[pull] master from gardener:master

pkg/gardenlet/operation/botanist/etcd.go

@@ -43,7 +43,12 @@ func (b *Botanist) DefaultEtcd(role string, class etcd.Class) (etcd.Interface, e
 
 	// Prefix etcd member names with the seed name so that members can be distinguished across
 	// control plane migrations between seeds. Self-hosted shoots have no Seed object.
-	if !b.Shoot.IsSelfHosted() {
+	// spec.memberNamePrefix requires etcd-druid v0.37+, only available when UpgradeEtcdVersion is enabled.
+	//
+	// TODO(acumino): Remove this `UpgradeEtcdVersion` feature gate check once the feature gate is permanently enabled and the feature gate is removed.
+	// TODO(acumino): Rework this feature gate condition once `UpgradeEtcdVersion` is enabled by default.
+	if !b.Shoot.IsSelfHosted() &&
+		b.Config != nil && b.Config.ETCDConfig != nil && b.Config.ETCDConfig.FeatureGates["UpgradeEtcdVersion"] {
 		values.MemberNamePrefix = b.Seed.GetInfo().Name
 	}
 

pkg/gardenlet/operation/botanist/etcd_test.go

@@ -87,6 +87,11 @@ var _ = Describe("Etcd", func() {
 			botanist.Shoot = &shootpkg.Shoot{
 				ControlPlaneNamespace: namespace,
 			}
+			botanist.Config = &gardenletconfigv1alpha1.GardenletConfiguration{
+				ETCDConfig: &gardenletconfigv1alpha1.ETCDConfig{
+					FeatureGates: map[string]bool{"UpgradeEtcdVersion": true},
+				},
+			}
 			botanist.Seed.SetInfo(&gardencorev1beta1.Seed{ObjectMeta: metav1.ObjectMeta{Name: "test-seed"}})
 			botanist.Shoot.SetInfo(&gardencorev1beta1.Shoot{
 				Spec: gardencorev1beta1.ShootSpec{
@@ -226,6 +231,40 @@ var _ = Describe("Etcd", func() {
 			})
 		})
 
+		Context("UpgradeEtcdVersion feature gate disabled", func() {
+			BeforeEach(func() {
+				botanist.Config.ETCDConfig.FeatureGates["UpgradeEtcdVersion"] = false
+				validator.expectedMemberNamePrefix = Equal("")
+			})
+
+			It("should not set MemberNamePrefix when UpgradeEtcdVersion is disabled", func() {
+				oldNewEtcd := NewEtcd
+				defer func() { NewEtcd = oldNewEtcd }()
+				NewEtcd = validator.NewEtcd
+
+				etcd, err := botanist.DefaultEtcd(role, class)
+				Expect(etcd).NotTo(BeNil())
+				Expect(err).NotTo(HaveOccurred())
+			})
+		})
+
+		Context("UpgradeEtcdVersion feature gate not specified", func() {
+			BeforeEach(func() {
+				botanist.Config.ETCDConfig.FeatureGates = nil
+				validator.expectedMemberNamePrefix = Equal("")
+			})
+
+			It("should not set MemberNamePrefix when FeatureGates is nil", func() {
+				oldNewEtcd := NewEtcd
+				defer func() { NewEtcd = oldNewEtcd }()
+				NewEtcd = validator.NewEtcd
+
+				etcd, err := botanist.DefaultEtcd(role, class)
+				Expect(etcd).NotTo(BeNil())
+				Expect(err).NotTo(HaveOccurred())
+			})
+		})
+
 		It("should return an error because the maintenance time window cannot be parsed", func() {
 			botanist.Shoot.GetInfo().Spec.Maintenance.TimeWindow = &gardencorev1beta1.MaintenanceTimeWindow{
 				Begin: "foobar",