home-manager.autoUpgrade: add module

Home Manager upgrade service that periodically updates your Nix
channels before running `home-manager switch`.

.github/CODEOWNERS

@@ -292,6 +292,9 @@
 /modules/services/gromit-mpx.nix                      @pjones
 /tests/modules/services/gromit-mpx                    @pjones
 
+/modules/services/home-manager-auto-upgrade.nix       @pinage404
+/tests/modules/services/home-manager-auto-upgrade     @pinage404
+
 /modules/services/hound.nix                           @adisbladis
 
 /modules/services/imapnotify.nix                      @nickhu

modules/lib/maintainers.nix

@@ -193,4 +193,10 @@
     githubId = 9267430;
     name = "Philipp Mildenberger";
   };
+  pinage404 = {
+    name = "pinage404";
+    email = "pinage404@gmail.com";
+    github = "pinage404";
+    githubId = 6325757;
+  };
 }

modules/modules.nix

@@ -185,6 +185,7 @@ let
     ./services/gpg-agent.nix
     ./services/grobi.nix
     ./services/gromit-mpx.nix
+    ./services/home-manager-auto-upgrade.nix
     ./services/hound.nix
     ./services/imapnotify.nix
     ./services/kanshi.nix

modules/services/home-manager-auto-upgrade.nix

@@ -0,0 +1,69 @@
+{ config, lib, pkgs, ... }:
+
+let
+
+  cfg = config.services.home-manager.autoUpgrade;
+
+  homeManagerPackage = pkgs.callPackage ../../home-manager {
+    path = config.programs.home-manager.path;
+  };
+
+in {
+  meta.maintainers = [ lib.hm.maintainers.pinage404 ];
+
+  options = {
+    services.home-manager.autoUpgrade = {
+      enable = lib.mkEnableOption ''
+        the Home Manager upgrade service that periodically updates your Nix
+        channels before running <code>home-manager switch</code>'';
+
+      frequency = lib.mkOption {
+        type = lib.types.str;
+        example = "weekly";
+        description = ''
+          The interval at which the Home Manager auto upgrade is run.
+          This value is passed to the systemd timer configuration
+          as the <code>OnCalendar</code> option.
+          The format is described in
+          <citerefentry>
+            <refentrytitle>systemd.time</refentrytitle>
+            <manvolnum>7</manvolnum>
+          </citerefentry>.
+        '';
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      (lib.hm.assertions.assertPlatform "services.home-manager.autoUpgrade" pkgs
+        lib.platforms.linux)
+    ];
+
+    systemd.user = {
+      timers.home-manager-auto-upgrade = {
+        Unit.Description = "Home Manager upgrade timer";
+
+        Install.WantedBy = [ "timers.target" ];
+
+        Timer = {
+          OnCalendar = cfg.frequency;
+          Unit = "home-manager-auto-upgrade.service";
+          Persistent = true;
+        };
+      };
+
+      services.home-manager-auto-upgrade = {
+        Unit.Description = "Home Manager upgrade";
+
+        Service.ExecStart = toString
+          (pkgs.writeShellScript "home-manager-auto-upgrade" ''
+            echo "Update Nix's channels"
+            ${pkgs.nix}/bin/nix-channel --update
+            echo "Upgrade Home Manager"
+            ${homeManagerPackage}/bin/home-manager switch
+          '');
+      };
+    };
+  };
+}

tests/default.nix

@@ -143,6 +143,7 @@ import nmt {
     ./modules/services/git-sync
     ./modules/services/gpg-agent
     ./modules/services/gromit-mpx
+    ./modules/services/home-manager-auto-upgrade
     ./modules/services/kanshi
     ./modules/services/lieer
     ./modules/services/pantalaimon

tests/modules/services/home-manager-auto-upgrade/basic-configuration.nix

@@ -0,0 +1,18 @@
+{ config, ... }:
+
+{
+  config = {
+    services.home-manager.autoUpgrade = {
+      enable = true;
+      frequency = "00:00";
+    };
+
+    nmt.script = ''
+      serviceFile=home-files/.config/systemd/user/home-manager-auto-upgrade.service
+      assertFileExists $serviceFile
+
+      timerFile=home-files/.config/systemd/user/home-manager-auto-upgrade.timer
+      assertFileExists $timerFile
+    '';
+  };
+}

tests/modules/services/home-manager-auto-upgrade/default.nix

@@ -0,0 +1 @@
+{ home-manager-auto-upgrade-basic-configuration = ./basic-configuration.nix; }