Implements Service Internal Traffic Policy

1. Add API definitions;
2. Add feature gate and drops the field when feature gate is not on;
3. Set default values for the field;
4. Add API Validation
5. add kube-proxy iptables and ipvs implementations
6. add tests

pkg/api/v1/service/util.go

@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"strings"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	utilnet "k8s.io/utils/net"
 )
 
@@ -76,6 +76,15 @@ func RequestsOnlyLocalTraffic(service *v1.Service) bool {
 	return service.Spec.ExternalTrafficPolicy == v1.ServiceExternalTrafficPolicyTypeLocal
 }
 
+// RequestsOnlyLocalTrafficForInternal checks if service prefers Node Local
+// endpoints for internal traffic
+func RequestsOnlyLocalTrafficForInternal(service *v1.Service) bool {
+	if service.Spec.InternalTrafficPolicy == nil {
+		return false
+	}
+	return *service.Spec.InternalTrafficPolicy == v1.ServiceInternalTrafficPolicyLocal
+}
+
 // NeedsHealthCheck checks if service needs health check.
 func NeedsHealthCheck(service *v1.Service) bool {
 	if service.Spec.Type != v1.ServiceTypeLoadBalancer {

pkg/api/v1/service/util_test.go

@@ -20,7 +20,7 @@ import (
 	"strings"
 	"testing"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	utilnet "k8s.io/utils/net"
 )
 
@@ -214,3 +214,30 @@ func TestNeedsHealthCheck(t *testing.T) {
 		},
 	})
 }
+
+func TestRequestsOnlyLocalTrafficForInternal(t *testing.T) {
+	checkRequestsOnlyLocalTrafficForInternal := func(expected bool, service *v1.Service) {
+		res := RequestsOnlyLocalTrafficForInternal(service)
+		if res != expected {
+			t.Errorf("Expected internal local traffic = %v, got %v",
+				expected, res)
+		}
+	}
+
+	// default InternalTrafficPolicy is nil
+	checkRequestsOnlyLocalTrafficForInternal(false, &v1.Service{})
+
+	local := v1.ServiceInternalTrafficPolicyLocal
+	checkRequestsOnlyLocalTrafficForInternal(true, &v1.Service{
+		Spec: v1.ServiceSpec{
+			InternalTrafficPolicy: &local,
+		},
+	})
+
+	cluster := v1.ServiceInternalTrafficPolicyCluster
+	checkRequestsOnlyLocalTrafficForInternal(false, &v1.Service{
+		Spec: v1.ServiceSpec{
+			InternalTrafficPolicy: &cluster,
+		},
+	})
+}

pkg/apis/core/types.go

@@ -3475,6 +3475,19 @@ const (
 	ServiceTypeExternalName ServiceType = "ExternalName"
 )
 
+// ServiceInternalTrafficPolicyType describes the type of traffic routing for
+// internal traffic
+type ServiceInternalTrafficPolicyType string
+
+const (
+	// ServiceInternalTrafficPolicyCluster routes traffic to all endpoints
+	ServiceInternalTrafficPolicyCluster ServiceInternalTrafficPolicyType = "Cluster"
+
+	// ServiceInternalTrafficPolicyLocal only routes to node-local
+	// endpoints, otherwise drops the traffic
+	ServiceInternalTrafficPolicyLocal ServiceInternalTrafficPolicyType = "Local"
+)
+
 // ServiceExternalTrafficPolicyType string
 type ServiceExternalTrafficPolicyType string
 
@@ -3739,9 +3752,19 @@ type ServiceSpec struct {
 	// implementation (e.g. cloud providers) should ignore Services that set this field.
 	// This field can only be set when creating or updating a Service to type 'LoadBalancer'.
 	// Once set, it can not be changed. This field will be wiped when a service is updated to a non 'LoadBalancer' type.
-	// featureGate=LoadBalancerClass
+	// +featureGate=LoadBalancerClass
 	// +optional
 	LoadBalancerClass *string
+
+	// InternalTrafficPolicy specifies if the cluster internal traffic
+	// should be routed to all endpoints or node-local endpoints only.
+	// "Cluster" routes internal traffic to a Service to all endpoints.
+	// "Local" routes traffic to node-local endpoints only, traffic is
+	// dropped if no node-local endpoints are ready.
+	// The default value is "Cluster".
+	// +featureGate=ServiceInternalTrafficPolicy
+	// +optional
+	InternalTrafficPolicy *ServiceInternalTrafficPolicyType
 }
 
 // ServicePort represents the port on which the service is exposed

pkg/apis/core/v1/defaults.go

@@ -131,6 +131,11 @@ func SetDefaults_Service(obj *v1.Service) {
 		obj.Spec.ExternalTrafficPolicy = v1.ServiceExternalTrafficPolicyTypeCluster
 	}
 
+	if utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) && obj.Spec.InternalTrafficPolicy == nil {
+		serviceInternalTrafficPolicyCluster := v1.ServiceInternalTrafficPolicyCluster
+		obj.Spec.InternalTrafficPolicy = &serviceInternalTrafficPolicyCluster
+	}
+
 	if utilfeature.DefaultFeatureGate.Enabled(features.ServiceLBNodePortControl) {
 		if obj.Spec.Type == v1.ServiceTypeLoadBalancer {
 			if obj.Spec.AllocateLoadBalancerNodePorts == nil {

pkg/apis/core/v1/defaults_test.go

@@ -29,8 +29,11 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/diff"
 	"k8s.io/apimachinery/pkg/util/intstr"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	"k8s.io/kubernetes/pkg/api/legacyscheme"
 	corev1 "k8s.io/kubernetes/pkg/apis/core/v1"
+	"k8s.io/kubernetes/pkg/features"
 	utilpointer "k8s.io/utils/pointer"
 
 	// ensure types are installed
@@ -1798,3 +1801,64 @@ func TestSetDefaultEnableServiceLinks(t *testing.T) {
 		t.Errorf("Expected enableServiceLinks value: %+v\ngot: %+v\n", v1.DefaultEnableServiceLinks, *output.Spec.EnableServiceLinks)
 	}
 }
+
+func TestSetDefaultServiceInternalTrafficPolicy(t *testing.T) {
+	cluster := v1.ServiceInternalTrafficPolicyCluster
+	local := v1.ServiceInternalTrafficPolicyLocal
+	testCases := []struct {
+		name                          string
+		expectedInternalTrafficPolicy v1.ServiceInternalTrafficPolicyType
+		svc                           v1.Service
+		featureGateOn                 bool
+	}{
+		{
+			name:                          "must set default internalTrafficPolicy",
+			expectedInternalTrafficPolicy: v1.ServiceInternalTrafficPolicyCluster,
+			svc:                           v1.Service{},
+			featureGateOn:                 true,
+		},
+		{
+			name:                          "must not set default internalTrafficPolicy when it's cluster",
+			expectedInternalTrafficPolicy: v1.ServiceInternalTrafficPolicyCluster,
+			svc: v1.Service{
+				Spec: v1.ServiceSpec{
+					InternalTrafficPolicy: &cluster,
+				},
+			},
+			featureGateOn: true,
+		},
+		{
+			name:                          "must not set default internalTrafficPolicy when it's local",
+			expectedInternalTrafficPolicy: v1.ServiceInternalTrafficPolicyLocal,
+			svc: v1.Service{
+				Spec: v1.ServiceSpec{
+					InternalTrafficPolicy: &local,
+				},
+			},
+			featureGateOn: true,
+		},
+		{
+			name:                          "must not set default internalTrafficPolicy when gate is disabled",
+			expectedInternalTrafficPolicy: "",
+			svc:                           v1.Service{},
+			featureGateOn:                 false,
+		},
+	}
+	for _, test := range testCases {
+		t.Run(test.name, func(t *testing.T) {
+			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceInternalTrafficPolicy, test.featureGateOn)()
+			obj := roundTrip(t, runtime.Object(&test.svc))
+			svc := obj.(*v1.Service)
+
+			if test.expectedInternalTrafficPolicy == "" {
+				if svc.Spec.InternalTrafficPolicy != nil {
+					t.Fatalf("expected .spec.internalTrafficPolicy: null, got %v", *svc.Spec.InternalTrafficPolicy)
+				}
+			} else {
+				if *svc.Spec.InternalTrafficPolicy != test.expectedInternalTrafficPolicy {
+					t.Fatalf("expected .spec.internalTrafficPolicy: %v got %v", test.expectedInternalTrafficPolicy, *svc.Spec.InternalTrafficPolicy)
+				}
+			}
+		})
+	}
+}

pkg/apis/core/v1/zz_generated.conversion.go

@@ -7636,6 +7636,7 @@ func autoConvert_v1_ServiceSpec_To_core_ServiceSpec(in *v1.ServiceSpec, out *cor
 	out.IPFamilyPolicy = (*core.IPFamilyPolicyType)(unsafe.Pointer(in.IPFamilyPolicy))
 	out.AllocateLoadBalancerNodePorts = (*bool)(unsafe.Pointer(in.AllocateLoadBalancerNodePorts))
 	out.LoadBalancerClass = (*string)(unsafe.Pointer(in.LoadBalancerClass))
+	out.InternalTrafficPolicy = (*core.ServiceInternalTrafficPolicyType)(unsafe.Pointer(in.InternalTrafficPolicy))
 	return nil
 }
 
