Docker builds with heroku.yml is now in public beta

Change effective on 07 August 2018

heroku.yml is a new manifest for defining your app. Today, support for building Docker images with heroku.yml is in public beta.

build:
  docker:
    web: Dockerfile
run:
  web: bundle exec puma -C config/puma.rb
  worker:
    command:
      - python myworker.py
    image: web

To learn more check out the heroku.yml documentation.