Emerald Reverie

Gwmngilfen's blog - Tech, cooking, walking and other randomness from the heart of Scotland

Debian Packaging, the Transparent Way


So I’ve been managing the Debian packages for about 8 months now, and every so often I get asked if there’s anything people can do to help. I have to answer “Not really” because the way we’re building the Debian packages is somewhat arcane.

At least, it was. This blog is to tell you all about how it’s now much more open.

Packaging in the open

The first piece of the puzzle starts with our foreman-rpms repo (github.com/theforeman/foreman-rpms)
in this repo we store all the packaging data for the foreman packages, both deb and rpm. In the case of Debian, you’ll see a structure like:

    debian/<distro>/<type>/<package>

For example, the foreman-proxy nightly package for squeeze is at:

    debian/squeeze/nightly/foreman-proxy

Now, the eagle-eyed and quick-witted among you will already have thought “That’s quite a lot of code duplication”. You’re absolutely correct, but this method allows us to package each distro in it’s own way, if need be. At the moment, it’s all very similar, but it might not stay that way. It also makes it trivial to add in more distributions later (say, quantal or wheezy).

So, now you know where our package data is, you’ll want to know; how does it get used? Well, here we turn to the king of automation - Jenkins.

Jenkins

You can find our Jenkins server at ci.theforeman.org. In there, you will find a set of interesting packaging jobs, specifically:

    packaging_build_foreman-proxy_matrix
    packaging_build_foreman_matrix
    packaging_build_foreman-proxy_individual
    packaging_build_foreman_individual

There’s two types of jobs here. Let’s start with the “individual” jobs. These are what they sound like - they take a set of parameters about what package the are building and build the required package(s). For example, if I feed it the options

    arch = 64bit
    distro = squeeze
    type = nightly

Then it checks out the foreman-rpms repo, and changes to the appropriate directory in the repo, according to those options. It then runs ‘build.sh’ found in the packaging directory, which uses Pbuilder to build the package for the requested settings. At the end of the job (if it built successfully) the package is uploaded to our Debian repository at deb.theforeman.org

The matrix jobs, as you can guess, call the individual jobs many times over - once for all the possible combinations of the options. Thus we can have the matrix job track the Foreman git repo, and rebuild the devel packages whenever a commit is made.

How to get involved

Now that things are more open, it’s easy to get involved. Here’s a workflow you could
use:

1. Get a build box

You don’t have to go through the trouble we did of configuring pbuilder. Just build a
machine with the OS you’d like to run the packages on

2. Install basic packages

You’ll need ‘build-essential’ and ‘devscripts’ as a minimum (well, on Squeeze
anyway :P)

3. Check out the repo

Fork the foreman-rpms repo and check it out to your buildbox. If you’re not trying
to update an existing distro, copy the closest match to a new repo.

4. Build the package

You don’t need to use ‘build.sh’ for this (that’s crafted towards pbuilder and other
small automated task we need to do in the final packages). Just run “debuild -us -uc”
and see if it builds. If it doesn’t either

  a. Install the missing build-dependencies, or
  b. Fix the broken packaging

5. Test

You can either test on your buildbox, or for best results, on another machine with
the same OS installed. Hopefully the package will install and work ;)

6. Contribute

Commit your changes to your repo and send us a pull request on foreman-rpms. We’ll
test your changes and merge if it looks good.

Conclusion

Hopefully that demystifies our package building architecure a bit. If nothing else,
this blog serves to remind me how we set it all up when I can’t remember in six
months time ;)

Epilogue

If anyone is interested in replicating the whole chain, you can get our pbuilder
puppet configuration from our infrstructure repo at github.com/theforeman/foreman-infra

This repo contains the puppet code we use to build the various parts of our
infrastructure, including the Debian build slaves for Jenkins. The only thing you won’t
find there is the GPG key to sign the packages, for obvious reasons ;)