@@ -7664,6 +7665,7 @@ func autoConvert_core_ServiceSpec_To_v1_ServiceSpec(in *core.ServiceSpec, out *v
 	out.TopologyKeys = *(*[]string)(unsafe.Pointer(&in.TopologyKeys))
 	out.AllocateLoadBalancerNodePorts = (*bool)(unsafe.Pointer(in.AllocateLoadBalancerNodePorts))
 	out.LoadBalancerClass = (*string)(unsafe.Pointer(in.LoadBalancerClass))
+	out.InternalTrafficPolicy = (*v1.ServiceInternalTrafficPolicyType)(unsafe.Pointer(in.InternalTrafficPolicy))
 	return nil
 }
 

pkg/apis/core/validation/validation.go

@@ -4171,6 +4171,8 @@ var supportedSessionAffinityType = sets.NewString(string(core.ServiceAffinityCli
 var supportedServiceType = sets.NewString(string(core.ServiceTypeClusterIP), string(core.ServiceTypeNodePort),
 	string(core.ServiceTypeLoadBalancer), string(core.ServiceTypeExternalName))
 
+var supportedServiceInternalTrafficPolicy = sets.NewString(string(core.ServiceInternalTrafficPolicyCluster), string(core.ServiceExternalTrafficPolicyTypeLocal))
+
 var supportedServiceIPFamily = sets.NewString(string(core.IPv4Protocol), string(core.IPv6Protocol))
 var supportedServiceIPFamilyPolicy = sets.NewString(string(core.IPFamilyPolicySingleStack), string(core.IPFamilyPolicyPreferDualStack), string(core.IPFamilyPolicyRequireDualStack))
 
@@ -4378,6 +4380,10 @@ func ValidateService(service *core.Service) field.ErrorList {
 
 	// external traffic fields
 	allErrs = append(allErrs, validateServiceExternalTrafficFieldsValue(service)...)
+
+	// internal traffic policy field
+	allErrs = append(allErrs, validateServiceInternalTrafficFieldsValue(service)...)
+
 	return allErrs
 }
 
@@ -4446,6 +4452,24 @@ func validateServiceExternalTrafficFieldsValue(service *core.Service) field.Erro
 	return allErrs
 }
 
+// validateServiceInternalTrafficFieldsValue validates InternalTraffic related
+// spec have legal value.
+func validateServiceInternalTrafficFieldsValue(service *core.Service) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	if utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) {
+		if service.Spec.InternalTrafficPolicy == nil {
+			allErrs = append(allErrs, field.Required(field.NewPath("spec").Child("internalTrafficPolicy"), ""))
+		}
+	}
+
+	if service.Spec.InternalTrafficPolicy != nil && !supportedServiceInternalTrafficPolicy.Has(string(*service.Spec.InternalTrafficPolicy)) {
+		allErrs = append(allErrs, field.NotSupported(field.NewPath("spec").Child("internalTrafficPolicy"), *service.Spec.InternalTrafficPolicy, supportedServiceInternalTrafficPolicy.List()))
+	}
+
+	return allErrs
+}
+
 // ValidateServiceExternalTrafficFieldsCombination validates if ExternalTrafficPolicy,
 // HealthCheckNodePort and Type combination are legal. For update, it should be called
 // after clearing externalTraffic related fields for the ease of transitioning between

pkg/apis/core/validation/validation_test.go

@@ -33,6 +33,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/validation"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/component-base/featuregate"
 	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	"k8s.io/kubernetes/pkg/apis/core"
 	"k8s.io/kubernetes/pkg/capabilities"
@@ -10135,9 +10136,10 @@ func TestValidateServiceCreate(t *testing.T) {
 	preferDualStack := core.IPFamilyPolicyPreferDualStack
 
 	testCases := []struct {
-		name     string
-		tweakSvc func(svc *core.Service) // given a basic valid service, each test case can customize it
-		numErrs  int
+		name         string
+		tweakSvc     func(svc *core.Service) // given a basic valid service, each test case can customize it
+		numErrs      int
+		featureGates []featuregate.Feature
 	}{
 		{
 			name: "missing namespace",
@@ -10750,6 +10752,22 @@ func TestValidateServiceCreate(t *testing.T) {
 			},
 			numErrs: 1,
 		},
+		{
+			name: "nil internalTraffic field when feature gate is on",
+			tweakSvc: func(s *core.Service) {
+				s.Spec.InternalTrafficPolicy = nil
+			},
+			featureGates: []featuregate.Feature{features.ServiceInternalTrafficPolicy},
+			numErrs:      1,
+		},
+		{
+			name: "invalid internalTraffic field",
+			tweakSvc: func(s *core.Service) {
+				invalid := core.ServiceInternalTrafficPolicyType("invalid")
+				s.Spec.InternalTrafficPolicy = &invalid
+			},
+			numErrs: 1,
+		},
 		{
 			name: "nagative healthCheckNodePort field",
 			tweakSvc: func(s *core.Service) {
@@ -11323,6 +11341,9 @@ func TestValidateServiceCreate(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
+			for i := range tc.featureGates {
+				defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, tc.featureGates[i], true)()
+			}
 			svc := makeValidService()
 			tc.tweakSvc(&svc)
 			errs := ValidateServiceCreate(&svc)

pkg/apis/core/zz_generated.deepcopy.go

@@ -5335,6 +5335,11 @@ func (in *ServiceSpec) DeepCopyInto(out *ServiceSpec) {
 		*out = new(string)
 		**out = **in
 	}
+	if in.InternalTrafficPolicy != nil {
+		in, out := &in.InternalTrafficPolicy, &out.InternalTrafficPolicy
+		*out = new(ServiceInternalTrafficPolicyType)
+		**out = **in
+	}
 	return
 }
 

pkg/features/kube_features.go

@@ -708,6 +708,12 @@ const (
 	//
 	// Enable Scope and Namespace fields on IngressClassParametersReference.
 	IngressClassNamespacedParams featuregate.Feature = "IngressClassNamespacedParams"
+
+	// owner: @maplain @andrewsykim
+	// alpha: v1.21
+	//
+	// Enables node-local routing for Service internal traffic
+	ServiceInternalTrafficPolicy featuregate.Feature = "ServiceInternalTrafficPolicy"
 )
 
 func init() {
@@ -815,6 +821,7 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 	ServiceLoadBalancerClass:                       {Default: false, PreRelease: featuregate.Alpha},
 	LogarithmicScaleDown:                           {Default: false, PreRelease: featuregate.Alpha},
 	IngressClassNamespacedParams:                   {Default: false, PreRelease: featuregate.Alpha},
+	ServiceInternalTrafficPolicy:                   {Default: false, PreRelease: featuregate.Alpha},
 
 	// inherited features from generic apiserver, relisted here to get a conflict if it is changed
 	// unintentionally on either side:

pkg/proxy/iptables/proxier.go

@@ -1029,6 +1029,13 @@ func (proxier *Proxier) syncProxyRules() {
 			allEndpoints = proxy.FilterTopologyEndpoint(proxier.nodeLabels, svcInfo.TopologyKeys(), allEndpoints)
 		}
 
+		// Service InternalTrafficPolicy is only enabled when all of the
+		// following are true:
+		// 1. InternalTrafficPolicy is Local
+		// 2. ServiceInternalTrafficPolicy feature gate is on
+		if utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) && svcInfo.OnlyNodeLocalEndpointsForInternal() {
+			allEndpoints = proxy.FilterLocalEndpoint(svcInfo.InternalTrafficPolicy(), allEndpoints)
+		}
 		readyEndpoints := make([]proxy.Endpoint, 0, len(allEndpoints))
 		for _, endpoint := range allEndpoints {
 			if !endpoint.IsReady() {

pkg/proxy/iptables/proxier_test.go

@@ -32,8 +32,11 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/intstr"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	"k8s.io/component-base/metrics/testutil"
 	"k8s.io/klog/v2"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/proxy"
 	"k8s.io/kubernetes/pkg/proxy/metrics"
 
