Heroku's Cedar stack as a Docker image.
Using this image will include the base Cedar stack image and use Heroku's default buildpacks to turn application code into a production image.
$ cat Dockerfile
FROM convox/cedar
$ docker build -t cedar-app .
Sending build context to Docker daemon
Step 0 : FROM convox/cedar
...
-----> Compiling for Ruby
-----> Compiling Ruby/Rails
-----> Installing dependencies using 1.7.12
Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
$ docker run cedar-app rails start
=> Rails application starting on http://0.0.0.0:3000
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