perf(source): benchmarks on EndpointTargetsFromServices (#5536)

* chore(benchmarking): added benchmarks to EndpointTargetsFromServices

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

* chore(benchmarking): added benchmarks to EndpointTargetsFromServices

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

* chore(benchmarking): added benchmarks to EndpointTargetsFromServices

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

* chore(benchmarking): added benchmarks to EndpointTargetsFromServices

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

---------

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

source/endpoint_benchmark_test.go

@@ -0,0 +1,233 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package source
+
+import (
+	"context"
+	"encoding/binary"
+	"fmt"
+	"math/rand/v2"
+	"net"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	kubeinformers "k8s.io/client-go/informers"
+	coreinformers "k8s.io/client-go/informers/core/v1"
+	"k8s.io/client-go/kubernetes/fake"
+
+	v1alpha3 "istio.io/api/networking/v1alpha3"
+	istiov1a "istio.io/client-go/pkg/apis/networking/v1"
+
+	"k8s.io/client-go/tools/cache"
+)
+
+func BenchmarkEndpointTargetsFromServicesMedium(b *testing.B) {
+	svcInformer, err := svcInformerWithServices(36, 1000)
+	assert.NoError(b, err)
+
+	sel := map[string]string{"app": "nginx", "env": "prod"}
+
+	for b.Loop() {
+		targets, _ := EndpointTargetsFromServices(svcInformer, "default", sel)
+		assert.Equal(b, 36, targets.Len())
+	}
+}
+
+func BenchmarkEndpointTargetsFromServicesMediumIterateOverGateways(b *testing.B) {
+	svcInformer, err := svcInformerWithServices(36, 500)
+	assert.NoError(b, err)
+
+	gateways := fixturesIstioGatewaySvcWithLabels(15, 70)
+
+	for b.Loop() {
+		for _, gateway := range gateways {
+			_, _ = EndpointTargetsFromServices(svcInformer, gateway.Namespace, gateway.Spec.Selector)
+		}
+	}
+}
+
+func BenchmarkEndpointTargetsFromServicesHigh(b *testing.B) {
+	svcInformer, err := svcInformerWithServices(36, 40000)
+	assert.NoError(b, err)
+	sel := map[string]string{"app": "nginx", "env": "prod"}
+
+	for b.Loop() {
+		targets, _ := EndpointTargetsFromServices(svcInformer, "default", sel)
+		assert.Equal(b, 36, targets.Len())
+	}
+}
+
+// This benchmark tests the performance of EndpointTargetsFromServices with a high number of services and gateways.
+func BenchmarkEndpointTargetsFromServicesHighIterateOverGateways(b *testing.B) {
+	svcInformer, err := svcInformerWithServices(36, 40000)
+	assert.NoError(b, err)
+
+	gateways := fixturesIstioGatewaySvcWithLabels(50, 1000)
+
+	for b.Loop() {
+		for _, gateway := range gateways {
+			_, _ = EndpointTargetsFromServices(svcInformer, gateway.Namespace, gateway.Spec.Selector)
+		}
+	}
+}
+
+// helperToPopulateFakeClientWithServices populates a fake Kubernetes client with a specified services.
+func svcInformerWithServices(toLookup, underTest int) (coreinformers.ServiceInformer, error) {
+	client := fake.NewClientset()
+	informerFactory := kubeinformers.NewSharedInformerFactoryWithOptions(client, 0, kubeinformers.WithNamespace("default"))
+	svcInformer := informerFactory.Core().V1().Services()
+	ctx := context.Background()
+
+	_, err := svcInformer.Informer().AddEventHandler(
+		cache.ResourceEventHandlerFuncs{
+			AddFunc: func(obj interface{}) {
+			},
+		},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to add event handler: %w", err)
+	}
+
+	services := fixturesSvcWithLabels(toLookup, underTest)
+	for _, svc := range services {
+		_, err := client.CoreV1().Services(svc.Namespace).Create(ctx, svc, metav1.CreateOptions{})
+		if err != nil {
+			return nil, fmt.Errorf("failed to create service %s: %w", svc.Name, err)
+		}
+	}
+
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+	informerFactory.Start(stopCh)
+	cache.WaitForCacheSync(stopCh, svcInformer.Informer().HasSynced)
+	return svcInformer, nil
+}
+
+// fixturesSvcWithLabels creates a list of Services for testing purposes.
+// It generates a specified number of services with static labels and random labels.
