Remove usage of ServiceTrafficDistribution feature-gate from kube-proxy packages.

ServiceTrafficDistribution feature-gate is GA'd and enabled by default since
1.33. Since it is also locked-to-default, we can remove flag-usages in
kube-proxy.

NOTE that as per
https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/feature-gates.md#disablement-tests:
_"Disablement tests are only required to be preserved for components and
libraries that support compatibility version. Tests for node and kubelet are
unaffected by compatibility version."_

pkg/proxy/topology.go

@@ -18,9 +18,7 @@ package proxy
 
 import (
 	v1 "k8s.io/api/core/v1"
-	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/klog/v2"
-	"k8s.io/kubernetes/pkg/features"
 )
 
 // CategorizeEndpoints returns:
@@ -41,7 +39,7 @@ func CategorizeEndpoints(endpoints []Endpoint, svcInfo ServicePort, nodeLabels m
 	var useTopology, useServingTerminatingEndpoints bool
 
 	if svcInfo.UsesClusterEndpoints() {
-		useTopology = canUseTopology(endpoints, svcInfo, nodeLabels)
+		useTopology = canUseTopology(endpoints, nodeLabels)
 		clusterEndpoints = filterEndpoints(endpoints, func(ep Endpoint) bool {
 			if !ep.IsReady() {
 				return false
@@ -137,29 +135,11 @@ func CategorizeEndpoints(endpoints []Endpoint, svcInfo ServicePort, nodeLabels m
 	return
 }
 
-// canUseTopology returns true if topology aware routing is enabled and properly
+// canUseTopology returns true if all of the following is true:
-// configured in this cluster. That is, it checks that:
-//   - The TopologyAwareHints or ServiceTrafficDistribution feature is enabled.
-//   - If ServiceTrafficDistribution feature gate is not enabled, then the
-//     hintsAnnotation should represent an enabled value.
 //   - The node's labels include "topology.kubernetes.io/zone".
 //   - All of the endpoints for this Service have a topology hint.
 //   - At least one endpoint for this Service is hinted for this node's zone.
-func canUseTopology(endpoints []Endpoint, svcInfo ServicePort, nodeLabels map[string]string) bool {
+func canUseTopology(endpoints []Endpoint, nodeLabels map[string]string) bool {
-	if !utilfeature.DefaultFeatureGate.Enabled(features.TopologyAwareHints) && !utilfeature.DefaultFeatureGate.Enabled(features.ServiceTrafficDistribution) {
-		return false
-	}
-
-	// Ignore value of hintsAnnotation if the ServiceTrafficDistribution feature
-	// gate is enabled.
-	if !utilfeature.DefaultFeatureGate.Enabled(features.ServiceTrafficDistribution) {
-		// If the hintsAnnotation has a disabled value, we do not consider hints for route programming.
-		hintsAnnotation := svcInfo.HintsAnnotation()
-		if hintsAnnotation == "" || hintsAnnotation == "disabled" || hintsAnnotation == "Disabled" {
-			return false
-		}
-	}
-
 	zone, foundZone := nodeLabels[v1.LabelTopologyZone]
 	hasEndpointForZone := false
 	for _, endpoint := range endpoints {

pkg/proxy/topology_test.go

@@ -49,7 +49,6 @@ func TestCategorizeEndpoints(t *testing.T) {
 	testCases := []struct {
 		name         string
 		hintsEnabled bool
-		trafficDistFeatureEnabled bool
 		pteEnabled   bool
 		nodeLabels   map[string]string
 		serviceInfo  ServicePort
@@ -79,7 +78,7 @@ func TestCategorizeEndpoints(t *testing.T) {
 		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.6:80"),
 		localEndpoints:   nil,
 	}, {
-		name:         "hints, hints annotation == disabled, hints ignored",
+		name:         "hints, hints annotation == disabled, but endpointslice hints are not ignored since trafficDist feature-gate is always enabled by default",
 		hintsEnabled: true,
 		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
 		serviceInfo:  &BaseServicePortInfo{hintsAnnotation: "disabled"},
@@ -89,20 +88,7 @@ func TestCategorizeEndpoints(t *testing.T) {
 			&BaseEndpointInfo{endpoint: "10.1.2.5:80", zoneHints: sets.New[string]("zone-c"), ready: true},
 			&BaseEndpointInfo{endpoint: "10.1.2.6:80", zoneHints: sets.New[string]("zone-a"), ready: true},
 		},
-		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.4:80", "10.1.2.5:80", "10.1.2.6:80"),
+		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.6:80"),
-		localEndpoints:   nil,
-	}, {
-		name:         "hints disabled, hints annotation == auto",
-		hintsEnabled: false,
-		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
-		serviceInfo:  &BaseServicePortInfo{hintsAnnotation: "auto"},
-		endpoints: []Endpoint{
-			&BaseEndpointInfo{endpoint: "10.1.2.3:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.4:80", zoneHints: sets.New[string]("zone-b"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.5:80", zoneHints: sets.New[string]("zone-c"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.6:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-		},
-		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.4:80", "10.1.2.5:80", "10.1.2.6:80"),
 		localEndpoints:   nil,
 	}, {
 
