Mark StatefulSet's .spec.serviceName optional

The API reference doc
(https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/stateful-set-v1/#StatefulSetSpec)
mentions .spec.serviceName field is required, because it doesn't have
optional tag, nor omitempty. In practice this field is optional, and can
be empty. This change explicitly marks the field optional.

Signed-off-by: Maciej Szulik <[email protected]>

Author: soltysh

pkg/apis/apps/types.go

@@ -198,6 +198,7 @@ type StatefulSetSpec struct {
 	// the network identity of the set. Pods get DNS/hostnames that follow the
 	// pattern: pod-specific-string.serviceName.default.svc.cluster.local
 	// where "pod-specific-string" is managed by the StatefulSet controller.
+	// +optional
 	ServiceName string
 
 	// PodManagementPolicy controls how pods are created during initial scale up,

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

@@ -220,6 +220,7 @@ type StatefulSetSpec struct {
 	// the network identity of the set. Pods get DNS/hostnames that follow the
 	// pattern: pod-specific-string.serviceName.default.svc.cluster.local
 	// where "pod-specific-string" is managed by the StatefulSet controller.
+	// +optional
 	ServiceName string `json:"serviceName" protobuf:"bytes,5,opt,name=serviceName"`
 
 	// podManagementPolicy controls how pods are created during initial scale up,

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

@@ -259,6 +259,7 @@ type StatefulSetSpec struct {
 	// the network identity of the set. Pods get DNS/hostnames that follow the
 	// pattern: pod-specific-string.serviceName.default.svc.cluster.local
 	// where "pod-specific-string" is managed by the StatefulSet controller.
+	// +optional
 	ServiceName string `json:"serviceName" protobuf:"bytes,5,opt,name=serviceName"`
 
 	// podManagementPolicy controls how pods are created during initial scale up,

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

@@ -269,6 +269,7 @@ type StatefulSetSpec struct {
 	// the network identity of the set. Pods get DNS/hostnames that follow the
 	// pattern: pod-specific-string.serviceName.default.svc.cluster.local
 	// where "pod-specific-string" is managed by the StatefulSet controller.
+	// +optional
 	ServiceName string `json:"serviceName" protobuf:"bytes,5,opt,name=serviceName"`
 
 	// podManagementPolicy controls how pods are created during initial scale up,