btrborg

btrbk is good at taking cheap, consistent btrfs snapshots and shipping them to other btrfs volumes. borg is good at deduplicated, encrypted archives on any storage. btrborg connects the two: for every subvolume btrbk manages, it takes the most recent snapshot and stores it in a borg repository of the same name. Because the archive is taken from a read-only snapshot, the backup is consistent even while the live subvolume keeps changing.

The tool has the commands you would expect from a backup job, list, init, create, info, check, prune, compact, and a run that chains them and only prunes if the check passed. Configuration is a shell snippet in /etc/btrborg.conf, so secrets can live in a separate root-only file that is sourced from it, and every variable can also come from the environment. It ships with a man page and is what backs up the studio’s own machines.