statefulset PersistentVolumeClaimDeletePolicy api change

pkg/apis/apps/fuzzer/fuzzer.go

@@ -40,6 +40,17 @@ var Funcs = func(codecs runtimeserializer.CodecFactory) []interface{} {
 			if len(s.Spec.UpdateStrategy.Type) == 0 {
 				s.Spec.UpdateStrategy.Type = apps.RollingUpdateStatefulSetStrategyType
 			}
+			if s.Spec.PersistentVolumeClaimRetentionPolicy == nil {
+				policies := []apps.PersistentVolumeClaimRetentionPolicyType{
+					apps.RetainPersistentVolumeClaimRetentionPolicyType,
+					apps.DeletePersistentVolumeClaimRetentionPolicyType,
+				}
+				choice := int32(c.Rand.Int31())
+				s.Spec.PersistentVolumeClaimRetentionPolicy = &apps.StatefulSetPersistentVolumeClaimRetentionPolicy{
+					WhenDeleted: policies[choice&1],
+					WhenScaled:  policies[(choice>>1)&1],
+				}
+			}
 			if s.Spec.RevisionHistoryLimit == nil {
 				s.Spec.RevisionHistoryLimit = new(int32)
 				*s.Spec.RevisionHistoryLimit = 10

pkg/apis/apps/types.go

@@ -97,6 +97,40 @@ type RollingUpdateStatefulSetStrategy struct {
 	Partition int32
 }
 
+// PersistentVolumeClaimRetentionPolicyType is a string enumeration of the policies that will determine
+// when volumes from the VolumeClaimTemplates will be deleted when the controlling StatefulSet is
+// deleted or scaled down.
+type PersistentVolumeClaimRetentionPolicyType string
+
+const (
+	// RetainPersistentVolumeClaimRetentionPolicyType is the default
+	// PersistentVolumeClaimRetentionPolicy and specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will not be deleted.
+	RetainPersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Retain"
+	// DeletePersistentVolumeClaimRetentionPolicyType specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will be deleted in the scenario specified in
+	// StatefulSetPersistentVolumeClaimPolicy.
+	DeletePersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Delete"
+)
+
+// StatefulSetPersistentVolumeClaimRetentionPolicy describes the policy used for PVCs
+// created from the StatefulSet VolumeClaimTemplates.
+type StatefulSetPersistentVolumeClaimRetentionPolicy struct {
+	// WhenDeleted specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is deleted. The default policy
+	// of `Retain` causes PVCs to not be affected by StatefulSet deletion. The
+	// `Delete` policy causes those PVCs to be deleted.
+	WhenDeleted PersistentVolumeClaimRetentionPolicyType
+	// WhenScaled specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is scaled down. The default
+	// policy of `Retain` causes PVCs to not be affected by a scaledown. The
+	// `Delete` policy causes the associated PVCs for any excess pods above
+	// the replica count to be deleted.
+	WhenScaled PersistentVolumeClaimRetentionPolicyType
+}
+
 // A StatefulSetSpec is the specification of a StatefulSet.
 type StatefulSetSpec struct {
 	// Replicas is the desired number of replicas of the given Template.
@@ -164,6 +198,12 @@ type StatefulSetSpec struct {
 	// This is an alpha field and requires enabling StatefulSetMinReadySeconds feature gate.
 	// +optional
 	MinReadySeconds int32
+
+	// PersistentVolumeClaimRetentionPolicy describes the policy used for PVCs created from
+	// the StatefulSet VolumeClaimTemplates. This requires the
+	// StatefulSetAutoDeletePVC feature gate to be enabled, which is alpha.
+	// +optional
+	PersistentVolumeClaimRetentionPolicy *StatefulSetPersistentVolumeClaimRetentionPolicy
 }
 
 // StatefulSetStatus represents the current state of a StatefulSet.

