Add support for ephemeral PostgresQL instances

charts/postgres-operator/crds/operatorconfigurations.yaml

@@ -692,6 +692,9 @@ spec:
                   enable_patroni_failsafe_mode:
                     type: boolean
                     default: false
+              allow_ephemeral_volumes:
+                type: boolean
+                default: false
           status:
             type: object
             additionalProperties:

charts/postgres-operator/crds/postgresqls.yaml

@@ -577,6 +577,9 @@ spec:
                         - PreferNoSchedule
                     tolerationSeconds:
                       type: integer
+              useEphemeralVolume:
+                type: boolean
+                default: false
               useLoadBalancer:
                 type: boolean
                 description: deprecated

charts/postgres-operator/templates/operatorconfiguration.yaml

@@ -42,4 +42,5 @@ configuration:
 {{ tpl (toYaml .Values.configConnectionPooler) . | indent 4 }}
   patroni:
 {{ tpl (toYaml .Values.configPatroni) . | indent 4 }}
+  allow_ephemeral_volumes: {{ .Values.allowEphemeralVolumes }}
 {{- end }}

charts/postgres-operator/values.yaml

@@ -454,6 +454,9 @@ configPatroni:
 # Zalando's internal CDC stream feature
 enableStreams: false
 
+# Allow ephemeral instances
+allowEphemeralVolumes: false
+
 rbac:
   # Specifies whether RBAC resources should be created
   create: true

manifests/configmap.yaml

@@ -7,6 +7,7 @@ data:
   # additional_pod_capabilities: "SYS_NICE"
   # additional_secret_mount: "some-secret-name"
   # additional_secret_mount_path: "/some/dir"
+  # allow_ephemeral_volumes: true
   api_port: "8080"
   aws_region: eu-central-1
   cluster_domain: cluster.local

manifests/operatorconfiguration.crd.yaml

@@ -690,6 +690,9 @@ spec:
                   enable_patroni_failsafe_mode:
                     type: boolean
                     default: false
+              allow_ephemeral_volumes:
+                type: boolean
+                default: false
           status:
             type: object
             additionalProperties:

manifests/postgresql-operator-default-configuration.yaml

@@ -220,3 +220,4 @@ configuration:
     # connection_pooler_user: "pooler"
   patroni:
     enable_patroni_failsafe_mode: false
+  allow_ephemeral_volumes: false

manifests/postgresql.crd.yaml

@@ -575,6 +575,9 @@ spec:
                         - PreferNoSchedule
                     tolerationSeconds:
                       type: integer
+              useEphemeralVolume:
+                type: boolean
+                default: false
               useLoadBalancer:
                 type: boolean
                 description: deprecated

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

@@ -898,6 +898,9 @@ var PostgresCRDResourceValidation = apiextv1.CustomResourceValidation{
 							},
 						},
 					},
+					"useEphemeralVolume": {
+						Type: "boolean",
+					},
 					"useLoadBalancer": {
 						Type:        "boolean",
 						Description: "deprecated",
@@ -1966,6 +1969,9 @@ var OperatorConfigCRDResourceValidation = apiextv1.CustomResourceValidation{
 							},
 						},
 					},
+					"allow_ephemeral_volums": {
+						Type: "boolean",
+					},
 				},
 			},
 			"status": {

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

@@ -287,6 +287,8 @@ type OperatorConfigurationData struct {
 	MinInstances                      int32  `json:"min_instances,omitempty"`
 	MaxInstances                      int32  `json:"max_instances,omitempty"`
 	IgnoreInstanceLimitsAnnotationKey string `json:"ignore_instance_limits_annotation_key,omitempty"`
+
+	AllowEphemeralVolumes *bool `json:"allow_ephemeral_volumes,omitempty"`
 }
 
 // Duration shortens this frequently used name

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

@@ -93,6 +93,9 @@ type PostgresSpec struct {
 	// deprecated json tags
 	InitContainersOld       []v1.Container `json:"init_containers,omitempty"`
 	PodPriorityClassNameOld string         `json:"pod_priority_class_name,omitempty"`
+
+	// Ephemeral settings
+	UseEphemeralVolume *bool `json:"useEphemeralVolume,omitempty"`
 }
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

pkg/cluster/k8sres.go

@@ -1289,10 +1289,12 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 		initContainers      []v1.Container
 		sidecarContainers   []v1.Container
 		podTemplate         *v1.PodTemplateSpec
-		volumeClaimTemplate *v1.PersistentVolumeClaim
+		volumeClaimTemplate *[]v1.PersistentVolumeClaim
 		additionalVolumes   = spec.AdditionalVolumes
 	)
 
