Make nginx uid and gid optional.

modules/misc/ids.nix

@@ -74,6 +74,7 @@ in
     wwwrun = 54;
     spamd = 56;
     nslcd = 58;
+    nginx = 60;
 
     # When adding a uid, make sure it doesn't match an existing gid.
 
@@ -131,6 +132,7 @@ in
     networkmanager = 57;
     nslcd = 58;
     scanner = 59;
+    nginx = 60;
 
     # When adding a gid, make sure it doesn't match an existing uid.
 

modules/services/web-servers/nginx/default.nix

@@ -74,10 +74,14 @@ in
       };
     };
 
-    users.extraUsers.nginx = {
+    users.extraUsers = optionalAttrs (cfg.user == "nginx") singleton
+    { name = "nginx";
       group = "nginx";
+      uid = config.ids.uids.nginx;
     };
 
-    users.extraGroups.nginx = {};
-  };
+    users.extraGroups = optionalAttrs (cfg.group == "nginx") singleton
+    { name = "nginx";
+      gid = config.ids.gids.nginx;
+    };
 }