dbus nixos module: add units for systemd user session

This patch makes dbus launch with any user session instead of
leaving it up to the desktop environment launch script to run it.

It has been tested with KDE, which simply uses the running daemon
instead of launching its own.

This is upstream's recommended way to run dbus.

1 files changed, 24 insertions, 0 deletions

diff --git a/nixos/modules/services/system/dbus.nix b/nixos/modules/services/system/dbus.nix
index 77427ce9606..ba34eb25169 100644
--- a/nixos/modules/services/system/dbus.nix
+++ b/nixos/modules/services/system/dbus.nix
@@ -139,6 +139,30 @@ in
 
     systemd.services.dbus.restartTriggers = [ configDir ];
 
+    systemd.user = {
+      services.dbus = {
+        description = "D-Bus User Message Bus";
+        requires = [ "dbus.socket" ];
+        # NixOS doesn't support "Also" so we pull it in manually
+        # As the .service is supposed to come up at the same time as
+        # the .socket, we use basic.target instead of default.target
+        wantedBy = [ "basic.target" ];
+        serviceConfig = {
+          ExecStart = "${pkgs.dbus_daemon}/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation";
+          ExecReload = "${pkgs.dbus_daemon}/bin/dbus-send --print-reply --session --type=method_call --dest=org.freedesktop.DBus / org.freedesktop.DBus.ReloadConfig";
+        };
+      };
+
+      sockets.dbus = {
+        description = "D-Bus User Message Bus Socket";
+        socketConfig = {
+          ListenStream = "%t/bus";
+          ExecStartPost = "-${config.systemd.package}/bin/systemctl --user set-environment DBUS_SESSION_BUS_ADDRESS=unix:path=%t/bus";
+        };
+        wantedBy = [ "sockets.target" ];
+      };
+    };
+
     environment.pathsToLink = [ "/etc/dbus-1" "/share/dbus-1" ];
 
   };