Address PR review: transition to Pending state instead of auto-deleting

When the referenced Server is not found, transition ServerMaintenance to
Pending instead of deleting it. This follows the Kubernetes PVC pattern
where a resource waits in Pending when its dependency is missing, and
keeps the creator responsible for cleanup.

Author: stefanhipfel

internal/controller/servermaintenance_controller.go

@@ -73,6 +73,13 @@ func (r *ServerMaintenanceReconciler) reconcile(ctx context.Context, maintenance
 	server := &metalv1alpha1.Server{}
 	if err := r.Get(ctx, client.ObjectKey{Name: maintenance.Spec.ServerRef.Name}, server); err != nil {
 		if apierrors.IsNotFound(err) {
+			log.V(1).Info("Referenced Server not found, transitioning to Pending state",
+				"ServerMaintenance", client.ObjectKeyFromObject(maintenance),
+				"Server", maintenance.Spec.ServerRef.Name,
+			)
+			if modified, err := r.patchMaintenanceState(ctx, maintenance, metalv1alpha1.ServerMaintenanceStatePending); err != nil || modified {
+				return ctrl.Result{}, err
+			}
 			return ctrl.Result{}, nil
 		}
 		return ctrl.Result{}, fmt.Errorf("failed to get Server: %w", err)

internal/controller/servermaintenance_controller_test.go

@@ -543,6 +543,29 @@ var _ = Describe("ServerMaintenance Controller", func() {
 		Expect(k8sClient.Delete(ctx, serverClaim)).To(Succeed())
 	})
 
+	It("should transition ServerMaintenance to Pending state when its referenced Server no longer exists", func(ctx SpecContext) {
+		By("Creating a ServerMaintenance object")
+		serverMaintenance := &metalv1alpha1.ServerMaintenance{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "test-server-maintenance-orphan",
+				Namespace: ns.Name,
+			},
+			Spec: metalv1alpha1.ServerMaintenanceSpec{
+				ServerRef: &corev1.LocalObjectReference{Name: server.Name},
+				Policy:    metalv1alpha1.ServerMaintenancePolicyEnforced,
+			},
+		}
+		Expect(k8sClient.Create(ctx, serverMaintenance)).To(Succeed())
+		DeferCleanup(k8sClient.Delete, serverMaintenance)
+
+		By("Deleting the Server")
+		Expect(k8sClient.Delete(ctx, server)).To(Succeed())
+		Eventually(Get(server)).ShouldNot(Succeed())
+
+		By("Expecting the ServerMaintenance to transition to Pending state")
+		Eventually(Object(serverMaintenance)).Should(HaveField("Status.State", Equal(metalv1alpha1.ServerMaintenanceStatePending)))
+	})
+
 	It("should complete deletion when the referenced Server is already gone", func(ctx SpecContext) {
 		By("Creating a ServerMaintenance object")
 		serverMaintenance := &metalv1alpha1.ServerMaintenance{