Docker improvements.

Latest greatest upstream (PostgreSQL 9.5, etcd 2.2.5)
Install python packages using requirements file (vs installing from apt-get).

Dockerfile

@@ -12,17 +12,21 @@ RUN curl https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add -
 RUN apt-get update -y
 RUN apt-get upgrade -y
 
-ENV PGVERSION 9.4
-RUN apt-get install python python-yaml python-requests python-boto postgresql-${PGVERSION} python-dnspython python-kazoo python-pip -y
-RUN apt-get install python-dev postgresql-server-dev-${PGVERSION} -y
-RUN pip install python-etcd psycopg2
+ENV PGVERSION 9.5
+RUN apt-get install postgresql-${PGVERSION} postgresql-server-dev-${PGVERSION} -y
+RUN apt-get install python python-dev python-pip -y
+ADD requirements-py2.txt /requirements-py2.txt
+RUN pip install -r /requirements-py2.txt
 
 ENV PATH /usr/lib/postgresql/${PGVERSION}/bin:$PATH
 
 ADD patroni.py /patroni.py
 ADD patroni/ /patroni
 
-ENV ETCDVERSION 2.0.13
+RUN ln -s /patroni.py /usr/local/bin/patroni
+RUN ln -s /patronictl.py /usr/local/bin/patronictl
+
+ENV ETCDVERSION 2.2.5
 RUN curl -L https://github.com/coreos/etcd/releases/download/v${ETCDVERSION}/etcd-v${ETCDVERSION}-linux-amd64.tar.gz | tar xz -C /bin --strip=1 --wildcards --no-anchored etcd etcdctl
 
 ### Setting up a simple script that will serve as an entrypoint

docker/entrypoint.sh

@@ -119,7 +119,8 @@ postgresql:
     archive_command: 'true'
     max_wal_senders: 20
     listen_addresses: 0.0.0.0
-    checkpoint_segments: 64
+    max_wal_size: 1GB
+    min_wal_size: 128MB
     wal_keep_segments: 64
     archive_timeout: 1800s
     max_replication_slots: 20