enum
 from threading import Condition, Thread
+from typing import List
+
+from .cancellable import CancellableExecutor, CancellableSubprocess
 
 logger = logging.getLogger(__name__)
 
 
+class CallbackAction(str, Enum):
+    NOOP = "noop"
+    ON_START = "on_start"
+    ON_STOP = "on_stop"
+    ON_RESTART = "on_restart"
+    ON_RELOAD = "on_reload"
+    ON_ROLE_CHANGE = "on_role_change"
+
+    def __repr__(self) -> str:
+        return self.value
+
+
+class OnReloadExecutor(CancellableSubprocess):
+
+    def call_nowait(self, cmd: List[str]) -> None:
+        """Run one `on_reload` callback at most.
+
+        To achieve it we always kill already running command including child processes."""
+        self.cancel(kill=True)
+        self._kill_children()
+        with self._lock:
+            self._start_process(cmd, close_fds=True)
+
+
 class CallbackExecutor(CancellableExecutor, Thread):
 
     def __init__(self):
         CancellableExecutor.__init__(self)
         Thread.__init__(self)
         self.daemon = True
+        self._on_reload_executor = OnReloadExecutor()
         self._cmd = None
         self._condition = Condition()
         self.start()
 
-    def call(self, cmd):
+    def call(self, cmd: List[str]) -> None:
+        """Executes one callback at a time.
+
+        Already running command is killed (including child processes).
+        If it couldn't be killed we wait until it finishes.
+
+        :param cmd: command to be executed"""
+
+        if cmd[-3] == CallbackAction.ON_RELOAD:
+            return self._on_reload_executor.call_nowait(cmd)
+
         self._kill_process()
         with self._condition:
             self._cmd = cmd
             self._condition.notify()
 
-    def run(self):
+    def run(self) -> None:
         while True:
             with self._condition:
                 if self._cmd is None:
                     self._condition.wait()
                 cmd, self._cmd = self._cmd, None
 
-            with self._lock:
-                if not self._start_process(cmd, close_fds=True):
-                    continue
-            self._process.wait()
-            self._kill_children()
+            if cmd is not None:
+                with self._lock:
+                    if not self._start_process(cmd, close_fds=True):
+                        continue
+                if self._process:
+                    self._process.wait()
+                    self._kill_children()