sway: Manage waybar with systemd

users/simon/modules/sway.nix

@@ -164,9 +164,7 @@ lib.mkIf nixosConfig.sbruder.gui.enable {
         "--locked ${cfg.modifier}+q" = ''exec 'test $(swaymsg -t get_outputs | ${pkgs.jq}/bin/jq "[.[].dpms] | any") = "true" && swaymsg "output * dpms off" || swaymsg "output * dpms on"'';
       };
 
-      bars = [
-        { command = "waybar"; }
-      ];
+      bars = [ ]; # managed as systemd user unit
 
       assigns = {
         "2" = [
@@ -253,7 +251,6 @@ lib.mkIf nixosConfig.sbruder.gui.enable {
     alacritty # terminal
     brightnessctl # control screen brightness
     sway-contrib.grimshot # screenshots
-    (waybar.override { pulseSupport = true; }) # better status bar FIXME: Remove override with 21.03 (https://github.com/NixOS/nixpkgs/pull/98490)
     wdisplays # graphical output manager
   ];
 
@@ -460,6 +457,26 @@ lib.mkIf nixosConfig.sbruder.gui.enable {
     '';
   };
 
+  systemd.user.services.waybar = {
+    Unit = {
+      Description = "Highly customizable Wayland bar for Sway and Wlroots based compositors.";
+      Documentation = "https://github.com/Alexays/Waybar/wiki/";
+      PartOf = [ "sway-session.target" ];
+    };
+
+    Install.WantedBy = [ "sway-session.target" ];
+
+    Service = {
+      # ensure sway is already started, otherwise workspaces will not work
+      ExecStartPre = "${config.wayland.windowManager.sway.package}/bin/swaymsg";
+      # FIXME: Remove override with 21.05 (https://github.com/NixOS/nixpkgs/pull/98490)
+      ExecStart = "${pkgs.waybar.override { pulseSupport = true; }}/bin/waybar";
+      ExecReload = "${pkgs.utillinux}/bin/kill -SIGUSR2 $MAINPID";
+      Restart = "on-failure";
+      RestartSec = "1s";
+    };
+  };
+
   programs.mako = {
     enable = true;