Add envtest based tests for KongAdminAPIServiceReconciler

[pmalek]

Problem statement

After the introduction of support for Admin API service discovery #702 and hence single controller deployments (partially via KongAdminAPIServiceReconciler) we need to add tests for this functionality.

Some of the related functionality is already being tests with

• UTs e.g. https://github.com/Kong/kubernetes-ingress-controller/blob/93fc98efc6249dfaaa65420b76f22e36ddf602ba/internal/adminapi/endpoints.go
• of E2E tests e.g.

  kubernetes-ingress-controller/test/e2e/all_in_one_test.go

  Lines 318 to 383 in b9b9256

  	func TestDeployAllInOneDBLESSMultiGW(t *testing.T) {
  	t.Parallel()
  	const (
  	manifestFileName = "all-in-one-dbless-multi-gw.yaml"
  	manifestFilePath = "../../deploy/single/" + manifestFileName
  	)
  	t.Logf("configuring %s manifest test", manifestFileName)
  	ctx, env := setupE2ETest(t)
  	t.Log("deploying kong components")
  	f, err := os.Open(manifestFilePath)
  	require.NoError(t, err)
  	defer f.Close()
  	var manifest io.Reader = f
  	manifest, err = patchControllerImageFromEnv(manifest, manifestFilePath)
  	require.NoError(t, err)
  	deployment := deployKong(ctx, t, env, manifest)
  	t.Log("running ingress tests to verify all-in-one deployed ingress controller and proxy are functional")
  	deployIngress(ctx, t, env)
  	verifyIngress(ctx, t, env)
  	gatewayDeployment, err := env.Cluster().Client().AppsV1().Deployments(deployment.Namespace).Get(ctx, "proxy-kong", metav1.GetOptions{})
  	require.NoError(t, err)
  	gatewayDeployment.Spec.Replicas = lo.ToPtr(int32(3))
  	_, err = env.Cluster().Client().AppsV1().Deployments(deployment.Namespace).Update(ctx, gatewayDeployment, metav1.UpdateOptions{})
  	require.NoError(t, err)
  	var podList *corev1.PodList
  	t.Log("waiting all the dataplane instances to be ready")
  	require.Eventually(t, func() bool {
  	forDeployment := metav1.ListOptions{
  	LabelSelector: "app=proxy-kong",
  	}
  	podList, err = env.Cluster().Client().CoreV1().Pods(deployment.Namespace).List(ctx, forDeployment)
  	require.NoError(t, err)
  	return len(podList.Items) == 3
  	}, time.Minute, time.Second)
  	t.Log("confirming that all dataplanes got the config")
  	for _, pod := range podList.Items {
  	client := &http.Client{
  	Timeout: time.Second * 30,
  	Transport: &http.Transport{
  	TLSClientConfig: &tls.Config{
  	InsecureSkipVerify: true, //nolint:gosec
  	},
  	},
  	}
  	forwardCtx, cancel := context.WithCancel(context.Background())
  	defer cancel()
  	localPort := startPortForwarder(forwardCtx, t, env, deployment.Namespace, pod.Name, "8444")
  	address := fmt.Sprintf("https://localhost:%d", localPort)
  	kongClient, err := gokong.NewClient(lo.ToPtr(address), client)
  	require.NoError(t, err)
  	requireIngressConfiguredInAdminAPIEventually(ctx, t, kongClient)
  	t.Logf("proxy pod %s/%s: got the config", pod.Namespace, pod.Name)
  	}
  	}

but ideally we would like like to add some integration tests. This unfortunately is not easy because service discovery is being done via EndpointSlice watch which returns cluster internal addresses.

Proposed solution

Add envtest based tests to test predicates about KongAdminAPIServiceReconciler.