@@ -3056,3 +3059,219 @@ func TestProxierMetricsIptablesTotalRules(t *testing.T) {
 }
 
 // TODO(thockin): add *more* tests for syncProxyRules() or break it down further and test the pieces.
+
+// This test ensures that the iptables proxier supports translating Endpoints to
+// iptables output when internalTrafficPolicy is specified
+func TestInternalTrafficPolicyE2E(t *testing.T) {
+	type endpoint struct {
+		ip       string
+		hostname string
+	}
+
+	cluster := v1.ServiceInternalTrafficPolicyCluster
+	local := v1.ServiceInternalTrafficPolicyLocal
+
+	clusterExpectedIPTables := `*filter
+:KUBE-SERVICES - [0:0]
+:KUBE-EXTERNAL-SERVICES - [0:0]
+:KUBE-FORWARD - [0:0]
+:KUBE-NODEPORTS - [0:0]
+-A KUBE-FORWARD -m conntrack --ctstate INVALID -j DROP
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding rules" -m mark --mark 0x4000/0x4000 -j ACCEPT
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding conntrack pod source rule" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding conntrack pod destination rule" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+COMMIT
+*nat
+:KUBE-SERVICES - [0:0]
+:KUBE-NODEPORTS - [0:0]
+:KUBE-POSTROUTING - [0:0]
+:KUBE-MARK-MASQ - [0:0]
+:KUBE-SVC-AQI2S6QIMU7PVVRP - [0:0]
+:KUBE-SEP-3JOIVZTXZZRGORX4 - [0:0]
+:KUBE-SEP-IO5XOSKPAXIFQXAJ - [0:0]
+:KUBE-SEP-XGJFVO3L2O5SRFNT - [0:0]
+-A KUBE-POSTROUTING -m mark ! --mark 0x4000/0x4000 -j RETURN
+-A KUBE-POSTROUTING -j MARK --xor-mark 0x4000
+-A KUBE-POSTROUTING -m comment --comment "kubernetes service traffic requiring SNAT" -j MASQUERADE
+-A KUBE-MARK-MASQ -j MARK --or-mark 0x4000
+-A KUBE-SERVICES -m comment --comment "ns1/svc1 cluster IP" -m tcp -p tcp -d 172.20.1.1/32 --dport 80 ! -s 10.0.0.0/24 -j KUBE-MARK-MASQ
+-A KUBE-SERVICES -m comment --comment "ns1/svc1 cluster IP" -m tcp -p tcp -d 172.20.1.1/32 --dport 80 -j KUBE-SVC-AQI2S6QIMU7PVVRP
+-A KUBE-SVC-AQI2S6QIMU7PVVRP -m comment --comment ns1/svc1 -m statistic --mode random --probability 0.3333333333 -j KUBE-SEP-3JOIVZTXZZRGORX4
+-A KUBE-SEP-3JOIVZTXZZRGORX4 -m comment --comment ns1/svc1 -s 10.0.1.1/32 -j KUBE-MARK-MASQ
+-A KUBE-SEP-3JOIVZTXZZRGORX4 -m comment --comment ns1/svc1 -m tcp -p tcp -j DNAT --to-destination 10.0.1.1:80
+-A KUBE-SVC-AQI2S6QIMU7PVVRP -m comment --comment ns1/svc1 -m statistic --mode random --probability 0.5000000000 -j KUBE-SEP-IO5XOSKPAXIFQXAJ
+-A KUBE-SEP-IO5XOSKPAXIFQXAJ -m comment --comment ns1/svc1 -s 10.0.1.2/32 -j KUBE-MARK-MASQ
+-A KUBE-SEP-IO5XOSKPAXIFQXAJ -m comment --comment ns1/svc1 -m tcp -p tcp -j DNAT --to-destination 10.0.1.2:80
+-A KUBE-SVC-AQI2S6QIMU7PVVRP -m comment --comment ns1/svc1 -j KUBE-SEP-XGJFVO3L2O5SRFNT
+-A KUBE-SEP-XGJFVO3L2O5SRFNT -m comment --comment ns1/svc1 -s 10.0.1.3/32 -j KUBE-MARK-MASQ
+-A KUBE-SEP-XGJFVO3L2O5SRFNT -m comment --comment ns1/svc1 -m tcp -p tcp -j DNAT --to-destination 10.0.1.3:80
+-A KUBE-SERVICES -m comment --comment "kubernetes service nodeports; NOTE: this must be the last rule in this chain" -m addrtype --dst-type LOCAL -j KUBE-NODEPORTS
+COMMIT
+`
+
+	testCases := []struct {
+		name                      string
+		internalTrafficPolicy     *v1.ServiceInternalTrafficPolicyType
+		featureGateOn             bool
+		endpoints                 []endpoint
+		expectEndpointRule        bool
+		expectedIPTablesWithSlice string
+	}{
+		{
+			name:                  "internalTrafficPolicy is cluster",
+			internalTrafficPolicy: &cluster,
+			featureGateOn:         true,
+			endpoints: []endpoint{
+				{"10.0.1.1", testHostname},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectEndpointRule:        true,
+			expectedIPTablesWithSlice: clusterExpectedIPTables,
+		},
+		{
+			name:                  "internalTrafficPolicy is local and there is non-zero local endpoints",
+			internalTrafficPolicy: &local,
+			featureGateOn:         true,
+			endpoints: []endpoint{
+				{"10.0.1.1", testHostname},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectEndpointRule: true,
+			expectedIPTablesWithSlice: `*filter
+:KUBE-SERVICES - [0:0]
+:KUBE-EXTERNAL-SERVICES - [0:0]
+:KUBE-FORWARD - [0:0]
+:KUBE-NODEPORTS - [0:0]
+-A KUBE-FORWARD -m conntrack --ctstate INVALID -j DROP
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding rules" -m mark --mark 0x4000/0x4000 -j ACCEPT
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding conntrack pod source rule" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding conntrack pod destination rule" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+COMMIT
+*nat
+:KUBE-SERVICES - [0:0]
+:KUBE-NODEPORTS - [0:0]
+:KUBE-POSTROUTING - [0:0]
+:KUBE-MARK-MASQ - [0:0]
+:KUBE-SVC-AQI2S6QIMU7PVVRP - [0:0]
+:KUBE-SEP-3JOIVZTXZZRGORX4 - [0:0]
+-A KUBE-POSTROUTING -m mark ! --mark 0x4000/0x4000 -j RETURN
+-A KUBE-POSTROUTING -j MARK --xor-mark 0x4000
+-A KUBE-POSTROUTING -m comment --comment "kubernetes service traffic requiring SNAT" -j MASQUERADE
+-A KUBE-MARK-MASQ -j MARK --or-mark 0x4000
+-A KUBE-SERVICES -m comment --comment "ns1/svc1 cluster IP" -m tcp -p tcp -d 172.20.1.1/32 --dport 80 ! -s 10.0.0.0/24 -j KUBE-MARK-MASQ
+-A KUBE-SERVICES -m comment --comment "ns1/svc1 cluster IP" -m tcp -p tcp -d 172.20.1.1/32 --dport 80 -j KUBE-SVC-AQI2S6QIMU7PVVRP
+-A KUBE-SVC-AQI2S6QIMU7PVVRP -m comment --comment ns1/svc1 -j KUBE-SEP-3JOIVZTXZZRGORX4
+-A KUBE-SEP-3JOIVZTXZZRGORX4 -m comment --comment ns1/svc1 -s 10.0.1.1/32 -j KUBE-MARK-MASQ
+-A KUBE-SEP-3JOIVZTXZZRGORX4 -m comment --comment ns1/svc1 -m tcp -p tcp -j DNAT --to-destination 10.0.1.1:80
+-A KUBE-SERVICES -m comment --comment "kubernetes service nodeports; NOTE: this must be the last rule in this chain" -m addrtype --dst-type LOCAL -j KUBE-NODEPORTS
+COMMIT
+`,
+		},
+		{
+			name:                  "internalTrafficPolicy is local and there is zero local endpoint",
+			internalTrafficPolicy: &local,
+			featureGateOn:         true,
+			endpoints: []endpoint{
+				{"10.0.1.1", "host0"},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectEndpointRule: false,
+			expectedIPTablesWithSlice: `*filter
+:KUBE-SERVICES - [0:0]
+:KUBE-EXTERNAL-SERVICES - [0:0]
+:KUBE-FORWARD - [0:0]
+:KUBE-NODEPORTS - [0:0]
+-A KUBE-SERVICES -m comment --comment "ns1/svc1 has no endpoints" -m tcp -p tcp -d 172.20.1.1/32 --dport 80 -j REJECT
+-A KUBE-FORWARD -m conntrack --ctstate INVALID -j DROP
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding rules" -m mark --mark 0x4000/0x4000 -j ACCEPT
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding conntrack pod source rule" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+-A KUBE-FORWARD -m comment --comment "kubernetes forwarding conntrack pod destination rule" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+COMMIT
+*nat
+:KUBE-SERVICES - [0:0]
+:KUBE-NODEPORTS - [0:0]
+:KUBE-POSTROUTING - [0:0]
+:KUBE-MARK-MASQ - [0:0]
+-A KUBE-POSTROUTING -m mark ! --mark 0x4000/0x4000 -j RETURN
+-A KUBE-POSTROUTING -j MARK --xor-mark 0x4000
+-A KUBE-POSTROUTING -m comment --comment "kubernetes service traffic requiring SNAT" -j MASQUERADE
+-A KUBE-MARK-MASQ -j MARK --or-mark 0x4000
+-A KUBE-SERVICES -m comment --comment "kubernetes service nodeports; NOTE: this must be the last rule in this chain" -m addrtype --dst-type LOCAL -j KUBE-NODEPORTS
+COMMIT
+`,
+		},
+		{
+			name:                  "internalTrafficPolicy is local and there is non-zero local endpoint with feature gate off",
+			internalTrafficPolicy: &local,
+			featureGateOn:         false,
+			endpoints: []endpoint{
+				{"10.0.1.1", testHostname},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectEndpointRule:        false,
+			expectedIPTablesWithSlice: clusterExpectedIPTables,
+		},
+	}
+
+	for _, tc := range testCases {
+		defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceInternalTrafficPolicy, tc.featureGateOn)()
+		ipt := iptablestest.NewFake()
+		fp := NewFakeProxier(ipt, true)
+		fp.OnServiceSynced()
+		fp.OnEndpointsSynced()
+		fp.OnEndpointSlicesSynced()
+
+		serviceName := "svc1"
+		namespaceName := "ns1"
+
+		svc := &v1.Service{
+			ObjectMeta: metav1.ObjectMeta{Name: serviceName, Namespace: namespaceName},
+			Spec: v1.ServiceSpec{
+				ClusterIP: "172.20.1.1",
+				Selector:  map[string]string{"foo": "bar"},
+				Ports:     []v1.ServicePort{{Name: "", Port: 80, Protocol: v1.ProtocolTCP}},
+			},
+		}
+		if tc.internalTrafficPolicy != nil {
+			svc.Spec.InternalTrafficPolicy = tc.internalTrafficPolicy
+		}
+
+		fp.OnServiceAdd(svc)
+
+		tcpProtocol := v1.ProtocolTCP
+		endpointSlice := &discovery.EndpointSlice{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      fmt.Sprintf("%s-1", serviceName),
+				Namespace: namespaceName,
+				Labels:    map[string]string{discovery.LabelServiceName: serviceName},
+			},
+			Ports: []discovery.EndpointPort{{
+				Name:     utilpointer.StringPtr(""),
+				Port:     utilpointer.Int32Ptr(80),
+				Protocol: &tcpProtocol,
+			}},
+			AddressType: discovery.AddressTypeIPv4,
+		}
+		for _, ep := range tc.endpoints {
+			endpointSlice.Endpoints = append(endpointSlice.Endpoints, discovery.Endpoint{
+				Addresses:  []string{ep.ip},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+				Topology:   map[string]string{"kubernetes.io/hostname": ep.hostname},
+			})
+		}
+
+		fp.OnEndpointSliceAdd(endpointSlice)
+		fp.syncProxyRules()
+		assert.Equal(t, tc.expectedIPTablesWithSlice, fp.iptablesData.String())
+
+		if tc.expectEndpointRule {
+			fp.OnEndpointSliceDelete(endpointSlice)
+			fp.syncProxyRules()
+			assert.NotEqual(t, tc.expectedIPTablesWithSlice, fp.iptablesData.String())
+		}
+	}
+}

