feat(pooler): support priorityClassName for connection pooler pods

charts/postgres-operator/crds/operatorconfigurations.yaml

@@ -119,6 +119,8 @@ spec:
                     format: int32
                     minimum: 1
                     type: integer
+                  connection_pooler_priority_class_name:
+                    type: string
                   connection_pooler_schema:
                     default: pooler
                     type: string

charts/postgres-operator/crds/postgresqls.yaml

@@ -168,6 +168,8 @@ spec:
                     format: int32
                     minimum: 1
                     type: integer
+                  priorityClassName:
+                    type: string
                   resources:
                     description: Resources describes requests and limits for the cluster
                       resouces.

charts/postgres-operator/values.yaml

@@ -474,6 +474,8 @@ configConnectionPooler:
   connection_pooler_mode: "transaction"
   # number of pooler instances
   connection_pooler_number_of_instances: 2
+  # priorityClassName to assign to pooler pods
+  # connection_pooler_priority_class_name: ""
   # default resources
   connection_pooler_default_cpu_request: 500m
   connection_pooler_default_memory_request: 100Mi

docs/reference/cluster_manifest.md

@@ -656,6 +656,14 @@ for both master and replica pooler services (if `enableReplicaConnectionPooler`
 * **mode**
   In which mode to run connection pooler, transaction or session.
 
+* **priorityClassName**
+  a name of the [priority
+  class](https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/#priorityclass)
+  that should be assigned to the connection pooler pods. When not specified, the
+  value is taken from the `connection_pooler_priority_class_name` operator
+  parameter, if not set then the default priority class is taken. The priority
+  class itself must be defined in advance. Optional.
+
 * **resources**
   Resource configuration for connection pooler deployment.
 

docs/reference/operator_parameters.md

@@ -1100,6 +1100,12 @@ operator being able to provide some reasonable defaults.
 * **connection_pooler_mode**
   Default pooler mode, `session` or `transaction`. Default is `transaction`.
 
+* **connection_pooler_priority_class_name**
+  The name of the priority class to assign to connection pooler pods by default.
+  A cluster can override this with `connectionPooler.priorityClassName`. When
+  unset, the pooler pods use no priority class. The empty string signifies no
+  assignment.
+
 * **connection_pooler_default_cpu_request**
   **connection_pooler_default_memory_reques**
   **connection_pooler_default_cpu_limit**

manifests/configmap.yaml

@@ -21,6 +21,7 @@ data:
   connection_pooler_max_db_connections: "60"
   connection_pooler_mode: "transaction"
   connection_pooler_number_of_instances: "2"
+  # connection_pooler_priority_class_name: ""
   connection_pooler_schema: "pooler"
   connection_pooler_user: "pooler"
   crd_categories: "all"

manifests/operatorconfiguration.crd.yaml

@@ -119,6 +119,8 @@ spec:
                     format: int32
                     minimum: 1
                     type: integer
+                  connection_pooler_priority_class_name:
+                    type: string
                   connection_pooler_schema:
                     default: pooler
                     type: string

manifests/postgresql-operator-default-configuration.yaml

@@ -233,6 +233,7 @@ configuration:
     # connection_pooler_max_db_connections: 60
     connection_pooler_mode: "transaction"
     connection_pooler_number_of_instances: 2
+    # connection_pooler_priority_class_name: ""
     # connection_pooler_schema: "pooler"
     # connection_pooler_user: "pooler"
   patroni:

manifests/postgresql.crd.yaml

@@ -168,6 +168,8 @@ spec:
                     format: int32
                     minimum: 1
                     type: integer
+                  priorityClassName:
+                    type: string
                   resources:
                     description: Resources describes requests and limits for the cluster
                       resouces.

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

@@ -347,6 +347,7 @@ type ConnectionPoolerConfiguration struct {
 	DefaultCPULimit string `json:"connection_pooler_default_cpu_limit,omitempty"`
 	// +kubebuilder:validation:Pattern=`^(\d+(e\d+)?|\d+(\.\d+)?(e\d+)?[EPTGMK]i?)$`
 	DefaultMemoryLimit string `json:"connection_pooler_default_memory_limit,omitempty"`
+	PriorityClassName  string `json:"connection_pooler_priority_class_name,omitempty"`
 }
 
 // OperatorLogicalBackupConfiguration defines configuration for logical backup

pkg/apis/acid.zalan.do/v1/operatorconfiguration.crd.yaml

@@ -119,6 +119,8 @@ spec:
                     format: int32
                     minimum: 1
                     type: integer
+                  connection_pooler_priority_class_name:
+                    type: string
                   connection_pooler_schema:
                     default: pooler
                     type: string

pkg/apis/acid.zalan.do/v1/postgresql.crd.yaml

@@ -168,6 +168,8 @@ spec:
                     format: int32
                     minimum: 1
                     type: integer
+                  priorityClassName:
+                    type: string
                   resources:
                     description: Resources describes requests and limits for the cluster
                       resouces.

