centrifugo: add release note and assertion for compatibility

doc/release-notes/rl-2505.section.md

@@ -110,6 +110,8 @@
 
 - `pkgs.nextcloud28` has been removed since it's out of support upstream.
 
+- `centrifugo` was updated to v6, which uses a new config format. See [upstream documentation](https://centrifugal.dev/docs/getting-started/migration_v6) for migration.
+
 - `teleport` has been upgraded from major version 16 to major version 17.
   Refer to [upstream upgrade instructions](https://goteleport.com/docs/upgrading/overview/)
   and [release notes for v17](https://goteleport.com/docs/changelog/#1701-11152024).

nixos/modules/services/networking/centrifugo.nix

@@ -65,6 +65,14 @@ in
   };
 
   config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion =
+          (lib.versionAtLeast cfg.package.version "6") -> (!(cfg.settings ? name) && !(cfg.settings ? port));
+        message = "`services.centrifugo.settings` is v5 config, must be compatible with centrifugo v6 config format";
+      }
+    ];
+
     systemd.services.centrifugo = {
       description = "Centrifugo messaging server";
       wantedBy = [ "multi-user.target" ];