+// The first `toLookup` services have specific labels, while the next `underTest` services have random labels.
+func fixturesSvcWithLabels(toLookup, underTest int) []*corev1.Service {
+	var services []*corev1.Service
+
+	var randomLabels = func(input int) map[string]string {
+		if input%3 == 0 {
+			// every third service has no labels
+			return map[string]string{}
+		}
+		return map[string]string{
+			"app":                                fmt.Sprintf("service-%d", rand.IntN(100)),
+			fmt.Sprintf("key%d", rand.IntN(100)): fmt.Sprintf("value%d", rand.IntN(100)),
+		}
+	}
+
+	var randomIPs = func() []string {
+		ip := rand.Uint32()
+		buf := make([]byte, 4)
+		binary.LittleEndian.PutUint32(buf, ip)
+		return []string{net.IP(buf).String()}
+	}
+
+	var createService = func(name string, namespace string, selector map[string]string) *corev1.Service {
+		return &corev1.Service{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      name,
+				Namespace: namespace,
+			},
+			Spec: corev1.ServiceSpec{
+				Selector:    selector,
+				ExternalIPs: randomIPs(),
+			},
+		}
+	}
+
+	// services with specific labels
+	for i := 0; i < toLookup; i++ {
+		svc := createService("nginx-svc-"+strconv.Itoa(i), "default", map[string]string{"app": "nginx", "env": "prod"})
+		services = append(services, svc)
+	}
+
+	// services with random labels
+	for i := 0; i < underTest; i++ {
+		svc := createService("random-svc-"+strconv.Itoa(i), "default", randomLabels(i))
+		services = append(services, svc)
+	}
+
+	// Shuffle the services to ensure randomness
+	for i := 0; i < 3; i++ {
+		rand.Shuffle(len(services), func(i, j int) {
+			services[i], services[j] = services[j], services[i]
+		})
+	}
+
+	return services
+}
+
+// fixturesIstioGatewaySvcWithLabels creates a list of Services for testing purposes.
+// It generates a specified number of gateways with static labels and random labels.
+// The first `toLookup` services have specific labels, while the next `underTest` services have random labels.
+func fixturesIstioGatewaySvcWithLabels(toLookup, underTest int) []*istiov1a.Gateway {
+	var result []*istiov1a.Gateway
+
+	var randomLabels = func(input int) map[string]string {
+		if input%3 == 0 {
+			// every third service has no labels
+			return map[string]string{}
+		}
+		return map[string]string{
+			"app":                                fmt.Sprintf("service-%d", rand.IntN(100)),
+			fmt.Sprintf("key%d", rand.IntN(100)): fmt.Sprintf("value%d", rand.IntN(100)),
+		}
+	}
+
+	var createGateway = func(name string, namespace string, selector map[string]string) *istiov1a.Gateway {
+		return &istiov1a.Gateway{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      name,
+				Namespace: namespace,
+			},
+			Spec: v1alpha3.Gateway{
+				Selector: selector,
+				Servers: []*v1alpha3.Server{
+					{
+						Port:  &v1alpha3.Port{},
+						Hosts: []string{"*"},
+					},
+				},
+			},
+		}
+	}
+	// services with specific labels
+	for i := 0; i < toLookup; i++ {
+		svc := createGateway("istio-gw-"+strconv.Itoa(i), "default", map[string]string{"app": "nginx", "env": "prod"})
+		result = append(result, svc)
+	}
+
+	// services with random labels
+	for i := 0; i < underTest; i++ {
+		svc := createGateway("istio-random-svc-"+strconv.Itoa(i), "default", randomLabels(i))
+		result = append(result, svc)
+	}
+
+	// Shuffle the services to ensure randomness
+	for i := 0; i < 3; i++ {
+		rand.Shuffle(len(result), func(i, j int) {
+			result[i], result[j] = result[j], result[i]
+		})
+	}
+
+	return result
+}

source/endpoints.go

@@ -85,6 +85,7 @@ func EndpointTargetsFromServices(svcInformer coreinformers.ServiceInformer, name
 	targets := endpoint.Targets{}
 
 	services, err := svcInformer.Lister().Services(namespace).List(labels.Everything())
+
 	if err != nil {
 		return nil, fmt.Errorf("failed to list labels for services in namespace %q: %w", namespace, err)
 	}

source/endpoints_test.go

@@ -22,6 +22,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	kubeinformers "k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes/fake"
+
 	"sigs.k8s.io/external-dns/endpoint"
 )
 