pkg/apis/apps/v1/defaults.go

@@ -20,6 +20,8 @@ import (
 	appsv1 "k8s.io/api/apps/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/kubernetes/pkg/features"
 )
 
 func addDefaultingFuncs(scheme *runtime.Scheme) error {
@@ -117,6 +119,18 @@ func SetDefaults_StatefulSet(obj *appsv1.StatefulSet) {
 		*obj.Spec.UpdateStrategy.RollingUpdate.Partition = 0
 	}
 
+	if utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetAutoDeletePVC) {
+		if obj.Spec.PersistentVolumeClaimRetentionPolicy == nil {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy = &appsv1.StatefulSetPersistentVolumeClaimRetentionPolicy{}
+		}
+		if len(obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenDeleted) == 0 {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenDeleted = appsv1.RetainPersistentVolumeClaimRetentionPolicyType
+		}
+		if len(obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled) == 0 {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled = appsv1.RetainPersistentVolumeClaimRetentionPolicyType
+		}
+	}
+
 	if obj.Spec.Replicas == nil {
 		obj.Spec.Replicas = new(int32)
 		*obj.Spec.Replicas = 1

pkg/apis/apps/v1beta1/defaults.go

@@ -21,6 +21,8 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/kubernetes/pkg/features"
 )
 
 func addDefaultingFuncs(scheme *runtime.Scheme) error {
@@ -46,6 +48,19 @@ func SetDefaults_StatefulSet(obj *appsv1beta1.StatefulSet) {
 			obj.Labels = labels
 		}
 	}
+
+	if utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetAutoDeletePVC) {
+		if obj.Spec.PersistentVolumeClaimRetentionPolicy == nil {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy = &appsv1beta1.StatefulSetPersistentVolumeClaimRetentionPolicy{}
+		}
+		if len(obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenDeleted) == 0 {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenDeleted = appsv1beta1.RetainPersistentVolumeClaimRetentionPolicyType
+		}
+		if len(obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled) == 0 {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled = appsv1beta1.RetainPersistentVolumeClaimRetentionPolicyType
+		}
+	}
+
 	if obj.Spec.Replicas == nil {
 		obj.Spec.Replicas = new(int32)
 		*obj.Spec.Replicas = 1

pkg/apis/apps/v1beta2/defaults.go

@@ -20,6 +20,8 @@ import (
 	appsv1beta2 "k8s.io/api/apps/v1beta2"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/kubernetes/pkg/features"
 )
 
 func addDefaultingFuncs(scheme *runtime.Scheme) error {
@@ -72,6 +74,18 @@ func SetDefaults_StatefulSet(obj *appsv1beta2.StatefulSet) {
 		*obj.Spec.UpdateStrategy.RollingUpdate.Partition = 0
 	}
 
+	if utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetAutoDeletePVC) {
+		if obj.Spec.PersistentVolumeClaimRetentionPolicy == nil {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy = &appsv1beta2.StatefulSetPersistentVolumeClaimRetentionPolicy{}
+		}
+		if len(obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenDeleted) == 0 {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenDeleted = appsv1beta2.RetainPersistentVolumeClaimRetentionPolicyType
+		}
+		if len(obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled) == 0 {
+			obj.Spec.PersistentVolumeClaimRetentionPolicy.WhenScaled = appsv1beta2.RetainPersistentVolumeClaimRetentionPolicyType
+		}
+	}
+
 	if obj.Spec.Replicas == nil {
 		obj.Spec.Replicas = new(int32)
 		*obj.Spec.Replicas = 1

pkg/apis/apps/validation/validation.go

@@ -69,6 +69,26 @@ func ValidatePodTemplateSpecForStatefulSet(template *api.PodTemplateSpec, select
 	return allErrs
 }
 
