docker-compose.production.yml

# service configuration for production database (Postgres)
db:

  # use stock postgres image
  image: postgres:9.4.5

  # persist the database between containers by storing it in a volume
  volumes:
    - myapp-postgres:/var/lib/postgresql/data

# service configuration for production application server (Unicorn)
app:

  # use the application server image pulled from Docker Hub
  image: madeagency/myapp_app:$DEPLOY_TAG

  # sources environment variable configuration for our app
  env_file: .env

  # rely on the RAILS_ENV value of the host machine
  environment:
    RAILS_ENV: $RAILS_ENV

  # makes the app container aware of the DB container
  links:
    - db

  # persist logs between containers by storing in a volume
  volumes:
    - myapp-logs:/var/www/myapp/log

  # open webapp port for containers only
  expose:
    - '3000'

# service configuration for production web server (Nginx)
web:

  # use the web server image pulled from Docker Hub
  image: madeagency/myapp_web:$DEPLOY_TAG

  # makes the web container aware of the app container
  links:
    - app

  # makes the web container aware of the log volume setup by the app container
  volumes_from:
    - app

  # expose on the host the port we configured Nginx to bind to
  ports:
    - "80:80"