@@ -137,7 +138,6 @@ func TestEndpointTargetsFromServices(t *testing.T) {
 			namespace: "default",
 			selector:  map[string]string{"app": "nginx"},
 			expected:  endpoint.Targets{},
-			wantErr:   false,
 		},
 		{
 			name: "matching service with external IPs",
@@ -156,7 +156,23 @@ func TestEndpointTargetsFromServices(t *testing.T) {
 			namespace: "default",
 			selector:  map[string]string{"app": "nginx"},
 			expected:  endpoint.Targets{"192.0.2.1", "158.123.32.23"},
-			wantErr:   false,
+		},
+		{
+			name: "no matching service as service without selector",
+			services: []*corev1.Service{
+				{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "svc1",
+						Namespace: "default",
+					},
+					Spec: corev1.ServiceSpec{
+						ExternalIPs: []string{"192.0.2.1"},
+					},
+				},
+			},
+			namespace: "default",
+			selector:  map[string]string{"app": "nginx"},
+			expected:  endpoint.Targets{},
 		},
 		{
 			name: "matching service with load balancer IP",
@@ -181,7 +197,6 @@ func TestEndpointTargetsFromServices(t *testing.T) {
 			namespace: "default",
 			selector:  map[string]string{"app": "nginx"},
 			expected:  endpoint.Targets{"192.0.2.2"},
-			wantErr:   false,
 		},
 		{
 			name: "matching service with load balancer hostname",
@@ -206,7 +221,6 @@ func TestEndpointTargetsFromServices(t *testing.T) {
 			namespace: "default",
 			selector:  map[string]string{"app": "nginx"},
 			expected:  endpoint.Targets{"lb.example.com"},
-			wantErr:   false,
 		},
 		{
 			name: "no matching services",
@@ -224,13 +238,12 @@ func TestEndpointTargetsFromServices(t *testing.T) {
 			namespace: "default",
 			selector:  map[string]string{"app": "nginx"},
 			expected:  endpoint.Targets{},
-			wantErr:   false,
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			client := fake.NewSimpleClientset()
+			client := fake.NewClientset()
 			informerFactory := kubeinformers.NewSharedInformerFactoryWithOptions(client, 0,
 				kubeinformers.WithNamespace(tt.namespace))
 			serviceInformer := informerFactory.Core().V1().Services()
@@ -253,3 +266,14 @@ func TestEndpointTargetsFromServices(t *testing.T) {
 		})
 	}
 }
+
+func TestEndpointTargetsFromServicesWithFixtures(t *testing.T) {
+	svcInformer, err := svcInformerWithServices(2, 9)
+	assert.NoError(t, err)
+
+	sel := map[string]string{"app": "nginx", "env": "prod"}
+
+	targets, err := EndpointTargetsFromServices(svcInformer, "default", sel)
+	assert.NoError(t, err)
+	assert.Equal(t, 2, targets.Len())
+}

source/f5_virtualserver_test.go

@@ -329,7 +329,7 @@ func TestF5VirtualServerEndpoints(t *testing.T) {
 
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			fakeKubernetesClient := fakeKube.NewSimpleClientset()
+			fakeKubernetesClient := fakeKube.NewClientset()
 			scheme := runtime.NewScheme()
 			scheme.AddKnownTypes(f5VirtualServerGVR.GroupVersion(), &f5.VirtualServer{}, &f5.VirtualServerList{})
 			fakeDynamicClient := fakeDynamic.NewSimpleDynamicClient(scheme)

source/istio_gateway.go

@@ -260,13 +260,7 @@ func (sc *gatewaySource) targetsFromGateway(ctx context.Context, gateway *networ
 		return sc.targetsFromIngress(ctx, ingressStr, gateway)
 	}
 