+func ValidatePersistentVolumeClaimRetentionPolicyType(policy apps.PersistentVolumeClaimRetentionPolicyType, fldPath *field.Path) field.ErrorList {
+	var allErrs field.ErrorList
+	switch policy {
+	case apps.RetainPersistentVolumeClaimRetentionPolicyType:
+	case apps.DeletePersistentVolumeClaimRetentionPolicyType:
+	default:
+		allErrs = append(allErrs, field.NotSupported(fldPath, policy, []string{string(apps.RetainPersistentVolumeClaimRetentionPolicyType), string(apps.DeletePersistentVolumeClaimRetentionPolicyType)}))
+	}
+	return allErrs
+}
+
+func ValidatePersistentVolumeClaimRetentionPolicy(policy *apps.StatefulSetPersistentVolumeClaimRetentionPolicy, fldPath *field.Path) field.ErrorList {
+	var allErrs field.ErrorList
+	if policy != nil {
+		allErrs = append(allErrs, ValidatePersistentVolumeClaimRetentionPolicyType(policy.WhenDeleted, fldPath.Child("whenDeleted"))...)
+		allErrs = append(allErrs, ValidatePersistentVolumeClaimRetentionPolicyType(policy.WhenScaled, fldPath.Child("whenScaled"))...)
+	}
+	return allErrs
+}
+
 // ValidateStatefulSetSpec tests if required fields in the StatefulSet spec are set.
 func ValidateStatefulSetSpec(spec *apps.StatefulSetSpec, fldPath *field.Path, opts apivalidation.PodValidationOptions) field.ErrorList {
 	allErrs := field.ErrorList{}
@@ -108,6 +128,8 @@ func ValidateStatefulSetSpec(spec *apps.StatefulSetSpec, fldPath *field.Path, op
 					apps.OnDeleteStatefulSetStrategyType)))
 	}
 
+	allErrs = append(allErrs, ValidatePersistentVolumeClaimRetentionPolicy(spec.PersistentVolumeClaimRetentionPolicy, fldPath.Child("persistentVolumeClaimRetentionPolicy"))...)
+
 	allErrs = append(allErrs, apivalidation.ValidateNonnegativeField(int64(spec.Replicas), fldPath.Child("replicas"))...)
 	if utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetMinReadySeconds) {
 		allErrs = append(allErrs, apivalidation.ValidateNonnegativeField(int64(spec.MinReadySeconds), fldPath.Child("minReadySeconds"))...)
@@ -152,18 +174,18 @@ func ValidateStatefulSetUpdate(statefulSet, oldStatefulSet *apps.StatefulSet) fi
 	// statefulset updates aren't super common and general updates are likely to be touching spec, so we'll do this
 	// deep copy right away.  This avoids mutating our inputs
 	newStatefulSetClone := statefulSet.DeepCopy()
-	newStatefulSetClone.Spec.Replicas = oldStatefulSet.Spec.Replicas             // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.Replicas = oldStatefulSet.Spec.Replicas                                                         // +k8s:verify-mutation:reason=clone
-	newStatefulSetClone.Spec.Template = oldStatefulSet.Spec.Template             // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.Template = oldStatefulSet.Spec.Template                                                         // +k8s:verify-mutation:reason=clone
-	newStatefulSetClone.Spec.UpdateStrategy = oldStatefulSet.Spec.UpdateStrategy // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.UpdateStrategy = oldStatefulSet.Spec.UpdateStrategy                                             // +k8s:verify-mutation:reason=clone
 	if utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetMinReadySeconds) {
 		newStatefulSetClone.Spec.MinReadySeconds = oldStatefulSet.Spec.MinReadySeconds // +k8s:verify-mutation:reason=clone
 	}
+	newStatefulSetClone.Spec.PersistentVolumeClaimRetentionPolicy = oldStatefulSet.Spec.PersistentVolumeClaimRetentionPolicy // +k8s:verify-mutation:reason=clone
 	if !apiequality.Semantic.DeepEqual(newStatefulSetClone.Spec, oldStatefulSet.Spec) {
 		if utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetMinReadySeconds) {
-			allErrs = append(allErrs, field.Forbidden(field.NewPath("spec"), "updates to statefulset spec for fields other than 'replicas', 'template', 'minReadySeconds' and 'updateStrategy' are forbidden"))
+			allErrs = append(allErrs, field.Forbidden(field.NewPath("spec"), "updates to statefulset spec for fields other than 'replicas', 'template', 'updateStrategy' and 'persistentVolumeClaimRetentionPolicy' are forbidden"))
 		} else {
-			allErrs = append(allErrs, field.Forbidden(field.NewPath("spec"), "updates to statefulset spec for fields other than 'replicas', 'template' and 'updateStrategy' are forbidden"))
+			allErrs = append(allErrs, field.Forbidden(field.NewPath("spec"), "updates to statefulset spec for fields other than 'replicas', 'template', 'updateStrategy', 'minReadySeconds' and 'persistentVolumeClaimRetentionPolicy' are forbidden"))
-		}
 	}
 
