Add topologySpreadConstraints configuration to pod spec.

e2e/tests/test_e2e.py

@@ -559,7 +559,7 @@ def compare_config():
 
             pg_patch_config["spec"]["patroni"]["slots"][slot_to_change]["database"] = "bar"
             del pg_patch_config["spec"]["patroni"]["slots"][slot_to_remove]
-            
+
             k8s.api.custom_objects_api.patch_namespaced_custom_object(
                 "acid.zalan.do", "v1", "default", "postgresqls", "acid-minimal-cluster", pg_delete_slot_patch)
 
@@ -576,7 +576,7 @@ def compare_config():
 
             self.eventuallyEqual(lambda: self.query_database(leader.metadata.name, "postgres", get_slot_query%("database", slot_to_change))[0], "bar",
                 "The replication slot cannot be updated", 10, 5)
-            
+
             # make sure slot from Patroni didn't get deleted
             self.eventuallyEqual(lambda: len(self.query_database(leader.metadata.name, "postgres", get_slot_query%("slot_name", patroni_slot))), 1,
                 "The replication slot from Patroni gets deleted", 10, 5)
@@ -932,7 +932,7 @@ def test_ignored_annotations(self):
                     },
                 }
             }
-            
+
             old_sts_creation_timestamp = sts.metadata.creation_timestamp
             k8s.api.apps_v1.patch_namespaced_stateful_set(sts.metadata.name, sts.metadata.namespace, annotation_patch)
             old_svc_creation_timestamp = svc.metadata.creation_timestamp
@@ -1369,7 +1369,7 @@ def test_persistent_volume_claim_retention_policy(self):
         }
         k8s.update_config(patch_scaled_policy_retain)
         self.eventuallyEqual(lambda: k8s.get_operator_state(), {"0": "idle"}, "Operator does not get in sync")
- 
+
         # decrease the number of instances
         k8s.api.custom_objects_api.patch_namespaced_custom_object(
             'acid.zalan.do', 'v1', 'default', 'postgresqls', 'acid-minimal-cluster', pg_patch_scale_down_instances)
@@ -1646,7 +1646,6 @@ def test_node_readiness_label(self):
         # 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'
@@ -1799,7 +1798,7 @@ def test_password_rotation(self):
             },
         }
         k8s.api.core_v1.patch_namespaced_secret(
-            name="foo-user.acid-minimal-cluster.credentials.postgresql.acid.zalan.do", 
+            name="foo-user.acid-minimal-cluster.credentials.postgresql.acid.zalan.do",
             namespace="default",
             body=secret_fake_rotation)
 
@@ -1816,7 +1815,7 @@ def test_password_rotation(self):
                 "enable_password_rotation": "true",
                 "inherited_annotations": "environment",
                 "password_rotation_interval": "30",
-                "password_rotation_user_retention": "30",  # should be set to 60 
+                "password_rotation_user_retention": "30",  # should be set to 60
             },
         }
         k8s.update_config(enable_password_rotation)
@@ -1885,7 +1884,7 @@ def test_password_rotation(self):
         self.assertTrue("environment" in db_user_secret.metadata.annotations, "Added annotation was not propagated to secret")
 
         # disable password rotation for all other users (foo_user)
-        # and pick smaller intervals to see if the third fake rotation user is dropped 
+        # and pick smaller intervals to see if the third fake rotation user is dropped
         enable_password_rotation = {
             "data": {
                 "enable_password_rotation": "false",
@@ -2385,6 +2384,56 @@ def test_taint_based_eviction(self):
         # 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 @@ def test_zz_cluster_deletion(self):
             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()))
@@ -2502,7 +2551,7 @@ def assert_distributed_pods(self, target_nodes, cluster_labels='cluster-name=aci
 
         # if nodes are different we can quit here
         if master_nodes[0] not in replica_nodes:
-            return True             
+            return True
 
         # enable pod anti affintiy in config map which should trigger movement of replica
         patch_enable_antiaffinity = {
@@ -2526,7 +2575,7 @@ def assert_distributed_pods(self, target_nodes, cluster_labels='cluster-name=aci
             }
             k8s.update_config(patch_disable_antiaffinity, "disable antiaffinity")
             self.eventuallyEqual(lambda: k8s.get_operator_state(), {"0": "idle"}, "Operator does not get in sync")
-            
+
             k8s.wait_for_pod_start('spilo-role=replica,' + cluster_labels)
             k8s.wait_for_running_pods(cluster_labels, 2)
 
@@ -2537,7 +2586,7 @@ def assert_distributed_pods(self, target_nodes, cluster_labels='cluster-name=aci
             # if nodes are different we can quit here
             for target_node in target_nodes:
                 if (target_node not in master_nodes or target_node not in replica_nodes) and master_nodes[0] in replica_nodes:
-                    print('Pods run on the same node') 
+                    print('Pods run on the same node')
                     return False
 
         except timeout_decorator.TimeoutError:

manifests/postgresql.crd.yaml

@@ -582,6 +582,22 @@ spec:
                         - PreferNoSchedule
                     tolerationSeconds:
                       type: integer
+              topologySpreadConstraints:
+                type: array
+                nullable: true
+                items:
+                  type: object
+                  properties:
+                    maxSkew:
+                      type: integer
+                      format: int32
+                    topologyKey:
+                      type: string
+                    whenUnsatisfiable:
+                      type: string
+                      enum:
+                        - DoNotSchedule
+                        - ScheduleAnyway
               useLoadBalancer:
                 type: boolean
                 description: deprecated

