first setup of piano-visualizer on pianonix

modules/nixos/default.nix

@@ -2,4 +2,5 @@
   # hydra-auto-upgrade = import ./hydra-auto-upgrade.nix;
   syncthing = import ./syncthing.nix;
   frajulAutoUpgrade = import ./frajul-auto-upgrade.nix;
+  pianoLEDVisualizer = import ./piano-led-visualizer.nix;
 }

modules/nixos/piano-led-visualizer.nix

@@ -0,0 +1,47 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  cfg = config.services.piano-led-visualizer;
+in {
+  options.services.piano-led-visualizer = {
+    enable = lib.mkEnableOption "Enable Piano LED Visualizer";
+
+    user = lib.mkOption {
+      type = lib.types.str;
+      default = "plv";
+      description = "User to run the Piano LED Visualizer service.";
+    };
+
+    group = lib.mkOption {
+      type = lib.types.str;
+      default = "plv";
+      description = "Group to run the Piano LED Visualizer service.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    users.users.${cfg.user} = {
+      isSystemUser = true;
+      group = cfg.group;
+    };
+    users.groups.${cfg.group} = {};
+
+    systemd.services.piano-led-visualizer = {
+      description = "Piano LED Visualizer";
+      after = ["network-online.target"];
+      wants = ["network-online.target"];
+      wantedBy = ["multi-user.target"];
+
+      serviceConfig = {
+        ExecStart = "${pkgs.frajul.piano-led-visualizer}/bin/piano-led-visualizer";
+        Restart = "always";
+        Type = "simple";
+        User = cfg.user;
+        Group = cfg.group;
+      };
+    };
+  };
+}