 	allErrs = append(allErrs, apivalidation.ValidateNonnegativeField(int64(statefulSet.Spec.Replicas), field.NewPath("spec", "replicas"))...)

pkg/registry/apps/statefulset/strategy.go

@@ -88,6 +88,7 @@ func (statefulSetStrategy) PrepareForCreate(ctx context.Context, obj runtime.Obj
 	statefulSet.Status = apps.StatefulSetStatus{}
 
 	statefulSet.Generation = 1
+
 	dropStatefulSetDisabledFields(statefulSet, nil)
 	pod.DropDisabledTemplateFields(&statefulSet.Spec.Template, nil)
 }
@@ -122,6 +123,12 @@ func dropStatefulSetDisabledFields(newSS *apps.StatefulSet, oldSS *apps.Stateful
 			newSS.Spec.MinReadySeconds = int32(0)
 		}
 	}
+
+	if !utilfeature.DefaultFeatureGate.Enabled(features.StatefulSetAutoDeletePVC) {
+		if oldStatefulSet == nil || oldStatefulSet.Spec.PersistentVolumeClaimRetentionPolicy == nil {
+			newStatefulSet.Spec.PersistentVolumeClaimRetentionPolicy = nil
+		}
+	}
 }
 
 // minReadySecondsFieldsInUse returns true if fields related to StatefulSet minReadySeconds are set and

staging/src/k8s.io/api/apps/v1/types.go

@@ -116,6 +116,40 @@ type RollingUpdateStatefulSetStrategy struct {
 	Partition *int32 `json:"partition,omitempty" protobuf:"varint,1,opt,name=partition"`
 }
 
+// PersistentVolumeClaimRetentionPolicyType is a string enumeration of the policies that will determine
+// when volumes from the VolumeClaimTemplates will be deleted when the controlling StatefulSet is
+// deleted or scaled down.
+type PersistentVolumeClaimRetentionPolicyType string
+
+const (
+	// RetainPersistentVolumeClaimRetentionPolicyType is the default
+	// PersistentVolumeClaimRetentionPolicy and specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will not be deleted.
+	RetainPersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Retain"
+	// RetentionPersistentVolumeClaimRetentionPolicyType specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will be deleted in the scenario specified in
+	// StatefulSetPersistentVolumeClaimRetentionPolicy.
+	DeletePersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Delete"
+)
+
+// StatefulSetPersistentVolumeClaimRetentionPolicy describes the policy used for PVCs
+// created from the StatefulSet VolumeClaimTemplates.
+type StatefulSetPersistentVolumeClaimRetentionPolicy struct {
+	// WhenDeleted specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is deleted. The default policy
+	// of `Retain` causes PVCs to not be affected by StatefulSet deletion. The
+	// `Delete` policy causes those PVCs to be deleted.
+	WhenDeleted PersistentVolumeClaimRetentionPolicyType `json:"whenDeleted,omitempty" protobuf:"bytes,1,opt,name=whenDeleted,casttype=PersistentVolumeClaimRetentionPolicyType"`
+	// WhenScaled specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is scaled down. The default
+	// policy of `Retain` causes PVCs to not be affected by a scaledown. The
+	// `Delete` policy causes the associated PVCs for any excess pods above
+	// the replica count to be deleted.
+	WhenScaled PersistentVolumeClaimRetentionPolicyType `json:"whenScaled,omitempty" protobuf:"bytes,2,opt,name=whenScaled,casttype=PersistentVolumeClaimRetentionPolicyType"`
+}
+
 // A StatefulSetSpec is the specification of a StatefulSet.
 type StatefulSetSpec struct {
 	// replicas is the desired number of replicas of the given Template.
@@ -182,6 +216,15 @@ type StatefulSetSpec struct {
 	// This is an alpha field and requires enabling StatefulSetMinReadySeconds feature gate.
 	// +optional
 	MinReadySeconds int32 `json:"minReadySeconds,omitempty" protobuf:"varint,9,opt,name=minReadySeconds"`
+
+	// persistentVolumeClaimRetentionPolicy describes the lifecycle of persistent
+	// volume claims created from volumeClaimTemplates. By default, all persistent
+	// volume claims are created as needed and retained until manually deleted. This
+	// policy allows the lifecycle to be altered, for example by deleting persistent
+	// volume claims when their stateful set is deleted, or when their pod is scaled
+	// down. This requires the StatefulSetAutoDeletePVC feature gate to be enabled,
+	// which is alpha.  +optional
+	PersistentVolumeClaimRetentionPolicy *StatefulSetPersistentVolumeClaimRetentionPolicy `json:"persistentVolumeClaimRetentionPolicy,omitempty" protobuf:"bytes,9,opt,name=persistentVolumeClaimRetentionPolicy"`
 }
 