-	targets, err := EndpointTargetsFromServices(sc.serviceInformer, sc.namespace, gateway.Spec.Selector)
+	return EndpointTargetsFromServices(sc.serviceInformer, sc.namespace, gateway.Spec.Selector)
-
-	if err != nil {
-		return nil, err
-	}
-
-	return targets, nil
 }
 
 // endpointsFromGatewayConfig extracts the endpoints from an Istio Gateway Config object
@@ -323,12 +317,3 @@ func (sc *gatewaySource) hostNamesFromGateway(gateway *networkingv1alpha3.Gatewa
 
 	return hostnames, nil
 }
-
-func gatewaySelectorMatchesServiceSelector(gwSelector, svcSelector map[string]string) bool {
-	for k, v := range gwSelector {
-		if lbl, ok := svcSelector[k]; !ok || lbl != v {
-			return false
-		}
-	}
-	return true
-}

source/istio_gateway_test.go

@@ -46,7 +46,7 @@ type GatewaySuite struct {
 }
 
 func (suite *GatewaySuite) SetupTest() {
-	fakeKubernetesClient := fake.NewSimpleClientset()
+	fakeKubernetesClient := fake.NewClientset()
 	fakeIstioClient := istiofake.NewSimpleClientset()
 	var err error
 
@@ -166,7 +166,7 @@ func TestNewIstioGatewaySource(t *testing.T) {
 
 			_, err := NewIstioGatewaySource(
 				context.TODO(),
-				fake.NewSimpleClientset(),
+				fake.NewClientset(),
 				istiofake.NewSimpleClientset(),
 				"",
 				ti.annotationFilter,

source/istio_virtualservice.go

@@ -453,42 +453,16 @@ func (sc *virtualServiceSource) targetsFromIngress(ctx context.Context, ingressS
 	return
 }
 
-func (sc *virtualServiceSource) targetsFromGateway(ctx context.Context, gateway *networkingv1alpha3.Gateway) (targets endpoint.Targets, err error) {
+func (sc *virtualServiceSource) targetsFromGateway(ctx context.Context, gateway *networkingv1alpha3.Gateway) (endpoint.Targets, error) {
-	targets = annotations.TargetsFromTargetAnnotation(gateway.Annotations)
+	targets := annotations.TargetsFromTargetAnnotation(gateway.Annotations)
 	if len(targets) > 0 {
-		return
+		return targets, nil
 	}
 
 	ingressStr, ok := gateway.Annotations[IstioGatewayIngressSource]
 	if ok && ingressStr != "" {
-		targets, err = sc.targetsFromIngress(ctx, ingressStr, gateway)
+		return sc.targetsFromIngress(ctx, ingressStr, gateway)
-		return
 	}
 
-	services, err := sc.serviceInformer.Lister().Services(sc.namespace).List(labels.Everything())
+	return EndpointTargetsFromServices(sc.serviceInformer, sc.namespace, gateway.Spec.Selector)
-	if err != nil {
-		log.Error(err)
-		return
-	}
-
-	for _, service := range services {
-		if !gatewaySelectorMatchesServiceSelector(gateway.Spec.Selector, service.Spec.Selector) {
-			continue
-		}
-
-		if len(service.Spec.ExternalIPs) > 0 {
-			targets = append(targets, service.Spec.ExternalIPs...)
-			continue
-		}
-
-		for _, lb := range service.Status.LoadBalancer.Ingress {
-			if lb.IP != "" {
-				targets = append(targets, lb.IP)
-			} else if lb.Hostname != "" {
-				targets = append(targets, lb.Hostname)
-			}
-		}
-	}
-
-	return
 }

source/istio_virtualservice_test.go

@@ -2035,7 +2035,7 @@ func testGatewaySelectorMatchesService(t *testing.T) {
 		},
 	} {
 		t.Run(ti.title, func(t *testing.T) {
-			require.Equal(t, ti.expected, gatewaySelectorMatchesServiceSelector(ti.gwSelector, ti.lbSelector))
+			require.Equal(t, ti.expected, MatchesServiceSelector(ti.gwSelector, ti.lbSelector))
 		})
 	}
 }