pkg/proxy/ipvs/proxier.go

@@ -1236,7 +1236,7 @@ func (proxier *Proxier) syncProxyRules() {
 			activeBindAddrs[serv.Address.String()] = true
 			// ExternalTrafficPolicy only works for NodePort and external LB traffic, does not affect ClusterIP
 			// So we still need clusterIP rules in onlyNodeLocalEndpoints mode.
-			if err := proxier.syncEndpoint(svcName, false, serv); err != nil {
+			if err := proxier.syncEndpoint(svcName, false, svcInfo.OnlyNodeLocalEndpointsForInternal(), serv); err != nil {
 				klog.Errorf("Failed to sync endpoint for service: %v, err: %v", serv, err)
 			}
 		} else {
@@ -1319,7 +1319,8 @@ func (proxier *Proxier) syncProxyRules() {
 				activeBindAddrs[serv.Address.String()] = true
 
 				onlyNodeLocalEndpoints := svcInfo.OnlyNodeLocalEndpoints()
-				if err := proxier.syncEndpoint(svcName, onlyNodeLocalEndpoints, serv); err != nil {
+				onlyNodeLocalEndpointsForInternal := svcInfo.OnlyNodeLocalEndpointsForInternal()
+				if err := proxier.syncEndpoint(svcName, onlyNodeLocalEndpoints, onlyNodeLocalEndpointsForInternal, serv); err != nil {
 					klog.Errorf("Failed to sync endpoint for service: %v, err: %v", serv, err)
 				}
 			} else {
@@ -1420,7 +1421,7 @@ func (proxier *Proxier) syncProxyRules() {
 				if err := proxier.syncService(svcNameString, serv, true, bindedAddresses); err == nil {
 					activeIPVSServices[serv.String()] = true
 					activeBindAddrs[serv.Address.String()] = true
-					if err := proxier.syncEndpoint(svcName, svcInfo.OnlyNodeLocalEndpoints(), serv); err != nil {
+					if err := proxier.syncEndpoint(svcName, svcInfo.OnlyNodeLocalEndpoints(), svcInfo.OnlyNodeLocalEndpointsForInternal(), serv); err != nil {
 						klog.Errorf("Failed to sync endpoint for service: %v, err: %v", serv, err)
 					}
 				} else {
@@ -1579,7 +1580,7 @@ func (proxier *Proxier) syncProxyRules() {
 				// There is no need to bind Node IP to dummy interface, so set parameter `bindAddr` to `false`.
 				if err := proxier.syncService(svcNameString, serv, false, bindedAddresses); err == nil {
 					activeIPVSServices[serv.String()] = true
-					if err := proxier.syncEndpoint(svcName, svcInfo.OnlyNodeLocalEndpoints(), serv); err != nil {
+					if err := proxier.syncEndpoint(svcName, svcInfo.OnlyNodeLocalEndpoints(), svcInfo.OnlyNodeLocalEndpointsForInternal(), serv); err != nil {
 						klog.Errorf("Failed to sync endpoint for service: %v, err: %v", serv, err)
 					}
 				} else {
@@ -2030,7 +2031,7 @@ func (proxier *Proxier) syncService(svcName string, vs *utilipvs.VirtualServer,
 	return nil
 }
 
-func (proxier *Proxier) syncEndpoint(svcPortName proxy.ServicePortName, onlyNodeLocalEndpoints bool, vs *utilipvs.VirtualServer) error {
+func (proxier *Proxier) syncEndpoint(svcPortName proxy.ServicePortName, onlyNodeLocalEndpoints bool, onlyNodeLocalEndpointsForInternal bool, vs *utilipvs.VirtualServer) error {
 	appliedVirtualServer, err := proxier.ipvs.GetVirtualServer(vs)
 	if err != nil {
 		klog.Errorf("Failed to get IPVS service, error: %v", err)
@@ -2065,6 +2066,14 @@ func (proxier *Proxier) syncEndpoint(svcPortName proxy.ServicePortName, onlyNode
 		endpoints = proxy.FilterTopologyEndpoint(proxier.nodeLabels, proxier.serviceMap[svcPortName].TopologyKeys(), endpoints)
 	}
 
