NixOS comes with systemd, so I've been using it as a first-class part of managing stuff. It's great, especially coming from macOS' launchd.

Which makes it nice to distribute a tool for NixOS so that it can lean into systemd instead of as some bolted-on afterthought.

Makes me wonder what you'd do if you were distributing a lifecycle-heavy tool for Linux users in general since systemd isn't ubiquitous.

I use a systemd timer to run a monthly scrub for my btrfs pool. Kinda cool how you can do increasingly useful things like skip the next scheduled event if the user initiates a scrub, do or don't accumulate tasks if you have a monthly task but the machine was offline for 6 months -- or fold them into a single task, etc.

+1, NixOS makes working with systemd a breeze. Defining units in Nix beats wrangling INI files.

  systemd.services.sync-recyclarr = {
    serviceConfig.Type = "oneshot";
    path = [ pkgs.podman ];
    script = ''
      podman exec -it recyclarr recyclarr sync radarr
      podman exec -it recyclarr recyclarr sync sonarr
    '';
  };
  systemd.timers.sync-recyclarr = {
    timerConfig = {
      OnCalendar = "daily";
      Persistent = true;
      Unit = "sync-recyclarr.service";
    };
    partOf = [ "sync-recyclarr.service" ];
    requires = [ "podman-recyclarr.service" ];
    wantedBy = [ "timers.target" ];
  };

Have you been defining them directly in your flake.nix file? I too am on nixos but I keep all my configurations in their native format and symlink them with nix, that way I can take and reuse that config on a non nixos system easily.

The problem I have found is that nixos doesn't seem to pickup and run systemd timers and services placed into the ~/.config/systems/user folder and additionally things like WantedBy=default.target have no effect.

So after I restart all my services manually on reboot I agree, systems timers are cool.