nixos/installation-device: remove warning about mdadm

[Stunkymonkey]

Description of changes

discussion from #254807

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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
• Fits CONTRIBUTING.md.

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[ctheune]

Jeesh, I hate mdadm.conf format.

Double checking the man page it shows the syntax without =:

 PROGRAM /usr/sbin/handle-mdadm-events

Did you test your change? I can imagine mdadm being lax about the syntax, but still ...
Is there an existing test you could augment?

[Stunkymonkey]

@ctheune I adjusted the config as you showed.

I did not test this.

[ctheune]

Changing the mdadm stuff has been a bit of a mixed blessing recently and test coverage is quite low.

Please test your changes (we have a check list for that) and also help against future regressions by adding it to e.g. nixos/modules/installer/cd-dvd/installation-cd-base.nix or nixos/tests/installer.nix

[lheckemann]

Given that this is only for installer images, I think it's fine for it not to be tested beyond the existing installation tests -- Maybe it would even make sense to disable the mdmonitor service completely in addition?

@ofborg test installer.swraid

[ctheune]

Disabling the monitor service is basically impossible due to the convoluted structure of the upstream udev rules.

[Stunkymonkey]

ping?

[github-actions]

Successfully created backport PR for release-23.11:

• [Backport release-23.11] nixos/installation-device: remove warning about mdadm #278117