Fix service type external name using the name

internal/ingress/controller/controller.go

@@ -835,9 +835,9 @@ func (n *NGINXController) getServiceClusterEndpoint(svcKey string, backend *netw
 
 // serviceEndpoints returns the upstream servers (Endpoints) associated with a Service.
 func (n *NGINXController) serviceEndpoints(svcKey, backendPort string) ([]ingress.Endpoint, error) {
-	svc, err := n.store.GetService(svcKey)
-
 	var upstreams []ingress.Endpoint
+
+	svc, err := n.store.GetService(svcKey)
 	if err != nil {
 		return upstreams, err
 	}
@@ -848,14 +848,26 @@ func (n *NGINXController) serviceEndpoints(svcKey, backendPort string) ([]ingres
 	if svc.Spec.Type == apiv1.ServiceTypeExternalName {
 		externalPort, err := strconv.Atoi(backendPort)
 		if err != nil {
-			klog.Warningf("Only numeric ports are allowed in ExternalName Services: %q is not a valid port number.", backendPort)
+			// check if the service ports have one with backendPort as name
+			found := false
+			for _, port := range svc.Spec.Ports {
+				if port.Name == backendPort {
+					externalPort = int(port.Port)
+					found = true
+					break
+				}
+			}
+
+			if !found {
+				klog.Errorf("service %v/%v does not have a port with name %v", svc.Namespace, svc.Namespace, backendPort)
 				return upstreams, nil
 			}
+		}
 
 		servicePort := apiv1.ServicePort{
 			Protocol:   "TCP",
 			Port:       int32(externalPort),
-			TargetPort: intstr.FromString(backendPort),
+			TargetPort: intstr.FromInt(externalPort),
 		}
 		endps := getEndpoints(svc, &servicePort, apiv1.ProtocolTCP, n.store.GetServiceEndpoints)
 		if len(endps) == 0 {

test/e2e/servicebackend/service_externalname.go

@@ -177,4 +177,45 @@ var _ = framework.IngressNginxDescribe("Service Type ExternalName", func() {
 		Expect(errs).Should(BeEmpty())
 		Expect(resp.StatusCode).Should(Equal(503))
 	})
+
+	It("should return 200 for service type=ExternalName using a port name", func() {
+		host := "echo"
+
+		svc := &core.Service{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      "httpbin",
+				Namespace: f.Namespace,
+			},
+			Spec: corev1.ServiceSpec{
+				ExternalName: "httpbin.org",
+				Type:         corev1.ServiceTypeExternalName,
+				Ports: []corev1.ServicePort{
+					{
+						Name:       host,
+						Port:       80,
+						TargetPort: intstr.FromInt(80),
+						Protocol:   "TCP",
+					},
+				},
+			},
+		}
+		f.EnsureService(svc)
+
+		ing := framework.NewSingleIngress(host, "/", host, f.Namespace, "httpbin", 80, nil)
+		ing.Spec.Rules[0].HTTP.Paths[0].Backend.ServicePort = intstr.FromString(host)
+		f.EnsureIngress(ing)
+
+		f.WaitForNginxServer(host,
+			func(server string) bool {
+				return strings.Contains(server, "proxy_pass http://upstream_balancer;")
+			})
+
+		resp, _, errs := gorequest.New().
+			Get(f.GetURL(framework.HTTP)+"/get").
+			Set("Host", host).
+			End()
+		Expect(errs).Should(BeEmpty())
+		Expect(resp.StatusCode).Should(Equal(200))
+	})
+
 })