Change effective on 18 July 2018
heroku.yml now allows you to use the same Docker image for multiple process types.
In the following example, heroku.yml builds one Docker image and uses it for both the
worker process types:
build: docker: web: Dockerfile run: web: bundle exec puma -C config/puma.rb worker: command: python myworker.py image: web
Learn more about Docker builds with heroku.yml.