Hi;

I'm implementing etckeeper for all of our servers, but I'm concerned about the "unlimited growth potential" of the /etc/.git repository. (Note: I'm not a git expert by any means.)

Google hasn't explicitly said so, but there are hints that rebasing (followed by garbage collection) will let me squash commits and keep the repository from filling up the root partition.

The command git log --before 'two weeks ago' -1 shows the last commit made just before that point in time, so that may be useful in the final solution.

Also, this post briefly describes the correct process for rebasing: clone /etc repo, edit, and force pull the changes

So, in a nutshell:

  • How can I squash all commits older than (say) two weeks into a single commit at the root of the /etc repo, leaving younger commits alone?

    • This should nuke all the copies of things that were deleted from /etc more than two weeks ago, yes?

  • If I wanted to emulate monthly, weekly and daily backups (with different retention periods) in the etckeeper repository, how could it be done?

Thanks!

2021-11-04

Ok, I'm back, I think I've found a solution:

git checkout master   # To make sure you're where you think you are
root_commit=$(git rev-list --max-parents=0 HEAD)
git log --before "2 weeks ago" -1    # See the commit id and check the date is suitable, don't continue until you're happy

git rebase -i $root_commit   # Starts an editor with a list of every commit since the dawn of time, oldest at the top, latest at the bottom

In the editor, change 'pick' to 'squash' for every commit except:

  • the first (it'll generate an error if you try, as there's nothing to squash it into)
  • the one you found with 'git log', above
  • and all the commits after that

After that, run git gc; it should clear out all the now-unused commits that were squashed.

To emulate weekly/monthly backups, use that git log --before "X weeks/months ago" -1 command to find the commits, and then leave them as 'pick' (not 'squash') during the rebase! :-)

Cautions:

  • This worked for me, but may not work for you. (YMMV)
  • Copy /etc to another directory for experimentation.
  • Back up /etc before you do it for real.
  • If you break it, you get to keep both pieces!

Good luck!

References:

  • https://git-scm.com/book/en/v2/Git-Tools-Rewriting-History
  • https://git-scm.com/docs/git-rebase
  • https://www.cloudbees.com/blog/git-squash-how-to-condense-your-commit-history