Proposal: CCM should store downloaded profiles in git

[gombasg]

Hi,

ccm.conf allows specifying how many old versions of the host profile to keep, but that's not always sufficient. Instead of storing old versions of the profile in distinct directories, I propose to use git to store every version of the profile the host ever downloaded. Advantages:

• Unlimited history, which could still be trimmed with standard git commands should that be needed
• Our experiences show that git's delta compression is extremely efficient on (at least XML) profiles. So having all previous versions stored in git could easily end up taking less space than a single extra version does currently (well, at least if you run "git gc" often enough)
• Having git as a dependency does not sound too heavy, it is widely used, and it could be replaced with any other version control system in the future (or the feature could be disabled, if one does not want to track history)
• There would be no need for ccm-purge anymore

Thoughts?

[stdweird]

some remarks:

• easiest way is to add this to the current structure, instead of fully integrating it (i.e. a separate git repo in parallel with the existing directories; not a replacement of the directories). or did you plan to add the cache dbs in git as well?
• you'll also want a local tool to fetch a profile from this repo and produce the original (or new?) cid directory (not sure if this should)
• please suggest a commit message; i guess it should include the CID or the profile name

having git as a dependency is ok, see also quattor/CAF#191.

[jrha]

Having the commit message the same as the Profile updated message would be nice, e.g.
CID 5 name foobar-sandbox-tkk76468

[jrha]

Discussed at RAL workshop, general agreement for the idea. @gombasg have you done anything towards this already?

[jrha]

@gombasg?