Explore satdiff as potential updater tool

[Popolechien]

SatDiff Tool: https://gitlab.com/likebutter/satdiff
Distribute differential updates to large filesets non-interactively

You can use this tool to update from one version of a fileset to a new version by acquiring only what differs. This is useful when you're bandwidth-constrained or when you're only able to receive static files (e.g. via Satellite downlink).
This tool doesn't care how you get the updates. You simply provide it with a config file and the files you currently have. It'll tell you what new files you'll need to get. You can download them from the Internet, record them from a satellite broadcast, or hand-etch them into a CD-ROM with a laser as your friend dictates bits to you over short-wave radio. Once you've got all the necessary files, SatDiff will compile them into a complete fileset.

Depending on the files in question, this can very efficiently capture differences (or misunderstand them entirely). Plain filesets can generally be expected to work better than binary formats.

[rgaudin]

It's just a thin wrapper over duplicity.
It's possible we'll use something similar for parts of the overall update feature but we're not there yet.