+	useEphemeralVolume := c.OpConfig.AllowEphemeralVolumes != nil && spec.UseEphemeralVolume != nil && (*c.OpConfig.AllowEphemeralVolumes && *spec.UseEphemeralVolume)
+
 	defaultResources := makeDefaultResources(&c.OpConfig)
 	resourceRequirements, err := c.generateResourceRequirements(
 		spec.Resources, defaultResources, constants.PostgresContainerName)
@@ -1493,9 +1495,23 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 		return nil, fmt.Errorf("could not generate pod template: %v", err)
 	}
 
-	if volumeClaimTemplate, err = c.generatePersistentVolumeClaimTemplate(spec.Volume.Size,
-		spec.Volume.StorageClass, spec.Volume.Selector); err != nil {
-		return nil, fmt.Errorf("could not generate volume claim template: %v", err)
+	// Generate the volumes, optionally using an ephemeral volume
+	if useEphemeralVolume {
+		empty := make([]v1.PersistentVolumeClaim, 0)
+		volumeClaimTemplate = &empty
+
+		// Also add the ephemeral volume to the spec
+		podTemplate.Spec.Volumes = append(podTemplate.Spec.Volumes, v1.Volume{
+			Name: constants.DataVolumeName,
+			VolumeSource: v1.VolumeSource{
+				EmptyDir: &v1.EmptyDirVolumeSource{},
+			},
+		})
+	} else {
+		if volumeClaimTemplate, err = c.generatePersistentVolumeClaimTemplate(spec.Volume.Size,
+			spec.Volume.StorageClass, spec.Volume.Selector); err != nil {
+			return nil, fmt.Errorf("could not generate volume claim template: %v", err)
+		}
 	}
 
 	// global minInstances and maxInstances settings can overwrite manifest
@@ -1540,7 +1556,7 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 			Selector:                             c.labelsSelector(),
 			ServiceName:                          c.serviceName(Master),
 			Template:                             *podTemplate,
-			VolumeClaimTemplates:                 []v1.PersistentVolumeClaim{*volumeClaimTemplate},
+			VolumeClaimTemplates:                 *volumeClaimTemplate,
 			UpdateStrategy:                       updateStrategy,
 			PodManagementPolicy:                  podManagementPolicy,
 			PersistentVolumeClaimRetentionPolicy: &persistentVolumeClaimRetentionPolicy,
@@ -1848,7 +1864,7 @@ func (c *Cluster) addAdditionalVolumes(podSpec *v1.PodSpec,
 }
 
 func (c *Cluster) generatePersistentVolumeClaimTemplate(volumeSize, volumeStorageClass string,
-	volumeSelector *metav1.LabelSelector) (*v1.PersistentVolumeClaim, error) {
+	volumeSelector *metav1.LabelSelector) (*[]v1.PersistentVolumeClaim, error) {
 
 	var storageClassName *string
 	if volumeStorageClass != "" {
@@ -1861,7 +1877,7 @@ func (c *Cluster) generatePersistentVolumeClaimTemplate(volumeSize, volumeStorag
 	}
 
 	volumeMode := v1.PersistentVolumeFilesystem
-	volumeClaim := &v1.PersistentVolumeClaim{
+	volumeClaim := v1.PersistentVolumeClaim{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:        constants.DataVolumeName,
 			Annotations: c.annotationsSet(nil),
@@ -1880,7 +1896,7 @@ func (c *Cluster) generatePersistentVolumeClaimTemplate(volumeSize, volumeStorag
 		},
 	}
 
-	return volumeClaim, nil
+	return &[]v1.PersistentVolumeClaim{volumeClaim}, nil
 }
 
 func (c *Cluster) generateUserSecrets() map[string]*v1.Secret {

pkg/controller/operator_config.go

@@ -277,5 +277,8 @@ func (c *Controller) importConfigurationFromCRD(fromCRD *acidv1.OperatorConfigur
 		fromCRD.ConnectionPooler.MaxDBConnections,
 		k8sutil.Int32ToPointer(constants.ConnectionPoolerMaxDBConnections))
 
+	// Ephemeral config
+	result.AllowEphemeralVolumes = util.CoalesceBool(fromCRD.AllowEphemeralVolumes, util.False())
+
 	return result
 }

pkg/util/config/config.go

@@ -253,6 +253,7 @@ type Config struct {
 	EnableSecretsDeletion                    *bool             `name:"enable_secrets_deletion" default:"true"`
 	EnablePersistentVolumeClaimDeletion      *bool             `name:"enable_persistent_volume_claim_deletion" default:"true"`
 	PersistentVolumeClaimRetentionPolicy     map[string]string `name:"persistent_volume_claim_retention_policy" default:"when_deleted:retain,when_scaled:retain"`
+	AllowEphemeralVolumes                    *bool             `json:"allow_ephemeral_volumes,omitempty"`
 }
 
 // MustMarshal marshals the config or panics