[atomic-devel] Discussion: How to keep image files in sync across repos

[Stephen Milner <smilner redhat com>]

In the last Atomic Community meeting I noted that keeping image files
in sync across multiple repositories is going to become a support
burden.

  * ACTION: ashcrow jbrooks to start discussion on how to manage
    multiple container repos  (jberkus, 16:19:09)

As an example, the docker/container-engine image files reside in:

- GitHub (CentOS and Fedora in different directories)
- Fedora Repo (Fedora official builds)
- RHEL Repo (RHEL builds)

We consider the Fedora version in GitHub to be the upstream of all
other image file sets. Each repo has it's own standards for inclusion
which change the files slightly. Each also gets slight modifications
over time by their repo owners for version specific bug fixes/standard
updates. Add on that package names/configurations between the OS's may
be different and it becomes clear that adding any bug fixes or
enhancements to one file requires more work to keep files in sync than
one would originally assume. Today we have just a small handful of
these on our plate so we are able to manually keep the files in sync
as we develop them. However, this won't scale as we continue to grow
our images.

Thinking quickly about the problem it seems like having a set of files
upstream which are assembled into image files specific to their down
stream repos would make a lot of sense. These could be generated
either by the repo owners by using the upstream checkout and the
assembly tool or generated by developers.

(tl;dr)
Questions:

- Are there any _existing_tools_ that could help with keeping files
across repos in sync? (aside from git + eyes)
- Are there any _existing_tools_ which would allow us to
generate/populate image files from components?
- Are there any recommend processes already in place that we could
adopt to simplify syncing?

-- 
Thanks,
Steve Milner

Atomic | Red Hat | http://projectatomic.io/