Adds addon env to addon image

[boboldehampsink]

Some addons need env vars on their own image too, to run independently. An example is mysql, which needs at least MYSQL_ROOT_PASSWORD on its on image, see: https://github.com/docker-library/docs/tree/master/mysql#environment-variables

This fix adds the addon env vars to the addon image, fixing this

[busbyjon]

👍

[friism]

testing this now...

[friism]

@boboldehampsink this is not a great solution because it adds the same env to all entries in docker-compose.yml. It's only only needed in the cleardb:

web:
...
  environment:
    PORT: 8080
    MYSQL_DATABASE: cleardb
    MYSQL_ALLOW_EMPTY_PASSWORD: yes
    CLEARDB_DATABASE_URL: 'mysql://root:@cleardb:3306/cleardb'
  links:
    - cleardb
...
cleardb:
  image: mysql
  environment:
    MYSQL_DATABASE: cleardb
    MYSQL_ALLOW_EMPTY_PASSWORD: yes
    CLEARDB_DATABASE_URL: 'mysql://root:@cleardb:3306/cleardb'

Should we add this as an attribute on the image so that addons.js would look like this:

  'cleardb': {
    image: { 
      name: 'mysql',
      env: {
        'MYSQL_DATABASE': 'cleardb',
        'MYSQL_ROOT_PASSWORD': 'my-secret-pw'
      }
    },
    env: {
      'CLEARDB_DATABASE_URL': 'mysql://root:my-secret-pw@cleardb:3306/cleardb'
    }
  }

/cc @hunterloftis

[boboldehampsink]

Yeah that might be better

[friism]

@boboldehampsink do you have time to look at this? I know that this is asking a lot, and it's really on Heroku to make these improvements.

[boboldehampsink]

Sure, i'll try to find some time. Can you assign it to me then?

[friism]

Hm, don't think I can - probably because you're not in the Heroku org.

[boboldehampsink]

Ahh ok, would be cool if that were possible on GitHub ;-)