Allow pg_cron to work on any configured POSTGRES_DB (CircleCI-Public#95)

Due to incorrect ownership of /etc/postgresql/custom-postgresql.conf
the pg_cron.sh script was not able to add POSTGRES_DB to the
`cron.database_name` config. Thus the only DB that would work with
pg_cron is the 'circle_test' DB, as this was hard-coded in the example
file.

This fixes ownership of the files in the /etc/postgresql directory, so
the pg_cron.sh script can run as expected.

Also remove the cron-related lines from custom-postgresql.conf since
pg_cron.sh is adding those two lines and we don't want confusion
around duplicate settings. (Last one wins, for what it's worth.)

Author: stig

Dockerfile.template

@@ -109,6 +109,7 @@ RUN ln -s usr/local/bin/docker-entrypoint.sh /
 RUN chmod +x /usr/local/bin/docker-entrypoint.sh /docker-entrypoint-initdb.d/pg_cron.sh && \
 	mkdir -p /var/lib/postgresql && \
 	chown -R postgres:postgres /var/lib/postgresql && \
+	chown -R postgres:postgres /etc/postgresql && \
 	chown -R postgres:postgres /usr/local/bin/docker-entrypoint.sh
 
 ENTRYPOINT ["docker-entrypoint.sh"]

custom-postgresql.conf

@@ -4,5 +4,3 @@ max_prepared_transactions = 200
 max_locks_per_transaction = 512
 max_pred_locks_per_transaction = 256
 listen_addresses = '*'
-shared_preload_libraries = 'pg_cron'
-cron.database_name = 'circle_test'