@@ -119,24 +105,10 @@ func TestCategorizeEndpoints(t *testing.T) {
 		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.6:80"),
 		localEndpoints:   nil,
 	}, {
-		name:         "hints, hints annotation empty, hints ignored",
+		name:         "hints, hints annotation empty but endpointslice hints are not ignored since trafficDist feature-gate is always enabled by default",
 		hintsEnabled: true,
 		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
-		serviceInfo:  &BaseServicePortInfo{},
+		serviceInfo:  &BaseServicePortInfo{ /* hints annotation empty */ },
-		endpoints: []Endpoint{
-			&BaseEndpointInfo{endpoint: "10.1.2.3:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.4:80", zoneHints: sets.New[string]("zone-b"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.5:80", zoneHints: sets.New[string]("zone-c"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.6:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-		},
-		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.4:80", "10.1.2.5:80", "10.1.2.6:80"),
-		localEndpoints:   nil,
-	}, {
-		name:                      "hints, hints annotation empty but trafficDist feature gate enabled, hints are not ignored",
-		hintsEnabled:              true,
-		trafficDistFeatureEnabled: true,
-		nodeLabels:                map[string]string{v1.LabelTopologyZone: "zone-a"},
-		serviceInfo:               &BaseServicePortInfo{},
 		endpoints: []Endpoint{
 			&BaseEndpointInfo{endpoint: "10.1.2.3:80", zoneHints: sets.New[string]("zone-a"), ready: true},
 			&BaseEndpointInfo{endpoint: "10.1.2.4:80", zoneHints: sets.New[string]("zone-b"), ready: true},
@@ -146,9 +118,8 @@ func TestCategorizeEndpoints(t *testing.T) {
 		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.6:80"),
 		localEndpoints:   nil,
 	}, {
-		name:                      "hints disabled, trafficDist feature gate enabled, hints are not ignored",
+		name:         "hints feature-gate disabled but endpointslice hints are not ignored since trafficDist feature-gate is always enabled by default",
 		hintsEnabled: false,
-		trafficDistFeatureEnabled: true,
 		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
 		serviceInfo:  &BaseServicePortInfo{},
 		endpoints: []Endpoint{
@@ -162,7 +133,6 @@ func TestCategorizeEndpoints(t *testing.T) {
 	}, {
 		name:         "externalTrafficPolicy: Local, topology ignored for Local endpoints",
 		hintsEnabled: true,
-		trafficDistFeatureEnabled: true,
 		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
 		serviceInfo:  &BaseServicePortInfo{externalPolicyLocal: true, nodePort: 8080, hintsAnnotation: "auto"},
 		endpoints: []Endpoint{
@@ -177,7 +147,6 @@ func TestCategorizeEndpoints(t *testing.T) {
 	}, {
 		name:         "internalTrafficPolicy: Local, topology ignored for Local endpoints",
 		hintsEnabled: true,
-		trafficDistFeatureEnabled: true,
 		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
 		serviceInfo:  &BaseServicePortInfo{internalPolicyLocal: true, hintsAnnotation: "auto", externalPolicyLocal: false, nodePort: 8080},
 		endpoints: []Endpoint{
@@ -271,32 +240,6 @@ func TestCategorizeEndpoints(t *testing.T) {
 		},
 		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.6:80"),
 		localEndpoints:   nil,
-	}, {
-		name:         "hintsAnnotation empty, no filtering applied",
-		hintsEnabled: true,
-		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
-		serviceInfo:  &BaseServicePortInfo{hintsAnnotation: ""},
-		endpoints: []Endpoint{
-			&BaseEndpointInfo{endpoint: "10.1.2.3:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.4:80", zoneHints: sets.New[string]("zone-b"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.5:80", zoneHints: sets.New[string]("zone-c"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.6:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-		},
-		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.4:80", "10.1.2.5:80", "10.1.2.6:80"),
-		localEndpoints:   nil,
-	}, {
-		name:         "hintsAnnotation disabled, no filtering applied",
-		hintsEnabled: true,
-		nodeLabels:   map[string]string{v1.LabelTopologyZone: "zone-a"},
-		serviceInfo:  &BaseServicePortInfo{hintsAnnotation: "disabled"},
-		endpoints: []Endpoint{
-			&BaseEndpointInfo{endpoint: "10.1.2.3:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.4:80", zoneHints: sets.New[string]("zone-b"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.5:80", zoneHints: sets.New[string]("zone-c"), ready: true},
-			&BaseEndpointInfo{endpoint: "10.1.2.6:80", zoneHints: sets.New[string]("zone-a"), ready: true},
-		},
-		clusterEndpoints: sets.New[string]("10.1.2.3:80", "10.1.2.4:80", "10.1.2.5:80", "10.1.2.6:80"),
-		localEndpoints:   nil,
 	}, {
 		name:         "missing hints, no filtering applied",
 		hintsEnabled: true,
@@ -489,7 +432,6 @@ func TestCategorizeEndpoints(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.TopologyAwareHints, tc.hintsEnabled)
-			featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ServiceTrafficDistribution, tc.trafficDistFeatureEnabled)
 
 			clusterEndpoints, localEndpoints, allEndpoints, hasAnyEndpoints := CategorizeEndpoints(tc.endpoints, tc.serviceInfo, tc.nodeLabels)