+	// Service InternalTrafficPolicy is only enabled when all of the
+	// following are true:
+	// 1. InternalTrafficPolicy is PreferLocal or Local
+	// 2. ServiceInternalTrafficPolicy feature gate is on
+	if utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) && onlyNodeLocalEndpointsForInternal {
+		endpoints = proxy.FilterLocalEndpoint(proxier.serviceMap[svcPortName].InternalTrafficPolicy(), endpoints)
+	}
+
 	for _, epInfo := range endpoints {
 		if !epInfo.IsReady() {
 			continue

pkg/proxy/ipvs/proxier_test.go

@@ -33,6 +33,9 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/intstr"
 	"k8s.io/apimachinery/pkg/util/sets"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/proxy"
 	"k8s.io/kubernetes/pkg/proxy/healthcheck"
 	netlinktest "k8s.io/kubernetes/pkg/proxy/ipvs/testing"
@@ -4467,3 +4470,183 @@ func TestCreateAndLinkKubeChain(t *testing.T) {
 	assert.Equal(t, expectedNATChains, fp.natChains.String())
 	assert.Equal(t, expectedFilterChains, fp.filterChains.String())
 }
+
+// This test ensures that the iptables proxier supports translating Endpoints to
+// iptables output when internalTrafficPolicy is specified
+func TestTestInternalTrafficPolicyE2E(t *testing.T) {
+	type endpoint struct {
+		ip       string
+		hostname string
+	}
+
+	cluster := v1.ServiceInternalTrafficPolicyCluster
+	local := v1.ServiceInternalTrafficPolicyLocal
+
+	testCases := []struct {
+		name                     string
+		internalTrafficPolicy    *v1.ServiceInternalTrafficPolicyType
+		endpoints                []endpoint
+		expectVirtualServer      bool
+		expectLocalEntries       bool
+		expectLocalRealServerNum int
+		expectLocalRealServers   []string
+	}{
+		{
+			name:                  "internalTrafficPolicy is cluster with non-zero local endpoints",
+			internalTrafficPolicy: &cluster,
+			endpoints: []endpoint{
+				{"10.0.1.1", testHostname},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectVirtualServer:      true,
+			expectLocalEntries:       true,
+			expectLocalRealServerNum: 3,
+			expectLocalRealServers: []string{
+				"10.0.1.1:80",
+				"10.0.1.2:80",
+				"10.0.1.3:80",
+			},
+		},
+		{
+			name:                  "internalTrafficPolicy is cluster with zero local endpoints",
+			internalTrafficPolicy: &cluster,
+			endpoints: []endpoint{
+				{"10.0.1.1", "host0"},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectVirtualServer:      false,
+			expectLocalEntries:       false,
+			expectLocalRealServerNum: 3,
+			expectLocalRealServers: []string{
+				"10.0.1.1:80",
+				"10.0.1.2:80",
+				"10.0.1.3:80",
+			},
+		},
+		{
+			name:                  "internalTrafficPolicy is local with non-zero local endpoints",
+			internalTrafficPolicy: &local,
+			endpoints: []endpoint{
+				{"10.0.1.1", testHostname},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectVirtualServer:      true,
+			expectLocalEntries:       true,
+			expectLocalRealServerNum: 1,
+			expectLocalRealServers: []string{
+				"10.0.1.1:80",
+			},
+		},
+		{
+			name:                  "internalTrafficPolicy is local with zero local endpoints",
+			internalTrafficPolicy: &local,
+			endpoints: []endpoint{
+				{"10.0.1.1", "host0"},
+				{"10.0.1.2", "host1"},
+				{"10.0.1.3", "host2"},
+			},
+			expectVirtualServer:      false,
+			expectLocalEntries:       false,
+			expectLocalRealServerNum: 0,
+			expectLocalRealServers:   []string{},
+		},
+	}
+	for _, tc := range testCases {
+		defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceInternalTrafficPolicy, true)()
+
+		ipt := iptablestest.NewFake()
+		ipvs := ipvstest.NewFake()
+		ipset := ipsettest.NewFake(testIPSetVersion)
+		fp := NewFakeProxier(ipt, ipvs, ipset, nil, nil, true, v1.IPv4Protocol)
+		fp.servicesSynced = true
+		fp.endpointsSynced = true
+		fp.endpointSlicesSynced = true
+
+		// Add initial service
+		serviceName := "svc1"
+		namespaceName := "ns1"
+
+		svc := &v1.Service{
+			ObjectMeta: metav1.ObjectMeta{Name: serviceName, Namespace: namespaceName},
+			Spec: v1.ServiceSpec{
+				ClusterIP: "172.20.1.1",
+				Selector:  map[string]string{"foo": "bar"},
+				Ports:     []v1.ServicePort{{Name: "", TargetPort: intstr.FromInt(80), Protocol: v1.ProtocolTCP}},
+			},
+		}
+		if tc.internalTrafficPolicy != nil {
+			svc.Spec.InternalTrafficPolicy = tc.internalTrafficPolicy
+		}
+
+		fp.OnServiceAdd(svc)
+
+		// Add initial endpoint slice
+		tcpProtocol := v1.ProtocolTCP
+		endpointSlice := &discovery.EndpointSlice{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      fmt.Sprintf("%s-1", serviceName),
+				Namespace: namespaceName,
+				Labels:    map[string]string{discovery.LabelServiceName: serviceName},
+			},
+			Ports: []discovery.EndpointPort{{
+				Name:     utilpointer.StringPtr(""),
+				Port:     utilpointer.Int32Ptr(80),
+				Protocol: &tcpProtocol,
+			}},
+			AddressType: discovery.AddressTypeIPv4,
+		}
+
+		for _, ep := range tc.endpoints {
+			endpointSlice.Endpoints = append(endpointSlice.Endpoints, discovery.Endpoint{
+				Addresses:  []string{ep.ip},
+				Conditions: discovery.EndpointConditions{Ready: utilpointer.BoolPtr(true)},
+				Topology:   map[string]string{"kubernetes.io/hostname": ep.hostname},
+			})
+		}
+
+		fp.OnEndpointSliceAdd(endpointSlice)
+		fp.syncProxyRules()
+
+		// Ensure that Proxier updates ipvs appropriately after EndpointSlice update
+		assert.NotNil(t, fp.ipsetList["KUBE-LOOP-BACK"])
+
+		activeEntries1 := fp.ipsetList["KUBE-LOOP-BACK"].activeEntries
+
+		if tc.expectLocalEntries {
+			assert.Equal(t, 1, activeEntries1.Len(), "Expected 1 active entry in KUBE-LOOP-BACK")
+		} else {
+			assert.Equal(t, 0, activeEntries1.Len(), "Expected no active entry in KUBE-LOOP-BACK")
+		}
+
+		if tc.expectVirtualServer {
+			virtualServers1, vsErr1 := ipvs.GetVirtualServers()
+			assert.Nil(t, vsErr1, "Expected no error getting virtual servers")
+
+			assert.Len(t, virtualServers1, 1, "Expected 1 virtual server")
+			realServers1, rsErr1 := ipvs.GetRealServers(virtualServers1[0])
+			assert.Nil(t, rsErr1, "Expected no error getting real servers")
+
+			assert.Len(t, realServers1, tc.expectLocalRealServerNum, fmt.Sprintf("Expected %d real servers", tc.expectLocalRealServerNum))
+			for i := 0; i < tc.expectLocalRealServerNum; i++ {
+				assert.Equal(t, realServers1[i].String(), tc.expectLocalRealServers[i])
+			}
+		}
+
+		fp.OnEndpointSliceDelete(endpointSlice)
+		fp.syncProxyRules()
+
+		// Ensure that Proxier updates ipvs appropriately after EndpointSlice delete
+		assert.NotNil(t, fp.ipsetList["KUBE-LOOP-BACK"])
+		activeEntries3 := fp.ipsetList["KUBE-LOOP-BACK"].activeEntries
+		assert.Equal(t, 0, activeEntries3.Len(), "Expected 0 active entries in KUBE-LOOP-BACK")
+		virtualServers2, vsErr2 := ipvs.GetVirtualServers()
+		assert.Nil(t, vsErr2, "Expected no error getting virtual servers")
+		assert.Len(t, virtualServers2, 1, "Expected 1 virtual server")
+		realServers2, rsErr2 := ipvs.GetRealServers(virtualServers2[0])
+		assert.Nil(t, rsErr2, "Expected no error getting real servers")
+		assert.Len(t, realServers2, 0, "Expected 0 real servers")
+	}
+}

