Heroku add-ons may now be attached across applications and multiple times on a single app.

Change effective on 04 May 2015

For add-ons that are enabled to be attached, they can be attached to another application by running the command:

$ heroku addons:attach ADDON_NAME -a APP_NAME

For add-ons that are enabled to be added multiple times they can be added just as you would normally create an add-on:

$ heroku addons:create heroku-postgresql

Additionally you may now set the alias that your add-on attaches to by using the --as flag. For example, attaching as follows sets the var API_DATABASE_URL:

$ heroku addons:create heroku-postgresql --as API_DATABASE

Finally, the CLI now supports the use of create and destroy in place of adding and removing add-ons to better align with Heroku CLI commands.