nixos/systemd-lock-handler: init

2 files changed, 74 insertions, 0 deletions

diff --git a/nixos/modules/services/system/systemd-lock-handler.md b/nixos/modules/services/system/systemd-lock-handler.md
new file mode 100644
index 0000000000000..ac9ee00ae4bcc
--- /dev/null
+++ b/nixos/modules/services/system/systemd-lock-handler.md
@@ -0,0 +1,47 @@
+# systemd-lock-handler {#module-services-systemd-lock-handler}
+
+The `systemd-lock-handler` module provides a service that bridges
+D-Bus events from `logind` to user-level systemd targets:
+
+  - `lock.target` started by `loginctl lock-session`,
+  - `unlock.target` started by `loginctl unlock-session` and
+  - `sleep.target` started by `systemctl suspend`.
+
+You can create a user service that starts with any of these targets.
+
+For example, to create a service for `swaylock`:
+
+```nix
+{
+  services.systemd-lock-handler.enable = true;
+
+  systemd.user.services.swaylock = {
+    description = "Screen locker for Wayland";
+    documentation = ["man:swaylock(1)"];
+
+    # If swaylock exits cleanly, unlock the session:
+    onSuccess = ["unlock.target"];
+
+    # When lock.target is stopped, stops this too:
+    partOf = ["lock.target"];
+
+    # Delay lock.target until this service is ready:
+    before = ["lock.target"];
+    wantedBy = ["lock.target"];
+
+    serviceConfig = {
+      # systemd will consider this service started when swaylock forks...
+      Type = "forking";
+
+      # ... and swaylock will fork only after it has locked the screen.
+      ExecStart = "${lib.getExe pkgs.swaylock} -f";
+
+      # If swaylock crashes, always restart it immediately:
+      Restart = "on-failure";
+      RestartSec = 0;
+    };
+  };
+}
+```
+
+See [upstream documentation](https://sr.ht/~whynothugo/systemd-lock-handler) for more information.
diff --git a/nixos/modules/services/system/systemd-lock-handler.nix b/nixos/modules/services/system/systemd-lock-handler.nix
new file mode 100644
index 0000000000000..1ecb13b75bb3e
--- /dev/null
+++ b/nixos/modules/services/system/systemd-lock-handler.nix
@@ -0,0 +1,27 @@
+{ config
+, pkgs
+, lib
+, ...
+}:
+let
+  cfg = config.services.systemd-lock-handler;
+  inherit (lib) mkIf mkEnableOption mkPackageOption;
+in
+{
+  options.services.systemd-lock-handler = {
+    enable = mkEnableOption (lib.mdDoc "systemd-lock-handler");
+    package = mkPackageOption pkgs "systemd-lock-handler" { };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.packages = [ cfg.package ];
+
+    # https://github.com/NixOS/nixpkgs/issues/81138
+    systemd.user.services.systemd-lock-handler.wantedBy = [ "default.target" ];
+  };
+
+  meta = {
+    maintainers = with lib.maintainers; [ liff ];
+    doc = ./systemd-lock-handler.md;
+  };
+}