batsignal: add module

.github/CODEOWNERS

@@ -376,6 +376,8 @@ Makefile                                              @thiagokokada
 /modules/services/barrier.nix                         @Kritnich
 /tests/modules/services/barrier                       @Kritnich
 
+/modules/services/batsignal.nix                       @Kranzes
+
 /modules/services/betterlockscreen.nix                @SebTM
 
 /modules/programs/borgmatic.nix                       @DamienCassou

modules/misc/news.nix

@@ -979,6 +979,14 @@ in
           A new module is available: 'programs.hstr'.
         '';
       }
+
+      {
+        time = "2023-04-18T06:28:31+00:00";
+        condition = hostPlatform.isLinux;
+        message = ''
+          A new module is available: 'services.batsignal'.
+        '';
+      }
     ];
   };
 }

modules/modules.nix

@@ -208,6 +208,7 @@ let
     ./services/autorandr.nix
     ./services/avizo.nix
     ./services/barrier.nix
+    ./services/batsignal.nix
     ./services/betterlockscreen.nix
     ./services/blueman-applet.nix
     ./services/borgmatic.nix

modules/services/batsignal.nix

@@ -0,0 +1,50 @@
+{ config, lib, pkgs, ... }:
+
+let
+
+  cfg = config.services.batsignal;
+
+in {
+  meta.maintainers = with lib.maintainers; [ kranzes ];
+
+  options = {
+    services.batsignal = {
+      enable = lib.mkEnableOption "Batsignal Battery Daemon";
+
+      package = lib.mkPackageOption pkgs "batsignal" { };
+
+      extraArgs = lib.mkOption {
+        type = with lib.types; listOf str;
+        default = [ ];
+        description = ''
+          Extra arguments to be passed to the batsignal executable.
+        '';
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      (lib.hm.assertions.assertPlatform "services.batsignal" pkgs
+        lib.platforms.linux)
+    ];
+
+    systemd.user.services.batsignal = {
+      Unit = {
+        Description = "batsignal - battery monitor daemon";
+        After = [ "graphical-session-pre.target" ];
+        PartOf = [ "graphical-session.target" ];
+      };
+
+      Service = {
+        Type = "simple";
+        ExecStart =
+          "${lib.getExe cfg.package} ${lib.escapeShellArgs cfg.extraArgs}";
+        Restart = "on-failure";
+        RestartSec = 1;
+      };
+
+      Install.WantedBy = [ "graphical-session.target" ];
+    };
+  };
+}