anchor.diff:  # Use baseimage-docker's init system.
   CMD ["/sbin/my_init"]
   
  -
   ##################################################################################################
   ## START CUSTOMIZATION
   
  +# Create a mount point
   VOLUME ["/srv/pgdata"]
   
   # Install PostgreSQL 9.3.
  
positive.code: # sure you lock down to a specific version, not to `latest`!
  # See https://github.com/phusion/baseimage-docker/blob/master/Changelog.md for
  # a list of version numbers.
  FROM phusion/baseimage:latest
  
  # Set correct environment variables.
  ENV HOME /root
  
negative.code: # START/STOP
  # ==========
  #   $ docker start postgresql
  #   $ docker stop postgresql
  