Track your configuration using git

I have a confession to make: etckeeper got me spoiled. I really like ability to track changes in git and have it documented in git log. However, this time I was working on already installed machine which didn't have much files in /etc for etckeeper, but I wanted to have peace of mind with configuration in git.

This got me thinking: I could create git in root (/) of file-system and than track any file using it. Since this is three servers I could also use other two nodes to make a backup of configuration by pushing to them.

To make this working first I need to do init git repository and create branch with same name as short version of hostname (this will allow us to push and pull with unique branch name on each machine):

# cd /
# git init
# git checkout -b $( hostname -s )
With this done, all I have to do now is add and commit a file that I want to change (to preserve original version), make changes and commit it after change. To make first step easier, I created script which allows me to do git ac /path/to/file that will add file to git and commit original version in just one command (ac = add+commit).
# cat /usr/local/bin/git-ac

git add $*
git commit -m $1 $*
With this in place, I now have nice log of one server. Now it's time to repeat it on each machine and use git remote add host1 host1:/.git to add other hosts.

Since I have some commits in branch with short hostname, it's also right moment to issue git branch -d master to remove master branch which we don't use (and will clutter out output later).

We can fetch branches from other servers manually, but since we already have that information in git remote I wrote another quick script:

# cat /usr/local/bin/git-f
git remote | xargs -i git fetch {}
With this I can issue just git f to fetch all branches on all hosts. If I want to push changes to other nodes, I can do git p which is similar script:
# cat /usr/local/bin/git-p
# disable push with git remote set-url --push pg-edu no_push

git remote | xargs -i git push {} $( hostname -s )
There is also a note how to disable push to some remote (if you don't want to have full history there, but want to pull from it).

With this in place, you will get nice log of changes in git, and since every host hast branch of all other hosts, you can even use git cherry-pick to get same change on multiple hosts. Last useful hint is to use git branch -va which will show all branches together with sha of last commit which can be used to cherry pick last commit. If you need older commits, you can always issue git log on remote branch and pick up commit that you need.

Last step is to add cron job in cron.daily to commit changes daily which you forgot to commit:

# cat /etc/cron.daily/cron-commit

cd /
git commit -m $( date +%Y-%m-%dT%H%M%S ) -a
With everything documented here, you have easy to use git in which you can track changes of any file on your file-system. There is one additional note: if file that you want to track is on nfs mount, you will need to add and commit it from outside of nfs mount (specifying full path to file on nfs) because if you are inside nfs mount git will complain that there is no git repository there.