Additional metric: last snapshot date/timestamp(per repository)

Output of rest-server --version

Not relevant.

What should rest-server do differently?

Export the timestamp of the last successful snapshot (and ideally more, I added a few ideas at the end, but last snapshot timestamp is most critical) as part of the Prometheus metrics.

What are you trying to do? What is your use case?

The Prometheus metrics are perfect to set up a monitoring system to alert on backups not running, because it would allow to monitor the actual result of the backup job, so it would be much better than say the backup job itself sending alerts on failures - if the job doesn't run, for example, it might never send out notifications. Watching the REST servers metrics on the other hand would always be able to confirm that everything else aside, the snapshot made it to the repository.

Did rest-server help you today? Did it make you happy in any way?

It's fantastic, and I am currently working on switching a large part of my personal and professional life to back up to a Restic-REST server we run internally (as a rootless Podman service, which is ever so nice) and it's very exciting to have such a clean backup interface. Thank you guys!

Additional metrics that may be useful; some of which I suspect would need the repositories credentials. I am not sure if the REST server would have the capabilities to hook into that. Maybe it could generate metrics during the running of the actual backup command and then store them for the metrics export later, since it can't very well open the repository for each metrics request ?

• HDD/SSD/Whatever storage device metrics (per Repository, as we store our Repos on separate volumes for better isolation) - total size, free size, used size in bytes, maybe optionally some health data like device errors if present ? Useful for obvious reasons such as alerting on low disk space.
• Last backup metrics such as duration, affected files/dirs, maybe things like delta sizes or total files/bytes represented by a snapshot to monitor for suspicious changes in usage patterns such as encryption malware on the client system.
• Date and results of last forget/prune/check commands such as runtime, deleted snapshots, recovered bytes, repacked bytes and so on.

The issue does not name files or tests; start by locating the Prometheus metrics exporter and the repository snapshot-handling entry points. Define the scope around a per-repository metric for the timestamp of the last successful snapshot, and clarify how that state is retained and exposed before considering the additional metric ideas.