Etckeeper puts /etc under revision control, git by default, which then behaves like a normal git repository.

All our machines use EtcKeeper, which is installed automatically as part of the AutomatedSystemInstall.

1. Installation

apt-get install etckeeper

etckeeper init
cd /etc
git commit -am "Initial commit"

2. Git commands

The most useful Git commands are:

 git status                      (list of files and their Git states)
 git log                         (see commit dates & commit msgs)
 git log -p [FILE]               (see commits with diff included)
 git add FILE...                 (add FILE to git)
 git diff [FILE]                 (see any differences since last commit)
 git commit FILE...              (commit FILE after modification)
 git checkout FILE...            (override FILE with version from last commit)

3. EtcKeeper usage

Each time you make a change to a file or set of files and are happy with it, commit your change. If you are editing something in /etc/, you should probably be modifying or creating a config package.

It is tempting to use git commit -am "Message ..." which commits all files (-a) and provide the commit message on the command line (-m "..."). While that is tolerable practice, listing specific files on the command line and providing a properly formatted Git commit message is preferred over the "bulk" -am switches.

The reason for this is: the -a switch very often commits other changed files that had nothing to do with your commit, such as modified but not committed changes from other admins, or files automatically generated/modified by DomTool or system scripts.

Those automatically-modified files should be handled in one of the following ways, in order of preference from highest to lowest:

1. If they change often (such as hosts.deny/hosts.allow), move them to /var/tmp/ (or other suitable location) and provide a symlink from /etc/, registering only the symlink in Git.
2. Periodically commit them (just them) with the appropriate commit message (i.e. "Periodic commit of modified files")

3. Remove them from Git (copy them aside, invoke git rm FILE; git commit -am "Remove FILE", and copy them back to expected location

3.1. Notes

EtcKeeper Debian package comes bundled with APT hooks which automatically invoke git commit -a before and after apt-get installs.

This is handy, but this way of pre-apt committing is lame. If there's anything to commit, do it manually. And generally if anything gets committed during the automatic run, it should be just files from category (2) above.

CategorySystemAdministration CategoryNeedsWork