#!/bin/sh

set -e
set -o xtrace

export DEBIAN_FRONTEND=noninteractive

cat > "/etc/sysctl.d/10-postgresql-performance.conf" << _EOF_
# See 'http://www.postgresql.org/docs/9.6/static/kernel-resources.html'
# for best practices.
# It is recommended to disable memory overcommit,
# but the Python interpreter may require it on smaller flavors.
# We therefore stick with the heuristic overcommit setting.
vm.overcommit_memory=0

_EOF_

cat > "/etc/rc.local" << _EOF_
#!/bin/bash

# See 'http://www.postgresql.org/docs/9.6/static/kernel-resources.html'
# Postgres 9.6 added support for THP. Using huge pages reduces overhead when
# using large contiguous chunks of memory, like PostgreSQL does.
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
  echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
  echo always > /sys/kernel/mm/transparent_hugepage/enabled
fi

exit \$?

_EOF_

apt-get --allow-unauthenticated -y install postgresql-9.6 postgresql-contrib-9.6 postgresql-server-dev-9.6

sed -i "s/external_pid_file =.*/external_pid_file = '\/var\/run\/postgresql\/postgresql.pid'/" /etc/postgresql/9.6/main/postgresql.conf

# The script will create a postgresql-9.6 image for user to use.
# From Postgresql >9.4, pg_rewind is in the main source tree. But, the default location is
# /usr/lib/postgresql/<version>/bin/pg_rewind. So, there need create a symlink from that
# location to /usr/bin
ln -s /usr/lib/postgresql/9.6/bin/pg_rewind /usr/bin/pg_rewind


# Install the native Python client.
apt-get --allow-unauthenticated -y install libpq-dev python-dev
pip2 install psycopg2