 // StatefulSetStatus represents the current state of a StatefulSet.

staging/src/k8s.io/api/apps/v1beta1/types.go

@@ -158,6 +158,40 @@ type RollingUpdateStatefulSetStrategy struct {
 	Partition *int32 `json:"partition,omitempty" protobuf:"varint,1,opt,name=partition"`
 }
 
+// PersistentVolumeClaimRetentionPolicyType is a string enumeration of the policies that will determine
+// when volumes from the VolumeClaimTemplates will be deleted when the controlling StatefulSet is
+// deleted or scaled down.
+type PersistentVolumeClaimRetentionPolicyType string
+
+const (
+	// RetainPersistentVolumeClaimRetentionPolicyType is the default
+	// PersistentVolumeClaimRetentionPolicy and specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will not be deleted.
+	RetainPersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Retain"
+	// RetentionPersistentVolumeClaimRetentionPolicyType specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will be deleted in the scenario specified in
+	// StatefulSetPersistentVolumeClaimRetentionPolicy.
+	RetentionPersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Delete"
+)
+
+// StatefulSetPersistentVolumeClaimRetentionPolicy describes the policy used for PVCs
+// created from the StatefulSet VolumeClaimTemplates.
+type StatefulSetPersistentVolumeClaimRetentionPolicy struct {
+	// WhenDeleted specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is deleted. The default policy
+	// of `Retain` causes PVCs to not be affected by StatefulSet deletion. The
+	// `Delete` policy causes those PVCs to be deleted.
+	WhenDeleted PersistentVolumeClaimRetentionPolicyType `json:"whenDeleted,omitempty" protobuf:"bytes,1,opt,name=whenDeleted,casttype=PersistentVolumeClaimRetentionPolicyType"`
+	// WhenScaled specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is scaled down. The default
+	// policy of `Retain` causes PVCs to not be affected by a scaledown. The
+	// `Delete` policy causes the associated PVCs for any excess pods above
+	// the replica count to be deleted.
+	WhenScaled PersistentVolumeClaimRetentionPolicyType `json:"whenScaled,omitempty" protobuf:"bytes,2,opt,name=whenScaled,casttype=PersistentVolumeClaimRetentionPolicyType"`
+}
+
 // A StatefulSetSpec is the specification of a StatefulSet.
 type StatefulSetSpec struct {
 	// replicas is the desired number of replicas of the given Template.
@@ -225,6 +259,12 @@ type StatefulSetSpec struct {
 	// This is an alpha field and requires enabling StatefulSetMinReadySeconds feature gate.
 	// +optional
 	MinReadySeconds int32 `json:"minReadySeconds,omitempty" protobuf:"varint,9,opt,name=minReadySeconds"`
+
+	// PersistentVolumeClaimRetentionPolicy describes the policy used for PVCs created from
+	// the StatefulSet VolumeClaimTemplates. This requires the
+	// StatefulSetAutoDeletePVC feature gate to be enabled, which is alpha.
+	// +optional
+	PersistentVolumeClaimRetentionPolicy *StatefulSetPersistentVolumeClaimRetentionPolicy `json:"persistentVolumeClaimRetentionPolicy,omitempty" protobuf:"bytes,10,opt,name=persistentVolumeClaimRetentionPolicy"`
 }
 