pkg/proxy/service.go

@@ -28,8 +28,10 @@ import (
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/sets"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/client-go/tools/record"
 	apiservice "k8s.io/kubernetes/pkg/api/v1/service"
+	"k8s.io/kubernetes/pkg/features"
 	"k8s.io/kubernetes/pkg/proxy/metrics"
 	utilproxy "k8s.io/kubernetes/pkg/proxy/util"
 )
@@ -39,18 +41,20 @@ import (
 // or can be used for constructing a more specific ServiceInfo struct
 // defined by the proxier if needed.
 type BaseServiceInfo struct {
-	clusterIP                net.IP
-	port                     int
-	protocol                 v1.Protocol
-	nodePort                 int
-	loadBalancerStatus       v1.LoadBalancerStatus
-	sessionAffinityType      v1.ServiceAffinity
-	stickyMaxAgeSeconds      int
-	externalIPs              []string
-	loadBalancerSourceRanges []string
-	healthCheckNodePort      int
-	onlyNodeLocalEndpoints   bool
-	topologyKeys             []string
+	clusterIP                         net.IP
+	port                              int
+	protocol                          v1.Protocol
+	nodePort                          int
+	loadBalancerStatus                v1.LoadBalancerStatus
+	sessionAffinityType               v1.ServiceAffinity
+	stickyMaxAgeSeconds               int
+	externalIPs                       []string
+	loadBalancerSourceRanges          []string
+	healthCheckNodePort               int
+	onlyNodeLocalEndpoints            bool
+	onlyNodeLocalEndpointsForInternal bool
+	internalTrafficPolicy             *v1.ServiceInternalTrafficPolicyType
+	topologyKeys                      []string
 }
 
 var _ ServicePort = &BaseServiceInfo{}
@@ -119,6 +123,16 @@ func (info *BaseServiceInfo) OnlyNodeLocalEndpoints() bool {
 	return info.onlyNodeLocalEndpoints
 }
 
+// OnlyNodeLocalEndpointsForInternal is part of ServicePort interface
+func (info *BaseServiceInfo) OnlyNodeLocalEndpointsForInternal() bool {
+	return info.onlyNodeLocalEndpointsForInternal
+}
+
+// InternalTrafficPolicy is part of ServicePort interface
+func (info *BaseServiceInfo) InternalTrafficPolicy() *v1.ServiceInternalTrafficPolicyType {
+	return info.internalTrafficPolicy
+}
+
 // TopologyKeys is part of ServicePort interface.
 func (info *BaseServiceInfo) TopologyKeys() []string {
 	return info.topologyKeys
@@ -129,6 +143,10 @@ func (sct *ServiceChangeTracker) newBaseServiceInfo(port *v1.ServicePort, servic
 	if apiservice.RequestsOnlyLocalTraffic(service) {
 		onlyNodeLocalEndpoints = true
 	}
+	onlyNodeLocalEndpointsForInternal := false
+	if utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) {
+		onlyNodeLocalEndpointsForInternal = apiservice.RequestsOnlyLocalTrafficForInternal(service)
+	}
 	var stickyMaxAgeSeconds int
 	if service.Spec.SessionAffinity == v1.ServiceAffinityClientIP {
 		// Kube-apiserver side guarantees SessionAffinityConfig won't be nil when session affinity type is ClientIP
@@ -137,14 +155,16 @@ func (sct *ServiceChangeTracker) newBaseServiceInfo(port *v1.ServicePort, servic
 
 	clusterIP := utilproxy.GetClusterIPByFamily(sct.ipFamily, service)
 	info := &BaseServiceInfo{
-		clusterIP:              net.ParseIP(clusterIP),
-		port:                   int(port.Port),
-		protocol:               port.Protocol,
-		nodePort:               int(port.NodePort),
-		sessionAffinityType:    service.Spec.SessionAffinity,
-		stickyMaxAgeSeconds:    stickyMaxAgeSeconds,
-		onlyNodeLocalEndpoints: onlyNodeLocalEndpoints,
-		topologyKeys:           service.Spec.TopologyKeys,
+		clusterIP:                         net.ParseIP(clusterIP),
+		port:                              int(port.Port),
+		protocol:                          port.Protocol,
+		nodePort:                          int(port.NodePort),
+		sessionAffinityType:               service.Spec.SessionAffinity,
+		stickyMaxAgeSeconds:               stickyMaxAgeSeconds,
+		onlyNodeLocalEndpoints:            onlyNodeLocalEndpoints,
+		onlyNodeLocalEndpointsForInternal: onlyNodeLocalEndpointsForInternal,
+		internalTrafficPolicy:             service.Spec.InternalTrafficPolicy,
+		topologyKeys:                      service.Spec.TopologyKeys,
 	}
 
 	loadBalancerSourceRanges := make([]string, len(service.Spec.LoadBalancerSourceRanges))

pkg/proxy/topology.go

@@ -18,6 +18,8 @@ package proxy
 
 import (
 	v1 "k8s.io/api/core/v1"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/kubernetes/pkg/features"
 )
 
 // FilterTopologyEndpoint returns the appropriate endpoints based on the cluster
@@ -44,7 +46,7 @@ func FilterTopologyEndpoint(nodeLabels map[string]string, topologyKeys []string,
 		return endpoints
 	}
 
-	filteredEndpoint := []Endpoint{}
+	filteredEndpoints := []Endpoint{}
 
 	if len(nodeLabels) == 0 {
 		if topologyKeys[len(topologyKeys)-1] == v1.TopologyKeyAny {
@@ -54,7 +56,7 @@ func FilterTopologyEndpoint(nodeLabels map[string]string, topologyKeys []string,
 		}
 		// edge case: do not include any endpoints if topology key "Any" is
 		// not specified when we cannot determine current node's topology.
-		return filteredEndpoint
+		return filteredEndpoints
 	}
 
 	for _, key := range topologyKeys {
@@ -69,12 +71,40 @@ func FilterTopologyEndpoint(nodeLabels map[string]string, topologyKeys []string,
 		for _, ep := range endpoints {
 			topology := ep.GetTopology()
 			if value, found := topology[key]; found && value == topologyValue {
-				filteredEndpoint = append(filteredEndpoint, ep)
+				filteredEndpoints = append(filteredEndpoints, ep)
 			}
 		}
-		if len(filteredEndpoint) > 0 {
-			return filteredEndpoint
+		if len(filteredEndpoints) > 0 {
+			return filteredEndpoints
 		}
 	}
-	return filteredEndpoint
+	return filteredEndpoints
+}
+
+// FilterLocalEndpoint returns the node local endpoints based on configured
+// InternalTrafficPolicy.
+//
+// If ServiceInternalTrafficPolicy feature gate is off, returns the original
+// endpoints slice.
+// Otherwise, if InternalTrafficPolicy is Local, only return the node local endpoints.
+func FilterLocalEndpoint(internalTrafficPolicy *v1.ServiceInternalTrafficPolicyType, endpoints []Endpoint) []Endpoint {
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) {
+		return endpoints
+	}
+	if internalTrafficPolicy == nil || *internalTrafficPolicy == v1.ServiceInternalTrafficPolicyCluster {
+		return endpoints
+	}
+
+	var filteredEndpoints []Endpoint
+
+	// Get all the local endpoints
+	for _, ep := range endpoints {
+		if ep.GetIsLocal() {
+			filteredEndpoints = append(filteredEndpoints, ep)
+		}
+	}
+
+	// When internalTrafficPolicy is Local, only return the node local
+	// endpoints
+	return filteredEndpoints
 }

pkg/proxy/topology_test.go

@@ -22,6 +22,9 @@ import (
 
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/types"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
+	"k8s.io/kubernetes/pkg/features"
 )
 