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

@@ -325,9 +325,10 @@ type ConnectionPooler struct {
 	Schema            string `json:"schema,omitempty"`
 	User              string `json:"user,omitempty"`
 	// +kubebuilder:validation:Enum=session;transaction
-	Mode             string `json:"mode,omitempty"`
-	DockerImage      string `json:"dockerImage,omitempty"`
-	MaxDBConnections *int32 `json:"maxDBConnections,omitempty"`
+	Mode              string `json:"mode,omitempty"`
+	DockerImage       string `json:"dockerImage,omitempty"`
+	MaxDBConnections  *int32 `json:"maxDBConnections,omitempty"`
+	PriorityClassName string `json:"priorityClassName,omitempty"`
 
 	*Resources `json:"resources,omitempty"`
 }

pkg/cluster/connection_pooler.go

@@ -471,6 +471,9 @@ func (c *Cluster) generateConnectionPoolerPodTemplate(role PostgresRole) (
 			Volumes:                       poolerVolumes,
 			SecurityContext:               &securityContext,
 			ServiceAccountName:            c.OpConfig.PodServiceAccountName,
+			PriorityClassName: util.Coalesce(
+				connectionPoolerSpec.PriorityClassName,
+				c.OpConfig.ConnectionPooler.PriorityClassName),
 		},
 	}
 
@@ -893,6 +896,16 @@ func (c *Cluster) needSyncConnectionPoolerDefaults(Config *Config, spec *acidv1.
 		reasons = append(reasons, msg)
 	}
 
+	if spec.PriorityClassName == "" {
+		expectedPriorityClassName := config.PriorityClassName
+		if podTemplate.Spec.PriorityClassName != expectedPriorityClassName {
+			sync = true
+			msg := fmt.Sprintf("priorityClassName is different (having %s, required %s)",
+				podTemplate.Spec.PriorityClassName, expectedPriorityClassName)
+			reasons = append(reasons, msg)
+		}
+	}
+
 	expectedResources, err := c.generateResourceRequirements(spec.Resources,
 		makeDefaultConnectionPoolerResources(&Config.OpConfig),
 		connectionPoolerContainer)

pkg/cluster/connection_pooler_test.go

@@ -871,6 +871,72 @@ func TestConnectionPoolerDeploymentSpec(t *testing.T) {
 	}
 }
 
+func TestConnectionPoolerPriorityClassName(t *testing.T) {
+	newCluster := func(specPooler, opPooler, specPod, opPod string) *Cluster {
+		c := New(
+			Config{
+				OpConfig: config.Config{
+					Resources: config.Resources{
+						PodPriorityClassName: opPod,
+					},
+					ConnectionPooler: config.ConnectionPooler{
+						PriorityClassName: opPooler,
+					},
+				},
+			}, k8sutil.KubernetesClient{}, acidv1.Postgresql{}, logger, eventRecorder)
+		c.Spec = acidv1.PostgresSpec{
+			PodPriorityClassName: specPod,
+			ConnectionPooler:     &acidv1.ConnectionPooler{PriorityClassName: specPooler},
+		}
+		return c
+	}
+
+	tests := []struct {
+		subTest  string
+		cluster  *Cluster
+		expected string
+	}{
+		{
+			subTest:  "pooler spec wins over everything",
+			cluster:  newCluster("pooler-spec", "pooler-op", "pod-spec", "pod-op"),
+			expected: "pooler-spec",
+		},
+		{
+			subTest:  "pooler operator default when spec empty",
+			cluster:  newCluster("", "pooler-op", "pod-spec", "pod-op"),
+			expected: "pooler-op",
+		},
+		{
+			subTest:  "does not inherit cluster pod priority class",
+			cluster:  newCluster("", "", "pod-spec", "pod-op"),
+			expected: "",
+		},
+		{
+			subTest:  "does not inherit operator pod priority class",
+			cluster:  newCluster("", "", "", "pod-op"),
+			expected: "",
+		},
+		{
+			subTest:  "empty when nothing set",
+			cluster:  newCluster("", "", "", ""),
+			expected: "",
+		},
+	}
+
+	for _, role := range [2]PostgresRole{Master, Replica} {
+		for _, tt := range tests {
+			podSpec, err := tt.cluster.generateConnectionPoolerPodTemplate(role)
+			if err != nil {
+				t.Fatalf("%s [%s]: unexpected error %v", role, tt.subTest, err)
+			}
+			if podSpec.Spec.PriorityClassName != tt.expected {
+				t.Errorf("%s [%s]: got priorityClassName %q, expected %q",
+					role, tt.subTest, podSpec.Spec.PriorityClassName, tt.expected)
+			}
+		}
+	}
+}
+
 func testServiceAccount(cluster *Cluster, podSpec *v1.PodTemplateSpec, role PostgresRole) error {
 	poolerServiceAccount := podSpec.Spec.ServiceAccountName
 

pkg/controller/operator_config.go

@@ -282,6 +282,7 @@ func (c *Controller) importConfigurationFromCRD(fromCRD *acidv1.OperatorConfigur
 	result.ConnectionPooler.ConnectionPoolerDefaultMemoryRequest = fromCRD.ConnectionPooler.DefaultMemoryRequest
 	result.ConnectionPooler.ConnectionPoolerDefaultCPULimit = fromCRD.ConnectionPooler.DefaultCPULimit
 	result.ConnectionPooler.ConnectionPoolerDefaultMemoryLimit = fromCRD.ConnectionPooler.DefaultMemoryLimit
+	result.ConnectionPooler.PriorityClassName = fromCRD.ConnectionPooler.PriorityClassName
 
 	result.ConnectionPooler.MaxDBConnections = util.CoalesceInt32(
 		fromCRD.ConnectionPooler.MaxDBConnections,

pkg/util/config/config.go

@@ -161,6 +161,7 @@ type ConnectionPooler struct {
 	Image                                string `name:"connection_pooler_image" default:"ghcr.io/zalando/postgres-operator/pgbouncer:latest"`
 	Mode                                 string `name:"connection_pooler_mode" default:"transaction"`
 	MaxDBConnections                     *int32 `name:"connection_pooler_max_db_connections" default:"60"`
+	PriorityClassName                    string `name:"connection_pooler_priority_class_name"`
 	ConnectionPoolerDefaultCPURequest    string `name:"connection_pooler_default_cpu_request"`
 	ConnectionPoolerDefaultMemoryRequest string `name:"connection_pooler_default_memory_request"`
 	ConnectionPoolerDefaultCPULimit      string `name:"connection_pooler_default_cpu_limit"`