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Buildstep wercker status

Heroku-style application builds using Docker and Buildpacks. Used by Dokku to make a mini-Heroku.


  • Docker
  • Git

Supported Buildpacks

Buildpacks should generally just work, but many of them make assumptions about their environment. So Buildstep has a list of officially supported buildpacks that are built-in and ready to be used.

Building Buildstep

The buildstep script uses a buildstep base image that needs to be built. It must be created before you can use the buildstep script. To create it, run:

$ make build

This will create an image called progrium/buildstep that contains all supported buildpacks and the builder script that will actually perform the build using the buildpacks.

Building an App

Running the buildstep script will take an application tar via STDIN and the destination image name as an argument. The tarball is deployed inside a new container based on progrium/buildstep, and the builder script is run in the container. The container is then committed to create an image with the specified name.

$ cat myapp.tar | ./buildstep myapp

If you didn't already have an application tar, you can create one on the fly.

$ tar cC /path/to/your/app . | ./buildstep myapp

The resulting image contains your built app, ready to go. The builder script also parses the Procfile and produces a starter script that takes a process type. Run your app with:

$ docker run -d myapp /bin/bash -c "/start web"

Custom Buildpacks

Custom buildpacks can be installed by committing a file in the root of your git repository named .env This file should contain a line export BUILDPACK_URL=<repository> specifying the git repository providing the buildpack.

If your buildpack needs extra packages these can be installed by the buildpack using bin/compile.