 func TestFilterTopologyEndpoint(t *testing.T) {
@@ -476,3 +479,97 @@ func TestFilterTopologyEndpoint(t *testing.T) {
 		})
 	}
 }
+
+func TestFilterLocalEndpoint(t *testing.T) {
+	cluster := v1.ServiceInternalTrafficPolicyCluster
+	local := v1.ServiceInternalTrafficPolicyLocal
+
+	testCases := []struct {
+		name                  string
+		internalTrafficPolicy *v1.ServiceInternalTrafficPolicyType
+		endpoints             []Endpoint
+		expected              []Endpoint
+		featureGateOn         bool
+	}{
+		{
+			name:                  "no internalTrafficPolicy with empty endpoints",
+			internalTrafficPolicy: nil,
+			endpoints:             []Endpoint{},
+			expected:              []Endpoint{},
+			featureGateOn:         true,
+		},
+		{
+			name:                  "no internalTrafficPolicy with non-empty endpoints",
+			internalTrafficPolicy: nil,
+			endpoints: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+			},
+			expected: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+			},
+			featureGateOn: true,
+		},
+		{
+			name:                  "internalTrafficPolicy is cluster",
+			internalTrafficPolicy: &cluster,
+			endpoints: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+			},
+			expected: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+			},
+			featureGateOn: true,
+		},
+		{
+			name:                  "internalTrafficPolicy is local with non-zero local endpoints",
+			internalTrafficPolicy: &local,
+			endpoints: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+			},
+			expected: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+			},
+			featureGateOn: true,
+		},
+		{
+			name:                  "internalTrafficPolicy is local with zero local endpoints",
+			internalTrafficPolicy: &local,
+			endpoints: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: false},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+				&BaseEndpointInfo{Endpoint: "10.0.0.2:80", IsLocal: false},
+			},
+			expected:      nil,
+			featureGateOn: true,
+		},
+		{
+			name:                  "feature gate is off, internalTrafficPolicy is local with non-empty endpoints",
+			internalTrafficPolicy: &local,
+			endpoints: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+				&BaseEndpointInfo{Endpoint: "10.0.0.2:80", IsLocal: false},
+			},
+			expected: []Endpoint{
+				&BaseEndpointInfo{Endpoint: "10.0.0.0:80", IsLocal: true},
+				&BaseEndpointInfo{Endpoint: "10.0.0.1:80", IsLocal: false},
+				&BaseEndpointInfo{Endpoint: "10.0.0.2:80", IsLocal: false},
+			},
+			featureGateOn: false,
+		},
+	}
+	for _, tc := range testCases {
+		defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceInternalTrafficPolicy, tc.featureGateOn)()
+		t.Run(tc.name, func(t *testing.T) {
+			filteredEndpoint := FilterLocalEndpoint(tc.internalTrafficPolicy, tc.endpoints)
+			if !reflect.DeepEqual(filteredEndpoint, tc.expected) {
+				t.Errorf("expected %v, got %v", tc.expected, filteredEndpoint)
+			}
+		})
+	}
+}

pkg/proxy/types.go

@@ -85,6 +85,10 @@ type ServicePort interface {
 	NodePort() int
 	// GetOnlyNodeLocalEndpoints returns if a service has only node local endpoints
 	OnlyNodeLocalEndpoints() bool
+	// OnlyNodeLocalEndpointsForInternal returns if a service prefers routing to node local endpoints for internal traffic
+	OnlyNodeLocalEndpointsForInternal() bool
+	// InternalTrafficPolicy returns service InternalTrafficPolicy
+	InternalTrafficPolicy() *v1.ServiceInternalTrafficPolicyType
 	// TopologyKeys returns service TopologyKeys as a string array.
 	TopologyKeys() []string
 }

pkg/registry/core/service/strategy.go

@@ -156,7 +156,7 @@ func dropServiceDisabledFields(newSvc *api.Service, oldSvc *api.Service) {
 		newSvc.Spec.TopologyKeys = nil
 	}
 
-	// Clear AllocateLoadBalancerNodePorts if ServiceLBNodePortControl if not enabled
+	// Clear AllocateLoadBalancerNodePorts if ServiceLBNodePortControl is not enabled
 	if !utilfeature.DefaultFeatureGate.Enabled(features.ServiceLBNodePortControl) {
 		if !allocateLoadBalancerNodePortsInUse(oldSvc) {
 			newSvc.Spec.AllocateLoadBalancerNodePorts = nil
@@ -180,6 +180,13 @@ func dropServiceDisabledFields(newSvc *api.Service, oldSvc *api.Service) {
 			newSvc.Spec.LoadBalancerClass = nil
 		}
 	}
+
+	// Clear InternalTrafficPolicy if not enabled
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ServiceInternalTrafficPolicy) {
+		if !serviceInternalTrafficPolicyInUse(oldSvc) {
+			newSvc.Spec.InternalTrafficPolicy = nil
+		}
+	}
 }
 
 // returns true if svc.Spec.AllocateLoadBalancerNodePorts field is in use
@@ -240,6 +247,13 @@ func loadBalancerClassInUse(svc *api.Service) bool {
 	return svc.Spec.LoadBalancerClass != nil
 }
 
+func serviceInternalTrafficPolicyInUse(svc *api.Service) bool {
+	if svc == nil {
+		return false
+	}
+	return svc.Spec.InternalTrafficPolicy != nil
+}
+
 type serviceStatusStrategy struct {
 	Strategy
 }

pkg/registry/core/service/strategy_test.go

@@ -257,19 +257,30 @@ func makeServiceWithLoadBalancerClass(loadBalancerClass *string) *api.Service {
 	}
 }
 
+func makeServiceWithInternalTrafficPolicy(policy *api.ServiceInternalTrafficPolicyType) *api.Service {
+	return &api.Service{
+		Spec: api.ServiceSpec{
+			InternalTrafficPolicy: policy,
+		},
+	}
+}
+
 func TestDropDisabledField(t *testing.T) {
 	requireDualStack := api.IPFamilyPolicyRequireDualStack
 	preferDualStack := api.IPFamilyPolicyPreferDualStack
 	singleStack := api.IPFamilyPolicySingleStack
 
+	localInternalTrafficPolicy := api.ServiceInternalTrafficPolicyLocal
+
 	testCases := []struct {
-		name                    string
-		enableDualStack         bool
-		enableMixedProtocol     bool
-		enableLoadBalancerClass bool
-		svc                     *api.Service
-		oldSvc                  *api.Service
-		compareSvc              *api.Service
+		name                        string
+		enableDualStack             bool
+		enableMixedProtocol         bool
+		enableLoadBalancerClass     bool
+		enableInternalTrafficPolicy bool
+		svc                         *api.Service
+		oldSvc                      *api.Service
+		compareSvc                  *api.Service
 	}{
 		{
 			name:            "not dual stack, field not used",
@@ -500,6 +511,28 @@ func TestDropDisabledField(t *testing.T) {
 			oldSvc:                  makeServiceWithLoadBalancerClass(utilpointer.StringPtr("test.com/test")),
 			compareSvc:              makeServiceWithLoadBalancerClass(nil),
 		},
+		/* svc.spec.internalTrafficPolicy */
+		{
+			name:                        "internal traffic policy not enabled, field used in old, not used in new",
+			enableInternalTrafficPolicy: false,
+			svc:                         makeServiceWithInternalTrafficPolicy(nil),
+			oldSvc:                      makeServiceWithInternalTrafficPolicy(&localInternalTrafficPolicy),
+			compareSvc:                  makeServiceWithInternalTrafficPolicy(nil),
+		},
+		{
+			name:                        "internal traffic policy not enabled, field not used in old, used in new",
+			enableInternalTrafficPolicy: false,
+			svc:                         makeServiceWithInternalTrafficPolicy(&localInternalTrafficPolicy),
+			oldSvc:                      makeServiceWithInternalTrafficPolicy(nil),
+			compareSvc:                  makeServiceWithInternalTrafficPolicy(nil),
+		},
+		{
+			name:                        "internal traffic policy enabled, field not used in old, used in new",
+			enableInternalTrafficPolicy: true,
+			svc:                         makeServiceWithInternalTrafficPolicy(&localInternalTrafficPolicy),
+			oldSvc:                      makeServiceWithInternalTrafficPolicy(nil),
+			compareSvc:                  makeServiceWithInternalTrafficPolicy(&localInternalTrafficPolicy),
+		},
 		/* add more tests for other dropped fields as needed */
 	}
 	for _, tc := range testCases {
@@ -507,12 +540,13 @@ func TestDropDisabledField(t *testing.T) {
 			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.IPv6DualStack, tc.enableDualStack)()
 			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.MixedProtocolLBService, tc.enableMixedProtocol)()
 			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceLoadBalancerClass, tc.enableLoadBalancerClass)()
+			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceInternalTrafficPolicy, tc.enableInternalTrafficPolicy)()
 			old := tc.oldSvc.DeepCopy()
 
 			// to test against user using IPFamily not set on cluster
 			dropServiceDisabledFields(tc.svc, tc.oldSvc)
 
-			// old node  should never be changed
+			// old node should never be changed
 			if !reflect.DeepEqual(tc.oldSvc, old) {
 				t.Errorf("%v: old svc changed: %v", tc.name, diff.ObjectReflectDiff(tc.oldSvc, old))
 			}

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

@@ -3940,6 +3940,19 @@ const (
 	ServiceTypeExternalName ServiceType = "ExternalName"
 )
 
