Add e2e test for backend nil service and add nil safeguard (kubernete…

…s#7344)

Co-authored-by: Renato Araujo <renatobritto@protonmail.com>
Co-authored-by: André Goretti <andremotta96@gmail.com>
Co-authored-by: Kalebe Lopes <calbkalebe@gmail.com>

internal/ingress/controller/template/template.go

@@ -1015,6 +1015,10 @@ func getIngressInformation(i, h, p interface{}) *ingressInformation {
 				continue
 			}
 
+			if rPath.Backend.Service == nil {
+				continue
+			}
+
 			if info.Service != "" && rPath.Backend.Service.Name == "" {
 				// empty rule. Only contains a Path and PathType
 				return info

internal/ingress/controller/template/template_test.go

@@ -1140,6 +1140,49 @@ func TestGetIngressInformation(t *testing.T) {
 				ServicePort: "b-svc-80",
 			},
 		},
+		"valid ingress definition with name demo in namespace something and path /ok with a nil backend service": {
+			&ingress.Ingress{
+				Ingress: networking.Ingress{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      "demo",
+						Namespace: "something",
+						Annotations: map[string]string{
+							"ingress.annotation": "ok",
+						},
+					},
+					Spec: networking.IngressSpec{
+						Rules: []networking.IngressRule{
+							{
+								Host: "foo.bar",
+								IngressRuleValue: networking.IngressRuleValue{
+									HTTP: &networking.HTTPIngressRuleValue{
+										Paths: []networking.HTTPIngressPath{
+											{
+												Path:     "/ok",
+												PathType: &pathPrefix,
+												Backend: networking.IngressBackend{
+													Service: nil,
+												},
+											},
+										},
+									},
+								},
+							},
+							{},
+						},
+					},
+				},
+			},
+			"foo.bar",
+			"/ok",
+			&ingressInformation{
+				Namespace: "something",
+				Rule:      "demo",
+				Annotations: map[string]string{
+					"ingress.annotation": "ok",
+				},
+			},
+		},
 	}
 
 	for title, testCase := range testcases {

test/e2e/servicebackend/service_nil_backend.go

@@ -0,0 +1,103 @@
+/*
+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 servicebackend
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/onsi/ginkgo"
+	corev1 "k8s.io/api/core/v1"
+	networking "k8s.io/api/networking/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"k8s.io/ingress-nginx/test/e2e/framework"
+)
+
+var _ = framework.IngressNginxDescribe("[Service] Nil Service Backend", func() {
+	f := framework.NewDefaultFramework("service-nil-backend")
+
+	ginkgo.BeforeEach(func() {
+		f.NewEchoDeployment()
+	})
+
+	ginkgo.It("should return 404 when backend service is nil", func() {
+		ginkgo.By("setting an ingress with a nil backend")
+		validHost := "valid.svc.com"
+		invalidHost := "nilbackend.svc.com"
+
+		ing := framework.NewSingleIngress(validHost, "/", validHost, f.Namespace,
+			framework.EchoService, 80, nil)
+
+		bi := buildIngressWithNonServiceBackend(invalidHost, f.Namespace, "/")
+
+		f.EnsureIngress(bi)
+		f.EnsureIngress(ing)
+
+		f.WaitForNginxConfiguration(func(cfg string) bool {
+			return strings.Contains(cfg, "server_name nilbackend.svc.com") &&
+				strings.Contains(cfg, "server_name valid.svc.com")
+		})
+
+		f.HTTPTestClient().
+			GET("/").
+			WithHeader("Host", validHost).
+			Expect().
+			Status(http.StatusOK)
+
+		f.HTTPTestClient().
+			GET("/").
+			WithHeader("Host", invalidHost).
+			Expect().
+			Status(http.StatusNotFound)
+
+	})
+})
+
+func buildIngressWithNonServiceBackend(host, namespace, path string) *networking.Ingress {
+	apiGroup := "otherobj.testingress.com"
+	obj := corev1.TypedLocalObjectReference{
+		Kind:     "Anything",
+		Name:     "meutest",
+		APIGroup: &apiGroup,
+	}
+
+	return &networking.Ingress{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      host,
+			Namespace: namespace,
+		},
+		Spec: networking.IngressSpec{
+			IngressClassName: framework.GetIngressClassName(namespace),
+			Rules: []networking.IngressRule{
+				{
+					Host: host,
+					IngressRuleValue: networking.IngressRuleValue{
+						HTTP: &networking.HTTPIngressRuleValue{
+							Paths: []networking.HTTPIngressPath{
+								{
+									Path:     path,
+									PathType: &pathtype,
+									Backend: networking.IngressBackend{
+										Resource: &obj,
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+}