Add topologySpreadConstraints configuration to pod spec.

e2e/tests/test_e2e.py

@@ -1646,7 +1646,6 @@ class EndToEndTestCase(unittest.TestCase):
         # toggle pod anti affinity to move replica away from master node
         self.assert_distributed_pods(master_nodes)
 
-
     @timeout_decorator.timeout(TEST_TIMEOUT_SEC)
     def test_overwrite_pooler_deployment(self):
         pooler_name = 'acid-minimal-cluster-pooler'
@@ -2385,6 +2384,56 @@ class EndToEndTestCase(unittest.TestCase):
         # toggle pod anti affinity to move replica away from master node
         self.assert_distributed_pods(master_nodes)
 
+    @timeout_decorator.timeout(TEST_TIMEOUT_SEC)
+    def test_topology_spread_constraints(self):
+        '''
+            Enable topologySpreadConstraints for pods
+        '''
+        k8s = self.k8s
+        cluster_labels = "application=spilo,cluster-name=acid-minimal-cluster"
+
+        # Verify we are in good state from potential previous tests
+        self.eventuallyEqual(lambda: k8s.count_running_pods(), 2, "No 2 pods running")
+
+        master_nodes, replica_nodes = k8s.get_cluster_nodes()
+        self.assertNotEqual(master_nodes, [])
+        self.assertNotEqual(replica_nodes, [])
+
+        # Patch label to nodes for topologySpreadConstraints
+        patch_node_label = {
+            "metadata": {
+                "labels": {
+                    "topology.kubernetes.io/zone": "zalando"
+                }
+            }
+        }
+        k8s.api.core_v1.patch_node(master_nodes[0], patch_node_label)
+        k8s.api.core_v1.patch_node(replica_nodes[0], patch_node_label)
+
+        # Scale-out postgresql pods
+        k8s.api.custom_objects_api.patch_namespaced_custom_object("acid.zalan.do", "v1", "default", "postgresqls", "acid-minimal-cluster",
+            {"spec": {"numberOfInstances": 6}})
+        self.eventuallyEqual(lambda: k8s.get_operator_state(), {"0": "idle"}, "Operator does not get in sync")
+        self.eventuallyEqual(lambda: k8s.count_pods_with_label(cluster_labels), 6, "Postgresql StatefulSet are scale to 6")
+        self.eventuallyEqual(lambda: k8s.count_running_pods(), 6, "All pods are running")
+
+        worker_node_1 = 0
+        worker_node_2 = 0
+        pods = k8s.api.core_v1.list_namespaced_pod('default', label_selector=cluster_labels)
+        for pod in pods.items:
+            if pod.spec.node_name == 'postgres-operator-e2e-tests-worker':
+                worker_node_1 += 1
+            elif pod.spec.node_name == 'postgres-operator-e2e-tests-worker2':
+                worker_node_2 += 1
+
+        self.assertEqual(worker_node_1, worker_node_2)
+        self.assertEqual(worker_node_1, 3)
+        self.assertEqual(worker_node_2, 3)
+
+        # Scale-it postgresql pods to previous replicas
+        k8s.api.custom_objects_api.patch_namespaced_custom_object("acid.zalan.do", "v1", "default", "postgresqls", "acid-minimal-cluster",
+            {"spec": {"numberOfInstances": 2}})
+
     @timeout_decorator.timeout(TEST_TIMEOUT_SEC)
     def test_zz_cluster_deletion(self):
         '''
@@ -2460,7 +2509,7 @@ class EndToEndTestCase(unittest.TestCase):
             self.eventuallyEqual(lambda: k8s.count_deployments_with_label(cluster_label), 0, "Deployments not deleted")
             self.eventuallyEqual(lambda: k8s.count_pdbs_with_label(cluster_label), 0, "Pod disruption budget not deleted")
             self.eventuallyEqual(lambda: k8s.count_secrets_with_label(cluster_label), 8, "Secrets were deleted although disabled in config")
-            self.eventuallyEqual(lambda: k8s.count_pvcs_with_label(cluster_label), 3, "PVCs were deleted although disabled in config")
+            self.eventuallyEqual(lambda: k8s.count_pvcs_with_label(cluster_label), 6, "PVCs were deleted although disabled in config")
 
         except timeout_decorator.TimeoutError:
             print('Operator log: {}'.format(k8s.get_operator_log()))

manifests/postgresql.crd.yaml

@@ -582,6 +582,12 @@ spec:
                         - PreferNoSchedule
                     tolerationSeconds:
                       type: integer
+              topologySpreadConstraints:
+                type: array
+                nullable: true
+                items:
+                  type: object
+                  x-kubernetes-preserve-unknown-fields: true
               useLoadBalancer:
                 type: boolean
                 description: deprecated

pkg/apis/acid.zalan.do/v1/crds.go

@@ -895,6 +895,16 @@ var PostgresCRDResourceValidation = apiextv1.CustomResourceValidation{
 							},
 						},
 					},
+					"topologySpreadConstraints": {
+						Type:     "array",
+						Nullable: true,
+						Items: &apiextv1.JSONSchemaPropsOrArray{
+							Schema: &apiextv1.JSONSchemaProps{
+								Type:                   "object",
+								XPreserveUnknownFields: util.True(),
+							},
+						},
+					},
 					"useLoadBalancer": {
 						Type:        "boolean",
 						Description: "deprecated",