+// ServiceInternalTrafficPolicyType describes the type of traffic routing for
+// internal traffic
+type ServiceInternalTrafficPolicyType string
+
+const (
+	// ServiceInternalTrafficPolicyCluster routes traffic to all endpoints
+	ServiceInternalTrafficPolicyCluster ServiceInternalTrafficPolicyType = "Cluster"
+
+	// ServiceInternalTrafficPolicyLocal only routes to node-local
+	// endpoints, otherwise drops the traffic
+	ServiceInternalTrafficPolicyLocal ServiceInternalTrafficPolicyType = "Local"
+)
+
 // Service External Traffic Policy Type string
 type ServiceExternalTrafficPolicyType string
 
@@ -4272,9 +4285,19 @@ type ServiceSpec struct {
 	// implementation (e.g. cloud providers) should ignore Services that set this field.
 	// This field can only be set when creating or updating a Service to type 'LoadBalancer'.
 	// Once set, it can not be changed. This field will be wiped when a service is updated to a non 'LoadBalancer' type.
-	// featureGate=LoadBalancerClass
+	// +featureGate=LoadBalancerClass
 	// +optional
 	LoadBalancerClass *string `json:"loadBalancerClass,omitempty" protobuf:"bytes,21,opt,name=loadBalancerClass"`
+
+	// InternalTrafficPolicy specifies if the cluster internal traffic
+	// should be routed to all endpoints or node-local endpoints only.
+	// "Cluster" routes internal traffic to a Service to all endpoints.
+	// "Local" routes traffic to node-local endpoints only, traffic is
+	// dropped if no node-local endpoints are ready.
+	// The default value is "Cluster".
+	// +featureGate=ServiceInternalTrafficPolicy
+	// +optional
+	InternalTrafficPolicy *ServiceInternalTrafficPolicyType `json:"internalTrafficPolicy,omitempty" protobuf:"bytes,22,opt,name=internalTrafficPolicy"`
 }
 
 // ServicePort contains information on service's port.

staging/src/k8s.io/api/core/v1/types_swagger_doc_generated.go

@@ -2258,6 +2258,7 @@ var map_ServiceSpec = map[string]string{
 	"ipFamilyPolicy":                "IPFamilyPolicy represents the dual-stack-ness requested or required by this Service, and is gated by the \"IPv6DualStack\" feature gate.  If there is no value provided, then this field will be set to SingleStack. Services can be \"SingleStack\" (a single IP family), \"PreferDualStack\" (two IP families on dual-stack configured clusters or a single IP family on single-stack clusters), or \"RequireDualStack\" (two IP families on dual-stack configured clusters, otherwise fail). The ipFamilies and clusterIPs fields depend on the value of this field.  This field will be wiped when updating a service to type ExternalName.",
 	"allocateLoadBalancerNodePorts": "allocateLoadBalancerNodePorts defines if NodePorts will be automatically allocated for services with type LoadBalancer.  Default is \"true\". It may be set to \"false\" if the cluster load-balancer does not rely on NodePorts. allocateLoadBalancerNodePorts may only be set for services with type LoadBalancer and will be cleared if the type is changed to any other type. This field is alpha-level and is only honored by servers that enable the ServiceLBNodePortControl feature.",
 	"loadBalancerClass":             "loadBalancerClass is the class of the load balancer implementation this Service belongs to. If specified, the value of this field must be a label-style identifier, with an optional prefix, e.g. \"internal-vip\" or \"example.com/internal-vip\". Unprefixed names are reserved for end-users. This field can only be set when the Service type is 'LoadBalancer'. If not set, the default load balancer implementation is used, today this is typically done through the cloud provider integration, but should apply for any default implementation. If set, it is assumed that a load balancer implementation is watching for Services with a matching class. Any default load balancer implementation (e.g. cloud providers) should ignore Services that set this field. This field can only be set when creating or updating a Service to type 'LoadBalancer'. Once set, it can not be changed. This field will be wiped when a service is updated to a non 'LoadBalancer' type. featureGate=LoadBalancerClass",
+	"internalTrafficPolicy":         "InternalTrafficPolicy specifies if the cluster internal traffic should be routed to all endpoints or node-local endpoints only. \"Cluster\" routes internal traffic to a Service to all endpoints. \"Local\" routes traffic to node-local endpoints only, traffic is dropped if no node-local endpoints are ready. featureGate=ServiceInternalTrafficPolicy",
 }
 
 func (ServiceSpec) SwaggerDoc() map[string]string {

staging/src/k8s.io/api/core/v1/zz_generated.deepcopy.go

@@ -5350,6 +5350,11 @@ func (in *ServiceSpec) DeepCopyInto(out *ServiceSpec) {
 		*out = new(string)
 		**out = **in
 	}
+	if in.InternalTrafficPolicy != nil {
+		in, out := &in.InternalTrafficPolicy, &out.InternalTrafficPolicy
+		*out = new(ServiceInternalTrafficPolicyType)
+		**out = **in
+	}
 	return
 }
 

staging/src/k8s.io/api/testdata/HEAD/core.v1.Service.json

@@ -84,7 +84,8 @@
     ],
     "ipFamilyPolicy": "9ȫŚ",
     "allocateLoadBalancerNodePorts": true,
-    "loadBalancerClass": "31"
+    "loadBalancerClass": "31",
+    "internalTrafficPolicy": ""
   },
   "status": {
     "loadBalancer": {
@@ -94,8 +95,8 @@
           "hostname": "33",
           "ports": [
             {
-              "port": -907310967,
-              "protocol": "喂ƈ斎AO6",
+              "port": 684408190,
+              "protocol": "ƈ斎AO6ĴC浔Ű",
               "error": "34"
             }
           ]
@@ -105,9 +106,9 @@
     "conditions": [
       {
         "type": "35",
-        "status": "C",
-        "observedGeneration": -2492120148461555858,
-        "lastTransitionTime": "2392-12-09T15:37:55Z",
+        "status": "ž(-譵",
+        "observedGeneration": -8651056334266075769,
+        "lastTransitionTime": "2404-01-10T11:35:42Z",
         "reason": "36",
         "message": "37"
       }

staging/src/k8s.io/api/testdata/HEAD/core.v1.Service.yaml

@@ -39,6 +39,7 @@ spec:
   externalName: "29"
   externalTrafficPolicy: ƏS$+½H牗洝尿
   healthCheckNodePort: -1965738697
+  internalTrafficPolicy: ""
   ipFamilies:
   - 斬³;Ơ歿:狞夌碕ʂɭîcP$Iņɖ
   ipFamilyPolicy: 9ȫŚ
@@ -65,11 +66,11 @@ spec:
   type: 鮽ort昍řČ扷5ƗǸƢ6/ʕVŚ(Ŀ
 status:
   conditions:
-  - lastTransitionTime: "2392-12-09T15:37:55Z"
+  - lastTransitionTime: "2404-01-10T11:35:42Z"
     message: "37"
-    observedGeneration: -2492120148461555858
+    observedGeneration: -8651056334266075769
     reason: "36"
-    status: C
+    status: ž(-譵
     type: "35"
   loadBalancer:
     ingress:
@@ -77,5 +78,5 @@ status:
       ip: "32"
       ports:
       - error: "34"
-        port: -907310967
-        protocol: 喂ƈ斎AO6
+        port: 684408190
+        protocol: ƈ斎AO6ĴC浔Ű

staging/src/k8s.io/client-go/applyconfigurations/core/v1/servicespec.go

@@ -44,6 +44,7 @@ type ServiceSpecApplyConfiguration struct {
 	IPFamilyPolicy                *corev1.IPFamilyPolicyType               `json:"ipFamilyPolicy,omitempty"`
 	AllocateLoadBalancerNodePorts *bool                                    `json:"allocateLoadBalancerNodePorts,omitempty"`
 	LoadBalancerClass             *string                                  `json:"loadBalancerClass,omitempty"`
+	InternalTrafficPolicy         *corev1.ServiceInternalTrafficPolicyType `json:"internalTrafficPolicy,omitempty"`
 }
 
 // ServiceSpecApplyConfiguration constructs an declarative configuration of the ServiceSpec type for use with
@@ -224,3 +225,11 @@ func (b *ServiceSpecApplyConfiguration) WithLoadBalancerClass(value string) *Ser
 	b.LoadBalancerClass = &value
 	return b
 }
+
+// WithInternalTrafficPolicy sets the InternalTrafficPolicy field in the declarative configuration to the given value
+// and returns the receiver, so that objects can be built by chaining "With" function invocations.
+// If called multiple times, the InternalTrafficPolicy field is set to the value of the last call.
+func (b *ServiceSpecApplyConfiguration) WithInternalTrafficPolicy(value corev1.ServiceInternalTrafficPolicyType) *ServiceSpecApplyConfiguration {
+	b.InternalTrafficPolicy = &value
+	return b
+}