fix: adapt to optional replicas

Author: maltesander

rust/operator-binary/src/controller/build/resource/statefulset.rs

@@ -437,7 +437,9 @@ pub(crate) fn build_metastore_rolegroup_statefulset(
             .build(),
         spec: Some(StatefulSetSpec {
             pod_management_policy: Some("Parallel".to_string()),
-            replicas: Some(i32::from(rg.replicas)),
+            // `None` (no replica count specified) leaves `.spec.replicas` unset so a
+            // HorizontalPodAutoscaler can manage it.
+            replicas: rg.replicas.map(i32::from),
             selector: LabelSelector {
                 match_labels: Some(cluster.role_group_selector(role_group_name).into()),
                 ..LabelSelector::default()

rust/operator-binary/src/controller/validate.rs

@@ -279,7 +279,7 @@ fn validate_role_group_config(
     )?;
 
     Ok(HiveRoleGroupConfig {
-        replicas: merged.replicas.unwrap_or(1),
+        replicas: merged.replicas,
         config: ValidatedMetaStoreConfig::from_merged(merged.config.config, logging),
         config_overrides: merged.config.config_overrides,
         env_overrides,