add e2e test for Service ExternalIPs

test/e2e/framework/service/jig.go

@@ -829,6 +829,10 @@ func testReachabilityOverClusterIP(clusterIP string, sp v1.ServicePort, execPod
 	return nil
 }
 
+func testReachabilityOverExternalIP(externalIP string, sp v1.ServicePort, execPod *v1.Pod) error {
+	return testEndpointReachability(externalIP, sp.Port, sp.Protocol, execPod)
+}
+
 func testReachabilityOverNodePorts(nodes *v1.NodeList, sp v1.ServicePort, pod *v1.Pod, clusterIP string) error {
 	internalAddrs := e2enode.CollectAddresses(nodes, v1.NodeInternalIP)
 	externalAddrs := e2enode.CollectAddresses(nodes, v1.NodeExternalIP)
@@ -911,6 +915,7 @@ func testEndpointReachability(endpoint string, port int32, protocol v1.Protocol,
 func (j *TestJig) checkClusterIPServiceReachability(svc *v1.Service, pod *v1.Pod) error {
 	clusterIP := svc.Spec.ClusterIP
 	servicePorts := svc.Spec.Ports
+	externalIPs := svc.Spec.ExternalIPs
 
 	err := j.waitForAvailableEndpoint(ServiceEndpointsTimeout)
 	if err != nil {
@@ -926,6 +931,14 @@ func (j *TestJig) checkClusterIPServiceReachability(svc *v1.Service, pod *v1.Pod
 		if err != nil {
 			return err
 		}
+		if len(externalIPs) > 0 {
+			for _, externalIP := range externalIPs {
+				err = testReachabilityOverExternalIP(externalIP, servicePort, pod)
+				if err != nil {
+					return err
+				}
+			}
+		}
 	}
 	return nil
 }

test/e2e/network/service.go

@@ -1217,6 +1217,37 @@ var _ = SIGDescribe("Services", func() {
 		framework.ExpectNoError(err)
 	})
 
+	/*
+		Create a ClusterIP service with an External IP that is not assigned to an interface.
+		The IP ranges here are reserved for documentation according to
+		[RFC 5737](https://tools.ietf.org/html/rfc5737) Section 3 and should not be used by any host.
+	*/
+	ginkgo.It("should be possible to connect to a service via ExternalIP when the external IP is not assigned to a node", func() {
+		serviceName := "externalip-test"
+		ns := f.Namespace.Name
+		externalIP := "203.0.113.250"
+		if framework.TestContext.ClusterIsIPv6() {
+			externalIP = "2001:DB8::cb00:71fa"
+		}
+
+		jig := e2eservice.NewTestJig(cs, ns, serviceName)
+
+		ginkgo.By("creating service " + serviceName + " with type=clusterIP in namespace " + ns)
+		clusterIPService, err := jig.CreateTCPService(func(svc *v1.Service) {
+			svc.Spec.Type = v1.ServiceTypeClusterIP
+			svc.Spec.ExternalIPs = []string{externalIP}
+			svc.Spec.Ports = []v1.ServicePort{
+				{Port: 80, Name: "http", Protocol: v1.ProtocolTCP, TargetPort: intstr.FromInt(9376)},
+			}
+		})
+		framework.ExpectNoError(err)
+		err = jig.CreateServicePods(2)
+		framework.ExpectNoError(err)
+		execPod := e2epod.CreateExecPodOrFail(cs, ns, "execpod", nil)
+		err = jig.CheckServiceReachability(clusterIPService, execPod)
+		framework.ExpectNoError(err)
+	})
+
 	// TODO: Get rid of [DisabledForLargeClusters] tag when issue #56138 is fixed.
 	ginkgo.It("should be able to change the type and ports of a service [Slow] [DisabledForLargeClusters]", func() {
 		// requires cloud load-balancer support