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

@@ -111,6 +111,7 @@ var OperatorConfigCRDResourceColumns = []apiextv1.CustomResourceColumnDefinition
 
 var min0 = 0.0
 var min1 = 1.0
+var minLength1 int64 = 1
 var minDisable = -1.0
 
 // PostgresCRDResourceValidation to check applied manifest parameters
@@ -895,6 +896,34 @@ var PostgresCRDResourceValidation = apiextv1.CustomResourceValidation{
 							},
 						},
 					},
+					"topologySpreadConstraints": {
+						Type:     "array",
+						Nullable: true,
+						Items: &apiextv1.JSONSchemaPropsOrArray{
+							Schema: &apiextv1.JSONSchemaProps{
+								Type: "object",
+								Properties: map[string]apiextv1.JSONSchemaProps{
+									"maxSkew": {
+										Type:    "integer",
+										Format:  "int32",
+										Minimum: &min1,
+									},
+									"topologyKey": {
+										Type:      "string",
+										MinLength: &minLength1,
+									},
+									"whenUnsatisfiable": {
+										Type: "string",
+										Enum: []apiextv1.JSON{
+											{Raw: []byte(`"DoNotSchedule"`)},
+											{Raw: []byte(`"ScheduleAnyway"`)},
+										},
+									},
+								},
+								Required: []string{"maxSkew", "topologyKey", "whenUnsatisfiable"},
+							},
+						},
+					},
 					"useLoadBalancer": {
 						Type:        "boolean",
 						Description: "deprecated",

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

@@ -63,24 +63,25 @@ type PostgresSpec struct {
 	UsersWithSecretRotation        []string             `json:"usersWithSecretRotation,omitempty"`
 	UsersWithInPlaceSecretRotation []string             `json:"usersWithInPlaceSecretRotation,omitempty"`
 
-	NumberOfInstances      int32                       `json:"numberOfInstances"`
-	MaintenanceWindows     []MaintenanceWindow         `json:"maintenanceWindows,omitempty"`
-	Clone                  *CloneDescription           `json:"clone,omitempty"`
-	Databases              map[string]string           `json:"databases,omitempty"`
-	PreparedDatabases      map[string]PreparedDatabase `json:"preparedDatabases,omitempty"`
-	SchedulerName          *string                     `json:"schedulerName,omitempty"`
-	NodeAffinity           *v1.NodeAffinity            `json:"nodeAffinity,omitempty"`
-	Tolerations            []v1.Toleration             `json:"tolerations,omitempty"`
-	Sidecars               []Sidecar                   `json:"sidecars,omitempty"`
-	InitContainers         []v1.Container              `json:"initContainers,omitempty"`
-	PodPriorityClassName   string                      `json:"podPriorityClassName,omitempty"`
-	ShmVolume              *bool                       `json:"enableShmVolume,omitempty"`
-	EnableLogicalBackup    bool                        `json:"enableLogicalBackup,omitempty"`
-	LogicalBackupRetention string                      `json:"logicalBackupRetention,omitempty"`
-	LogicalBackupSchedule  string                      `json:"logicalBackupSchedule,omitempty"`
-	StandbyCluster         *StandbyDescription         `json:"standby,omitempty"`
-	PodAnnotations         map[string]string           `json:"podAnnotations,omitempty"`
-	ServiceAnnotations     map[string]string           `json:"serviceAnnotations,omitempty"`
+	NumberOfInstances         int32                         `json:"numberOfInstances"`
+	MaintenanceWindows        []MaintenanceWindow           `json:"maintenanceWindows,omitempty"`
+	Clone                     *CloneDescription             `json:"clone,omitempty"`
+	Databases                 map[string]string             `json:"databases,omitempty"`
+	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"`
+	PodPriorityClassName      string                        `json:"podPriorityClassName,omitempty"`
+	ShmVolume                 *bool                         `json:"enableShmVolume,omitempty"`
+	EnableLogicalBackup       bool                          `json:"enableLogicalBackup,omitempty"`
+	LogicalBackupRetention    string                        `json:"logicalBackupRetention,omitempty"`
+	LogicalBackupSchedule     string                        `json:"logicalBackupSchedule,omitempty"`
+	StandbyCluster            *StandbyDescription           `json:"standby,omitempty"`
+	PodAnnotations            map[string]string             `json:"podAnnotations,omitempty"`
+	ServiceAnnotations        map[string]string             `json:"serviceAnnotations,omitempty"`
 	// MasterServiceAnnotations takes precedence over ServiceAnnotations for master role if not empty
 	MasterServiceAnnotations map[string]string `json:"masterServiceAnnotations,omitempty"`
 	// ReplicaServiceAnnotations takes precedence over ServiceAnnotations for replica role if not empty

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)
 	}
@@ -1466,6 +1478,7 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 		initContainers,
 		sidecarContainers,
 		c.OpConfig.SharePgSocketWithSidecars,
+		spec.TopologySpreadConstraints,
 		&tolerationSpec,
 		effectiveRunAsUser,
 		effectiveRunAsGroup,
@@ -2344,6 +2357,8 @@ func (c *Cluster) generateLogicalBackupJob() (*batchv1.CronJob, error) {
 
 	tolerationsSpec := tolerations(&spec.Tolerations, c.OpConfig.PodToleration)
 
+	topologySpreadConstraintsSpec := generateTopologySpreadConstraints(labels, spec.TopologySpreadConstraints)
+
 	// re-use the method that generates DB pod templates
 	if podTemplate, err = c.generatePodTemplate(
 		c.Namespace,
@@ -2353,6 +2368,7 @@ func (c *Cluster) generateLogicalBackupJob() (*batchv1.CronJob, error) {
 		[]v1.Container{},
 		[]v1.Container{},
 		util.False(),
+		topologySpreadConstraintsSpec,
 		&tolerationsSpec,
 		nil,
 		nil,