borgmatic: expose backup frequency interval

[InnovativeInventor]

Description of changes

The previous default Borgmatic systemd files defaults to daily backups. This exposes the option to supply a different backup frequency (e.g. hourly).

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.05 Release Notes (or backporting 22.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[imlonghao]

LGTM

[InnovativeInventor]

@imlonghao is there something I should do to push this PR along, given that it has been approved?

[InnovativeInventor]

@imlonghao is this waiting on you now? Let me know if there is something I can do to help here.

[NickCao]

There are two additional directives in the upstream timer unit that worth handling: Persistent=true and RandomizedDelaySec=3h. They are both useful for backups, persistent allows the timer to be run immediately on next boot if you happen to miss it. While random delay avoids the thundering herd effect of a whole cluster backing up at the same time, stressing the backing storage.

[InnovativeInventor]

There are two additional directives in the upstream timer unit that worth handling: Persistent=true and RandomizedDelaySec=3h. They are both useful for backups, persistent allows the timer to be run immediately on next boot if you happen to miss it. While random delay avoids the thundering herd effect of a whole cluster backing up at the same time, stressing the backing storage.

Ok, what would be the best way for me to add that here? I'm not sure if these options are exposed at the moment.

[NickCao]

Ok, what would be the best way for me to add that here? I'm not sure if these options are exposed at the moment.

Maybe properly defining a timer with systemd.timers.borgmatic, the startAt shorthand is really limiting.

[Janik-Haag]

@InnovativeInventor what do you think about @NickCao suggestion of adding a proper sytemd timer? If you need some example you can look at the restic module. what would be your suggestion if you don't like it?

I would love to get this merged and thank you for your contribution, keep them coming ❤️

[SuperSandro2000]

Suggested change

	Frequency at which borgmatic should be run. See
	{manpage}`systemd.time(7)` for
	options.
	Frequency at which borgmatic should be run.
	See {manpage}`systemd.time(7)` for options.