[Cherry Pick] - Add configuration to disable external name service feature (#7314) (#7321)

* Add configuration to disable external name service feature (#7314)

Signed-off-by: Ricardo Pchevuzinske Katz <ricardo.katz@gmail.com>

* Fix CI files

test/e2e/settings/disable_service_external_name.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2021 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 settings
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"github.com/gavv/httpexpect/v2"
+	"github.com/onsi/ginkgo"
+	"github.com/stretchr/testify/assert"
+	appsv1 "k8s.io/api/apps/v1"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"k8s.io/ingress-nginx/test/e2e/framework"
+)
+
+var _ = framework.IngressNginxDescribe("[Flag] disable-service-external-name", func() {
+	f := framework.NewDefaultFramework("disabled-service-external-name")
+
+	ginkgo.BeforeEach(func() {
+		f.NewEchoDeploymentWithReplicas(2)
+
+		err := f.UpdateIngressControllerDeployment(func(deployment *appsv1.Deployment) error {
+			args := deployment.Spec.Template.Spec.Containers[0].Args
+			args = append(args, "--disable-svc-external-name=true")
+			deployment.Spec.Template.Spec.Containers[0].Args = args
+			_, err := f.KubeClientSet.AppsV1().Deployments(f.Namespace).Update(context.TODO(), deployment, metav1.UpdateOptions{})
+
+			return err
+		})
+		assert.Nil(ginkgo.GinkgoT(), err, "updating ingress controller deployment flags")
+	})
+
+	ginkgo.It("should ignore services of external-name type", func() {
+
+		nonexternalhost := "echo-svc.com"
+
+		externalhost := "echo-external-svc.com"
+		svcexternal := &corev1.Service{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "external",
+				Namespace: f.Namespace,
+			},
+			Spec: corev1.ServiceSpec{
+				ExternalName: "httpbin.org",
+				Type:         corev1.ServiceTypeExternalName,
+			},
+		}
+		f.EnsureService(svcexternal)
+
+		ingexternal := framework.NewSingleIngress(externalhost, "/", externalhost, f.Namespace, "external", 80, nil)
+		f.EnsureIngress(ingexternal)
+
+		ing := framework.NewSingleIngress(nonexternalhost, "/", nonexternalhost, f.Namespace, framework.EchoService, 80, nil)
+		f.EnsureIngress(ing)
+
+		f.WaitForNginxServer(nonexternalhost, func(cfg string) bool {
+			return strings.Contains(cfg, "server_name echo-svc.com")
+		})
+
+		f.WaitForNginxServer(externalhost, func(cfg string) bool {
+			return strings.Contains(cfg, "server_name echo-external-svc.com")
+		})
+
+		f.HTTPTestClient().
+			GET("/").
+			WithHeader("Host", nonexternalhost).
+			Expect().
+			Status(http.StatusOK)
+
+		f.HTTPTestClient().
+			GET("/").
+			WithHeader("Host", externalhost).
+			Expect().
+			StatusRange(httpexpect.Status5xx)
+
+	})
+})