Don't restart pods on some config changes

api/v1alpha1/conditions.go

@@ -52,7 +52,6 @@ const (
 	ConditionReasonMajorUpdateAvailable ConditionReason = "MajorUpdateAvailable"
 	ConditionReasonVersionOutdated      ConditionReason = "VersionOutdated"
 	ConditionReasonUpgradeCheckFailed   ConditionReason = "UpgradeCheckFailed"
-
 	// ConditionTypeReady indicates that cluster is ready to serve client requests.
 	ConditionTypeReady                      ConditionType   = "Ready"
 	ClickHouseConditionAllShardsReady       ConditionReason = "AllShardsReady"

internal/controller/clickhouse/commands.go

@@ -102,6 +102,34 @@ func (cmd *commander) Version(ctx context.Context, id v1.ClickHouseReplicaID) (s
 	return version, nil
 }
 
+// ReloadConfig executes SYSTEM RELOAD CONFIG.
+func (cmd *commander) ReloadConfig(ctx context.Context, id v1.ClickHouseReplicaID) error {
+	conn, err := cmd.getConn(id)
+	if err != nil {
+		return fmt.Errorf("failed to get connection for replica %s: %w", id, err)
+	}
+
+	if err := conn.Exec(ctx, "SYSTEM RELOAD CONFIG"); err != nil {
+		return fmt.Errorf("reload config on replica %s: %w", id, err)
+	}
+
+	return nil
+}
+
+// ReloadUsers executes SYSTEM RELOAD USERS.
+func (cmd *commander) ReloadUsers(ctx context.Context, id v1.ClickHouseReplicaID) error {
+	conn, err := cmd.getConn(id)
+	if err != nil {
+		return fmt.Errorf("failed to get connection for replica %s: %w", id, err)
+	}
+
+	if err := conn.Exec(ctx, "SYSTEM RELOAD USERS"); err != nil {
+		return fmt.Errorf("reload users on replica %s: %w", id, err)
+	}
+
+	return nil
+}
+
 func (cmd *commander) Databases(ctx context.Context, id v1.ClickHouseReplicaID) (map[string]databaseDescriptor, error) {
 	conn, err := cmd.getConn(id)
 	if err != nil {

internal/controllerutil/annotations.go

@@ -9,7 +9,8 @@ const (
 	AnnotationConfigHash  = "checksum/configuration"
 	AnnotationRestartedAt = "kubectl.kubernetes.io/restartedAt"
 
-	AnnotationStatefulSetVersion = "clickhouse.com/statefulset-version"
+	AnnotationStatefulSetVersion        = "clickhouse.com/statefulset-version"
+	AnnotationRestartRequiredConfigHash = "checksum/restart-required-config"
 )
 
 // AddHashWithKeyToAnnotations adds given spec hash to object's annotations with given key.
@@ -48,3 +49,18 @@ func GetConfigHashFromObject(found client.Object) string {
 func AddObjectConfigHash(obj client.Object, hash string) {
 	AddHashWithKeyToAnnotations(obj, AnnotationConfigHash, hash)
 }
+
+// GetRestartRequiredConfigHashFromObject retrieves restart-required config hash from object's annotations.
+func GetRestartRequiredConfigHashFromObject(found client.Object) string {
+	annotations := found.GetAnnotations()
+	if annotations == nil || annotations[AnnotationRestartRequiredConfigHash] == "" {
+		return ""
+	}
+
+	return annotations[AnnotationRestartRequiredConfigHash]
+}
+
+// AddObjectRestartRequiredConfigHash adds restart-required config hash to object's annotations.
+func AddObjectRestartRequiredConfigHash(obj client.Object, hash string) {
+	AddHashWithKeyToAnnotations(obj, AnnotationRestartRequiredConfigHash, hash)
+}

test/e2e/clickhouse_e2e_test.go

@@ -112,6 +112,84 @@ var _ = Describe("ClickHouse controller", Label("clickhouse"), func() {
 			Entry("scale up to 2 replicas", v1.ClickHouseClusterSpec{Replicas: ptr.To[int32](2)}),
 		)
 
+		It("should not restart pods when only ExtraUsersConfig changes", func(ctx context.Context) {
+			cr := v1.ClickHouseCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: testNamespace,
+					Name:      fmt.Sprintf("test-%d", rand.Uint32()), //nolint:gosec
+				},
+				Spec: v1.ClickHouseClusterSpec{
+					Replicas: ptr.To[int32](1),
+					ContainerTemplate: v1.ContainerTemplateSpec{
+						Image: v1.ContainerImage{Tag: ClickHouseBaseVersion},
+					},
+					DataVolumeClaimSpec: &defaultStorage,
+					KeeperClusterRef:    &corev1.LocalObjectReference{Name: keeper.Name},
+					Settings: v1.ClickHouseSettings{
+						ExtraUsersConfig: runtime.RawExtension{Raw: []byte(`{}`)},
+					},
+				},
+			}
+			checks := 0
+
+			By("creating cluster CR")
+			Expect(k8sClient.Create(ctx, &cr)).To(Succeed())
+			DeferCleanup(func(ctx context.Context) {
+				Expect(k8sClient.Delete(ctx, &cr)).To(Succeed())
+			})
+			WaitClickHouseUpdatedAndReady(ctx, &cr, time.Minute, false)
+			ClickHouseRWChecks(ctx, &cr, &checks)
+
+			By("recording pod UIDs before config change")
+
+			var podsBefore corev1.PodList
+
+			Expect(k8sClient.List(ctx, &podsBefore, client.InNamespace(testNamespace),
+				client.MatchingLabels{controllerutil.LabelAppKey: cr.SpecificName()})).To(Succeed())
+			Expect(podsBefore.Items).NotTo(BeEmpty())
+
+			uidByPodName := make(map[string]types.UID)
+			for _, p := range podsBefore.Items {
+				uidByPodName[p.Name] = p.UID
+			}
+
+			By("updating ExtraUsersConfig (reloadable, should not trigger restart)")
+			Expect(k8sClient.Get(ctx, cr.NamespacedName(), &cr)).To(Succeed())
+			cr.Spec.Settings.ExtraUsersConfig = runtime.RawExtension{
+				Raw: []byte(`{"users": {"e2e_test_user": {"password": "test", "profile": "default"}}}`),
+			}
+			Expect(k8sClient.Update(ctx, &cr)).To(Succeed())
+
+			By("waiting for configuration to sync")
+			EventuallyWithOffset(1, func() bool {
+				var cluster v1.ClickHouseCluster
+
+				ExpectWithOffset(1, k8sClient.Get(ctx, cr.NamespacedName(), &cluster)).To(Succeed())
+
+				for _, cond := range cluster.Status.Conditions {
+					if cond.Type == string(v1.ConditionTypeConfigurationInSync) && cond.Status == metav1.ConditionTrue {
+						return true
+					}
+				}
+
+				return false
+			}, 2*time.Minute).Should(BeTrue())
+
+			By("verifying pods were not restarted (same UIDs)")
+
+			var podsAfter corev1.PodList
+
+			Expect(k8sClient.List(ctx, &podsAfter, client.InNamespace(testNamespace),
+				client.MatchingLabels{controllerutil.LabelAppKey: cr.SpecificName()})).To(Succeed())
+
+			for _, p := range podsAfter.Items {
+				Expect(p.UID).To(Equal(uidByPodName[p.Name]),
+					"pod %s was restarted (UID changed)", p.Name)
+			}
+
+			ClickHouseRWChecks(ctx, &cr, &checks)
+		})
+
 		DescribeTable("ClickHouse cluster updates", func(
 			ctx context.Context,
 			baseReplicas int,