 // StatefulSetStatus represents the current state of a StatefulSet.

staging/src/k8s.io/api/apps/v1beta2/types.go

@@ -169,6 +169,40 @@ type RollingUpdateStatefulSetStrategy struct {
 	Partition *int32 `json:"partition,omitempty" protobuf:"varint,1,opt,name=partition"`
 }
 
+// PersistentVolumeClaimRetentionPolicyType is a string enumeration of the policies that will determine
+// when volumes from the VolumeClaimTemplates will be deleted when the controlling StatefulSet is
+// deleted or scaled down.
+type PersistentVolumeClaimRetentionPolicyType string
+
+const (
+	// RetainPersistentVolumeClaimRetentionPolicyType is the default
+	// PersistentVolumeClaimRetentionPolicy and specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will not be deleted.
+	RetainPersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Retain"
+	// RetentionPersistentVolumeClaimRetentionPolicyType specifies that
+	// PersistentVolumeClaims associated with StatefulSet VolumeClaimTemplates
+	// will be deleted in the scenario specified in
+	// StatefulSetPersistentVolumeClaimRetentionPolicy.
+	RetentionPersistentVolumeClaimRetentionPolicyType PersistentVolumeClaimRetentionPolicyType = "Delete"
+)
+
+// StatefulSetPersistentVolumeClaimRetentionPolicy describes the policy used for PVCs
+// created from the StatefulSet VolumeClaimTemplates.
+type StatefulSetPersistentVolumeClaimRetentionPolicy struct {
+	// WhenDeleted specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is deleted. The default policy
+	// of `Retain` causes PVCs to not be affected by StatefulSet deletion. The
+	// `Delete` policy causes those PVCs to be deleted.
+	WhenDeleted PersistentVolumeClaimRetentionPolicyType `json:"whenDeleted,omitempty" protobuf:"bytes,1,opt,name=whenDeleted,casttype=PersistentVolumeClaimRetentionPolicyType"`
+	// WhenScaled specifies what happens to PVCs created from StatefulSet
+	// VolumeClaimTemplates when the StatefulSet is scaled down. The default
+	// policy of `Retain` causes PVCs to not be affected by a scaledown. The
+	// `Delete` policy causes the associated PVCs for any excess pods above
+	// the replica count to be deleted.
+	WhenScaled PersistentVolumeClaimRetentionPolicyType `json:"whenScaled,omitempty" protobuf:"bytes,2,opt,name=whenScaled,casttype=PersistentVolumeClaimRetentionPolicyType"`
+}
+
 // A StatefulSetSpec is the specification of a StatefulSet.
 type StatefulSetSpec struct {
 	// replicas is the desired number of replicas of the given Template.
@@ -235,6 +269,12 @@ type StatefulSetSpec struct {
 	// This is an alpha field and requires enabling StatefulSetMinReadySeconds feature gate.
 	// +optional
 	MinReadySeconds int32 `json:"minReadySeconds,omitempty" protobuf:"varint,9,opt,name=minReadySeconds"`
+
+	// PersistentVolumeClaimRetentionPolicy describes the policy used for PVCs created from
+	// the StatefulSet VolumeClaimTemplates. This requires the
+	// StatefulSetAutoDeletePVC feature gate to be enabled, which is alpha.
+	// +optional
+	PersistentVolumeClaimRetentionPolicy *StatefulSetPersistentVolumeClaimRetentionPolicy `json:"persistentVolumeClaimRetentionPolicy,omitempty" protobuf:"bytes,10,opt,name=persistentVolumeClaimRetentionPolicy"`
 }
 
 // StatefulSetStatus represents the current state of a StatefulSet.