fix: fix paging in GetAdminAPIsForService

CHANGELOG.md

@@ -67,6 +67,12 @@ Adding a new version? You'll need three changes:
 
 ## Unreleased
 
+### Fixed
+
+- Fix paging in `GetAdminAPIsForService` which might have caused the controller
+  to only return the head of the list of Endpoints for Admin API service.
+  [#3846](https://github.com/Kong/kubernetes-ingress-controller/pull/3846)
+
 ### Deprecated
 
 - Removed support for extensions/v1beta1 Ingress which was removed in kubernetes 1.22.
@@ -88,8 +94,8 @@ Adding a new version? You'll need three changes:
 
 > Release date: 2023-03-29
 
-This release was intended to include a fix for a deadlock in `AdminAPIClientsManager` 
-([#3816](https://github.com/Kong/kubernetes-ingress-controller/pull/3816)), but it wasn't 
+This release was intended to include a fix for a deadlock in `AdminAPIClientsManager`
+([#3816](https://github.com/Kong/kubernetes-ingress-controller/pull/3816)), but it wasn't
 backported properly. It is included in the next patch release.
 
 ## [2.9.0]

internal/adminapi/endpoints.go

@@ -60,6 +60,7 @@ func GetAdminAPIsForService(
 		if endpointsList.Continue == "" {
 			break
 		}
+		continueToken = endpointsList.Continue
 	}
 	return addresses, nil
 }

internal/adminapi/endpoints_envtest_test.go

@@ -0,0 +1,115 @@
+//go:build envtest
+// +build envtest
+
+package adminapi_test
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/samber/lo"
+	"github.com/stretchr/testify/require"
+	corev1 "k8s.io/api/core/v1"
+	discoveryv1 "k8s.io/api/discovery/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/client-go/kubernetes/scheme"
+	ctrlclient "sigs.k8s.io/controller-runtime/pkg/client"
+
+	"github.com/kong/kubernetes-ingress-controller/v2/internal/adminapi"
+	"github.com/kong/kubernetes-ingress-controller/v2/test/envtest"
+)
+
+func TestGetAdminAPIsForServiceReturnsAllAddressesCorrectlyPagingThroughResults(t *testing.T) {
+	t.Parallel()
+
+	var client ctrlclient.Client
+	{
+		cfg := envtest.Setup(t, scheme.Scheme)
+		var err error
+		client, err = ctrlclient.New(cfg, ctrlclient.Options{
+			Scheme: scheme.Scheme,
+		})
+		require.NoError(t, err)
+	}
+
+	// In tests below we use a deferred cancel to stop the manager and not wait
+	// for its timeout.
+
+	testcases := []struct {
+		subnetC int
+		subnetD int
+	}{
+		{subnetC: 1, subnetD: 100},
+		{subnetC: 1, subnetD: 101},
+		{subnetC: 1, subnetD: 250},
+		{subnetC: 2, subnetD: 250},
+		{subnetC: 5, subnetD: 250},
+	}
+
+	for _, tc := range testcases {
+		tc := tc
+		t.Run(fmt.Sprintf("%dx%d", tc.subnetC, tc.subnetD), func(t *testing.T) {
+			t.Parallel()
+
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			var (
+				ns          = envtest.CreateNamespace(ctx, t, client)
+				serviceName = uuid.NewString()
+				service     = types.NamespacedName{
+					Namespace: ns.Name,
+					Name:      serviceName,
+				}
+			)
+
+			for i := 0; i < tc.subnetC; i++ {
+				for j := 0; j < tc.subnetD; j++ {
+					es := discoveryv1.EndpointSlice{
+						ObjectMeta: metav1.ObjectMeta{
+							Name:      uuid.NewString(),
+							Namespace: ns.Name,
+							Labels: map[string]string{
+								"kubernetes.io/service-name": serviceName,
+							},
+						},
+						AddressType: discoveryv1.AddressTypeIPv4,
+						Endpoints: []discoveryv1.Endpoint{
+							{
+								Addresses: []string{fmt.Sprintf("10.0.%d.%d", i, j)},
+								Conditions: discoveryv1.EndpointConditions{
+									Ready:       lo.ToPtr(true),
+									Terminating: lo.ToPtr(false),
+								},
+								TargetRef: testPodReference("pod-1", ns.Name),
+							},
+						},
+						Ports: []discoveryv1.EndpointPort{
+							{
+								Name: lo.ToPtr("admin"),
+								Port: lo.ToPtr(int32(8444)),
+							},
+						},
+					}
+					require.NoError(t, client.Create(ctx, &es))
+				}
+			}
+
+			got, err := adminapi.GetAdminAPIsForService(context.Background(), client, service, sets.New("admin"))
+			require.NoError(t, err)
+			require.Len(t, got, tc.subnetD*tc.subnetC, "GetAdminAPIsForService should return all valid addresses")
+		})
+	}
+}
+
+func testPodReference(name, ns string) *corev1.ObjectReference {
+	return &corev1.ObjectReference{
+		Kind:      "Pod",
+		Namespace: ns,
+		Name:      name,
+	}
+}