Bento
A modularized collection of Packer definitions for building machine images. A good place to start with Packer.
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Buildstep
Buildstep uses Docker and small buildpack scripts to build applications like Heroku. It was used by Dokku to create a 100-line Heroku clone. There are many open source Buildpack scripts for various languages like Java, Ruby, Erlang, PHP, etc.
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