Docker orchestration

> It is fucki*ng hard to create a postgres database without using psql or connect directly to the database.

well ideally you would have a script to create the DB and possibly migrate it. IE this will create a PG database from `DATABASE_URL`

    import dj_database_url
    import psycopg2
    from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT

    config = dj_database_url.config()
    db_conn = psycopg2.connect(host=config['HOST'],
        port=config['PORT'],
        user=config['USER'],
        password=config['PASSWORD'])
    db_conn.set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)

    db_cur = db_conn.cursor()
    db_cur.execute('CREATE DATABASE ' + config['NAME'])

    db_cur.close()
    db_conn.close()

then it's simply a matter of `fig up` + `fig run web python manage.py createdb`

As a point of comparison, an approximation (ie. untested, probably some syntax errors) of the corresponding Ansible tasks:

    - apt: name={{ item }}
      with_items:
        - postgresql-server
        - nginx
    - pip: name={{ item }}
      with_items:
        - flask
        - peewee
    - copy: src=nginx/static dest=/www/ recurse=yes
    - copy: src=nginx/sites_enabled dest=/etc/nginx/ recurse=yes
    - service: name=postgresql state=running enabled=yes
    - service: name=nginx state=running enabled=yes
    - postgresql_user: name=foo password=oof priv=table1,table2
    - file: path=/usr/src/app state=directory
    - copy: src=app.py dest=/usr/src/app/app.py
    - copy: src=templates dest=/usr/src/app/ recurse=yes
    - copy: src=python_app.conf dest=/etc/init/
    - service: name=python_app state=started enabled=yes

Implementation note: this uses an init file for the python app, which will depend upon what OS and init system you're running it under. Also missing handlers for restarting services when config files change.

The post mentions losing database data when doing a "rm". Couldn't you set a volume parameter on the postgres container (to /var/lib/postgres or wherever data is stored) to prevent that? Or am I missing something?

It's a bit of a basic overview of docker-compose. I would have liked to see how to handle more sophisticated patterns such as the data volume container, and how to manage database initialization, both in development and in production.