Add support for PartOf dependencies

modules/system/boot/systemd-unit-options.nix

@@ -47,6 +47,15 @@ with pkgs.lib;
       '';
     };
 
+    partOf = mkOption {
+      default = [];
+      types = types.listOf types.string;
+      description = ''
+        If the specified units are stopped or restarted, then this
+        unit is stopped or restarted as well.
+      '';
+    };
+
     wantedBy = mkOption {
       default = [];
       types = types.listOf types.string;

modules/system/boot/systemd.nix

@@ -191,8 +191,9 @@ let
           ''}
           Requires=${concatStringsSep " " def.requires}
           Wants=${concatStringsSep " " def.wants}
-          Before=${concatStringsSep " " def.before}
           After=${concatStringsSep " " def.after}
+          Before=${concatStringsSep " " def.before}
+          PartOf=${concatStringsSep " " def.partOf}
           ${def.unitConfig}
 
           [Service]

modules/system/upstart/upstart.nix

@@ -54,17 +54,20 @@ let
         '';
     in {
 
-      inherit (job) description requires wants before environment path;
+      inherit (job) description requires wants before partOf environment path;
 
       after =
         (if job.startOn == "stopped udevtrigger" then [ "systemd-udev-settle.service" ] else
          if job.startOn == "started udev" then [ "systemd-udev.service" ] else
-         if job.startOn == "" || job.startOn == "startup" then [ ] else
+         if job.startOn == "ip-up" then [] else
+         if job.startOn == "" || job.startOn == "startup" then [] else
          builtins.trace "Warning: job ‘${job.name}’ has unknown startOn value ‘${job.startOn}’." []
         ) ++ job.after;
 
       wantedBy =
-        (if job.startOn == "" then [ ] else [ "multi-user.target" ]) ++ job.wantedBy;
+        (if job.startOn == "" then [] else
+         if job.startOn == "ip-up" then [ "ip-up.target" ] else
+         [ "multi-user.target" ]) ++ job.wantedBy;
 
       serviceConfig =
         ''