feat(stackable-operator): Add headless/metrics service name functions to RoleGroupRef (#1069)

* Add metrics and headless service name functions to RoleGroupRef

* Better descriptions suggested by reviewer

Co-authored-by: Techassi <git@techassi.dev>

* Update Changelog.md

* Fixing markdown lint

* Pre-commit is happy now

* Update crates/stackable-operator/CHANGELOG.md

Co-authored-by: Techassi <git@techassi.dev>

---------

Co-authored-by: Techassi <git@techassi.dev>
Co-authored-by: Sebastian Bernauer <sebastian.bernauer@stackable.de>

Author: 3 people

crates/stackable-operator/CHANGELOG.md

@@ -31,6 +31,8 @@ All notable changes to this project will be documented in this file.
         fieldPath: spec.nodeName
   ```
 
+- Add associated functions on `RoleGroupRef` to return the rolegroup headless and metrics service name ([#1069]).
+
 ### Changed
 
 - Update `kube` to `1.1.0` ([#1049]).
@@ -51,6 +53,7 @@ All notable changes to this project will be documented in this file.
 [#1060]: https://github.com/stackabletech/operator-rs/pull/1060
 [#1064]: https://github.com/stackabletech/operator-rs/pull/1064
 [#1068]: https://github.com/stackabletech/operator-rs/pull/1068
+[#1069]: https://github.com/stackabletech/operator-rs/pull/1069
 [#1071]: https://github.com/stackabletech/operator-rs/pull/1071
 
 ## [0.93.2] - 2025-05-26

crates/stackable-operator/src/role_utils.rs

@@ -472,6 +472,27 @@ impl<K: Resource> RoleGroupRef<K> {
     pub fn object_name(&self) -> String {
         format!("{}-{}-{}", self.cluster.name, self.role, self.role_group)
     }
+
+    /// Returns the service name used by rolegroups for cluster internal communication only.
+    ///
+    /// The internal use of of this service name is indicated by the `-headless` suffix.
+    /// This service should not be used for communication to external services or clients
+    /// and also should not be used to export metrics (like Prometheus). Metrics should be
+    /// instead exposed via a dedicated service. Use [`Self::rolegroup_metrics_service_name`]
+    /// instead.
+    pub fn rolegroup_headless_service_name(&self) -> String {
+        format!("{name}-headless", name = self.object_name())
+    }
+
+    /// Returns the service name used by rolegroups to expose metrics (like Prometheus).
+    ///
+    /// The use for metrics only is indicated by the `-metrics` suffix. This service
+    /// should not be used for any internal communication or any other external
+    /// communication. For internal communication, use [`Self::rolegroup_headless_service_name`]
+    /// instead.
+    pub fn rolegroup_metrics_service_name(&self) -> String {
+        format!("{name}-metrics", name = self.object_name())
+    }
 }
 
 impl<K: Resource> Display for RoleGroupRef<K> {