manager: make usermgr accessable

machines/manager/users.nix

@@ -30,6 +30,10 @@ with lib;
   };
 
   users.users."root".packages = [
-    (pkgs.callPackage ../../packages/usermgr { })
+    pkgs.usermgr
+  ];
+
+  systemd.tmpfiles.rules = [
+    ''L+ /opt/usermgr - - - - ${pkgs.usermgr}''
   ];
 }

shared/packages.nix

@@ -5,6 +5,8 @@ with lib;
 {
   nixpkgs.overlays = [
     (self: super: {
+      usermgr = self.callPackage ../packages/usermgr { };
+
       scalasca = self.callPackage ../packages/scalasca { };
       scorep = self.callPackage ../packages/scorep { };