btrfs and snapper with portage on Gentoo

This is just a quick share-a-recipe post to introduce snapper to anybody who hasn’t heard of it, and explain how to use it.

Snapper is a utility that manages btrfs snapshots.  One of the nice features of btrfs is that snapshots are cheap (virtually instant, and consume space only as changes accumulate), and easy to access.  Snapper allows you to automatically create and manage them based on time, events, manual action, etc.

Once snapper is set up you can display a list of snapshots.  I have 10 hourly snapshots, 10 daily snapshots, and snapshots from before/after each emerge.  I can diff them, browse them, etc.  Btrfs snapshots can be browsed right from the filesystem, so if I nuke /etc/passwd I can always do a cp /.snapshots/1875/snapshot/etc/passwd /etc/passwd to restore one from a few hours before (though I do also have /etc in a git repo).

Snapper is currently available in the sunrise overlay – I won’t spend time on how to set that up/etc.  Also, I’ve had time-based snapshots running for a while now and my memory is hazy as to whether I had to do anything to get those working – it just requires sticking some scripts in /etc/cron.*/ and creating a config file containing your policies.

What I did want to post is a recipe for getting pre/post-emerge snapshots working.  All you need to do is add some lines to /etc/portage/bashrc:

case "${EBUILD_PHASE}" in
        preinst) 
                DESC="${CATEGORY}/${PF}"
                NUMBER=`snapper create -t pre -p -d "${DESC}"`
                ;;
        postinst) 
                snapper create -t post --pre-number $NUMBER -d "${DESC}"
                ;;
esac

One of these days I might clean this up a bit and move it to portage.

The Balance of Power in Gentoo

The recent concerns with the request to re-populate QA have re-opened a debate that is a few years old now. I’ve already made some specific recommendations on the lists, but I wanted to step back and explain why I feel the way I do.

Gentoo’s system of governance has some internal ironies – ones which occasionally even lead to calls to establish a benevolent dictator position. I think the mistake that Gentoo makes is that the problem is perceived as being democracy, when in reality the problem is with competing governance bodies with differing constituencies…