You need to install Heroku Docker CLI plugin.
$ heroku plugins:install heroku-docker$ echo 'web: ./nginx-start.sh' > Procfile
$ mkdir www
$ echo '<html><body><h1>It works</h1></body></html>' > www/index.html
$ heroku docker:init --image atsnngs/heroku-nginx
$ docker-compose build$ docker-compose up web
$ open "http://$(docker-machine ip default):8080"$ heroku create
$ heroku docker:release
$ heroku open