EZBake - A new way to converge docker containers with chef

May 13, 2014   

EZ Bake came from an idea I had while watching the HangOps episode 2014-04-11 in which they were talking about Docker and Config Management being complementary rather than adversary.

I have expermented with using Chef and Docker together in the past but wanted to tackle the problem from a slightly different angle. I’ve recently been working on some PAAS stuff, both Deis and Solum these both utilize the tooling from Flynn which builds heroku style buildpacks in Docker.

EZ Bake takes chef recipes designed for chef-solo ( but could easily be extended to do the same for chef-zero, or chef-client with a server) in a tarball via stdin and converges a docker node using that recipe.

This methodology seems a little weird at first, but it gives you the ability to ship your Chef cookbooks as self-contained tarballs, or even more interestingly use the git archive command from your git repository to do this automatically and then pipe that directly to the docker run command.

In order to recognize and run your cookbook ( or repo ) it needs to contain the following files: Berksfile, solo.json, solo.rb in the root of your cookbook. There is some provision for providing different locations for these via environment variables. This is pre-ChefDK and will probably become easier with ChefDK.

I have provided an example in the ezbake repo that will install Java7 in the container.

This example shows:

  • Converging a container using a local chef recipe
  • Committing the container to an image on completion
  • Removing the build container
  • Running the new image

    $ git clone paulczar/ezbake
    $ cd ezbake/examples
    $ ID=$(tar cf - . | sudo docker run -i -a stdin paulczar/ezbake) \
    && sudo docker attach $ID \
    && sudo docker commit $ID java7 
    && sudo docker rm $ID
    Running Berkshelf to collect your cookbooks:
    Installing java (1.22.0) from site: 'http://cookbooks.opscode.com/api/v1/cookbooks'
    Converging your container:
    [2014-04-12T22:10:24+00:00] INFO: Forking chef instance to converge...
    [2014-04-12T22:16:52+00:00] INFO: Chef Run complete in 154.563192281 seconds
    [2014-04-12T22:16:52+00:00] INFO: Running report handlers
    [2014-04-12T22:16:52+00:00] INFO: Report handlers complete
    $ sudo docker run -t java7 java -version
    java version "1.7.0_51"
    Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
    Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)

This could easily be built into a CI pipeline. a git webhook could call jenkins which would clone the repo and then use a command like git archive master | docker run -i -a stdin paulczar/ezbake to converge a container from it.

It could also very easily be used in Deis or Solum as an alternative to a Heroku buildpack.

comments powered by Disqus