pkg/apis/acid.zalan.do/v1/postgresql_type.go

@@ -70,6 +70,7 @@ type PostgresSpec struct {
 	PreparedDatabases         map[string]PreparedDatabase   `json:"preparedDatabases,omitempty"`
 	SchedulerName             *string                       `json:"schedulerName,omitempty"`
 	NodeAffinity              *v1.NodeAffinity              `json:"nodeAffinity,omitempty"`
+	TopologySpreadConstraints []v1.TopologySpreadConstraint `json:"topologySpreadConstraints,omitempty"`
 	Tolerations               []v1.Toleration               `json:"tolerations,omitempty"`
 	Sidecars                  []Sidecar                     `json:"sidecars,omitempty"`
 	InitContainers            []v1.Container                `json:"initContainers,omitempty"`

pkg/cluster/cluster.go

@@ -499,6 +499,11 @@ func (c *Cluster) compareStatefulSetWith(statefulSet *appsv1.StatefulSet) *compa
 		needsRollUpdate = true
 		reasons = append(reasons, "new statefulset's pod affinity does not match the current one")
 	}
+	if !reflect.DeepEqual(c.Statefulset.Spec.Template.Spec.TopologySpreadConstraints, statefulSet.Spec.Template.Spec.TopologySpreadConstraints) {
+		needsReplace = true
+		needsRollUpdate = true
+		reasons = append(reasons, "new statefulset's pod topologySpreadConstraints does not match the current one")
+	}
 	if len(c.Statefulset.Spec.Template.Spec.Tolerations) != len(statefulSet.Spec.Template.Spec.Tolerations) {
 		needsReplace = true
 		needsRollUpdate = true

pkg/cluster/k8sres.go

@@ -604,6 +604,13 @@ func generatePodAntiAffinity(podAffinityTerm v1.PodAffinityTerm, preferredDuring
 	return podAntiAffinity
 }
 
+func generateTopologySpreadConstraints(labels labels.Set, topologySpreadConstraints []v1.TopologySpreadConstraint) []v1.TopologySpreadConstraint {
+	for _, topologySpreadConstraint := range topologySpreadConstraints {
+		topologySpreadConstraint.LabelSelector = &metav1.LabelSelector{MatchLabels: labels}
+	}
+	return topologySpreadConstraints
+}
+
 func tolerations(tolerationsSpec *[]v1.Toleration, podToleration map[string]string) []v1.Toleration {
 	// allow to override tolerations by postgresql manifest
 	if len(*tolerationsSpec) > 0 {
@@ -809,6 +816,7 @@ func (c *Cluster) generatePodTemplate(
 	initContainers []v1.Container,
 	sidecarContainers []v1.Container,
 	sharePgSocketWithSidecars *bool,
+	topologySpreadConstraintsSpec []v1.TopologySpreadConstraint,
 	tolerationsSpec *[]v1.Toleration,
 	spiloRunAsUser *int64,
 	spiloRunAsGroup *int64,
@@ -878,6 +886,10 @@ func (c *Cluster) generatePodTemplate(
 		podSpec.PriorityClassName = priorityClassName
 	}
 
+	if len(topologySpreadConstraintsSpec) > 0 {
+		podSpec.TopologySpreadConstraints = generateTopologySpreadConstraints(labels, topologySpreadConstraintsSpec)
+	}
+
 	if sharePgSocketWithSidecars != nil && *sharePgSocketWithSidecars {
 		addVarRunVolume(&podSpec)
 	}
@@ -1469,6 +1481,7 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 		initContainers,
 		sidecarContainers,
 		c.OpConfig.SharePgSocketWithSidecars,
+		spec.TopologySpreadConstraints,
 		&tolerationSpec,
 		effectiveRunAsUser,
 		effectiveRunAsGroup,
@@ -2356,6 +2369,7 @@ func (c *Cluster) generateLogicalBackupJob() (*batchv1.CronJob, error) {
 		[]v1.Container{},
 		[]v1.Container{},
 		util.False(),
+		[]v1.TopologySpreadConstraint{},
 		&tolerationsSpec,
 		nil,
 		nil,

pkg/cluster/k8sres_test.go

@@ -3984,3 +3984,46 @@ func TestGenerateCapabilities(t *testing.T) {
 		}
 	}
 }
+
+func TestTopologySpreadConstraints(t *testing.T) {
+	clusterName := "acid-test-cluster"
+	namespace := "default"
+
+	pg := acidv1.Postgresql{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      clusterName,
+			Namespace: namespace,
+		},
+		Spec: acidv1.PostgresSpec{
+			NumberOfInstances: 1,
+			Resources: &acidv1.Resources{
+				ResourceRequests: acidv1.ResourceDescription{CPU: k8sutil.StringToPointer("1"), Memory: k8sutil.StringToPointer("10")},
+				ResourceLimits:   acidv1.ResourceDescription{CPU: k8sutil.StringToPointer("1"), Memory: k8sutil.StringToPointer("10")},
+			},
+			Volume: acidv1.Volume{
+				Size: "1G",
+			},
+		},
+	}
+
+	cluster := New(
+		Config{
+			OpConfig: config.Config{
+				PodManagementPolicy: "ordered_ready",
+			},
+		}, k8sutil.KubernetesClient{}, acidv1.Postgresql{}, logger, eventRecorder)
+	cluster.Name = clusterName
+	cluster.Namespace = namespace
+	cluster.labelsSet(true)
+
+	s, err := cluster.generateStatefulSet(&pg.Spec)
+	assert.NoError(t, err)
+	assert.Contains(t, s.Spec.Template.Spec.TopologySpreadConstraints, v1.TopologySpreadConstraint{
+		MaxSkew:           int32(1),
+		TopologyKey:       "topology.kubernetes.io/zone",
+		WhenUnsatisfiable: v1.DoNotSchedule,
+		LabelSelector: &metav1.LabelSelector{
+			MatchLabels: cluster.labelsSet(true),
+		},
+	})
+}