Add test cases for Service with restartable init containers

* Add a test case to verify that specifying a port number
  as the target port for restartable init containers in Service
* Add a failing test case to verify that specifying a named port
  as the target port for restartable init containers in Service

test/e2e/network/service.go

@@ -4076,6 +4076,78 @@ var _ = common.SIGDescribe("Services", func() {
 		checkOneNodePort(hostExecPodNodeIP, true, v1.ServiceExternalTrafficPolicyLocal, deadline)
 		checkOneNodePort(thirdNodeIP, false, v1.ServiceExternalTrafficPolicyLocal, deadline)
 	})
+
+	ginkgo.It("should connect to the ports exposed by restartable init containers", func(ctx context.Context) {
+		serviceName := "sidecar-with-port"
+		ns := f.Namespace.Name
+
+		t := NewServerTest(cs, ns, serviceName)
+		defer func() {
+			defer ginkgo.GinkgoRecover()
+			errs := t.Cleanup()
+			if len(errs) != 0 {
+				framework.Failf("errors in cleanup: %v", errs)
+			}
+		}()
+
+		name := "sidecar-port"
+		port := int32(8080)
+		namedPort := "http-sidecar"
+
+		service := t.BuildServiceSpec()
+		service.Spec.Ports = []v1.ServicePort{
+			{
+				Name:       namedPort,
+				Port:       port,
+				TargetPort: intstr.FromInt(int(port)),
+			},
+		}
+		ports := []v1.ContainerPort{{Name: namedPort, ContainerPort: port, Protocol: v1.ProtocolTCP}}
+		args := []string{"netexec", fmt.Sprintf("--http-port=%d", port)}
+		createPodWithRestartableInitContainerOrFail(ctx, f, ns, name, t.Labels, ports, args...)
+
+		ginkgo.By(fmt.Sprintf("creating Service %v with selectors %v", service.Name, service.Spec.Selector))
+		service, err := t.CreateService(service)
+		framework.ExpectNoError(err)
+
+		checkServiceReachabilityFromExecPod(ctx, f.ClientSet, ns, service.Name, service.Spec.ClusterIP, port)
+	})
+
+	ginkgo.It("should connect to the named ports exposed by restartable init containers", func(ctx context.Context) {
+		serviceName := "sidecar-with-named-port"
+		ns := f.Namespace.Name
+
+		t := NewServerTest(cs, ns, serviceName)
+		defer func() {
+			defer ginkgo.GinkgoRecover()
+			errs := t.Cleanup()
+			if len(errs) != 0 {
+				framework.Failf("errors in cleanup: %v", errs)
+			}
+		}()
+
+		name := "sidecar-port"
+		port := int32(8080)
+		namedPort := "http-sidecar"
+
+		service := t.BuildServiceSpec()
+		service.Spec.Ports = []v1.ServicePort{
+			{
+				Name:       namedPort,
+				Port:       port,
+				TargetPort: intstr.FromString(namedPort),
+			},
+		}
+		ports := []v1.ContainerPort{{Name: namedPort, ContainerPort: port, Protocol: v1.ProtocolTCP}}
+		args := []string{"netexec", fmt.Sprintf("--http-port=%d", port)}
+		createPodWithRestartableInitContainerOrFail(ctx, f, ns, name, t.Labels, ports, args...)
+
+		ginkgo.By(fmt.Sprintf("creating Service %v with selectors %v", service.Name, service.Spec.Selector))
+		service, err := t.CreateService(service)
+		framework.ExpectNoError(err)
+
+		checkServiceReachabilityFromExecPod(ctx, f.ClientSet, ns, service.Name, service.Spec.ClusterIP, port)
+	})
 })
 
 // execAffinityTestForSessionAffinityTimeout is a helper function that wrap the logic of
@@ -4325,6 +4397,18 @@ func createPodOrFail(ctx context.Context, f *framework.Framework, ns, name strin
 	e2epod.NewPodClient(f).CreateSync(ctx, pod)
 }
 
+// createPodWithRestartableInitContainerOrFail creates a pod with restartable init containers using the specified containerPorts.
+func createPodWithRestartableInitContainerOrFail(ctx context.Context, f *framework.Framework, ns, name string, labels map[string]string, containerPorts []v1.ContainerPort, args ...string) {
+	ginkgo.By(fmt.Sprintf("Creating pod %s with restartable init containers in namespace %s", name, ns))
+	pod := e2epod.NewAgnhostPod(ns, name, nil, nil, nil, "pause")
+	pod.ObjectMeta.Labels = labels
+	restartPolicyAlways := v1.ContainerRestartPolicyAlways
+	init := e2epod.NewAgnhostContainer(name, nil, containerPorts, args...)
+	init.RestartPolicy = &restartPolicyAlways
+	pod.Spec.InitContainers = []v1.Container{init}
+	e2epod.NewPodClient(f).CreateSync(ctx, pod)
+}
+
 // launchHostExecPod launches a hostexec pod in the given namespace and waits
 // until it's Running. If avoidNode is non-nil, it will ensure that the pod doesn't
 // land on that node.
@@ -4375,6 +4459,30 @@ func checkReachabilityFromPod(ctx context.Context, expectToBeReachable bool, tim
 	framework.ExpectNoError(err)
 }
 
+// checkServiceReachabilityFromExecPod creates a dedicated client pod, executes into it,
+// and checks reachability to the specified target host and port.
+func checkServiceReachabilityFromExecPod(ctx context.Context, client clientset.Interface, namespace, name, clusterIP string, port int32) {
+	// We avoid relying on DNS lookup with the service name here because
+	// we only want to test whether the named port is accessible from the service.
+	serverHost := net.JoinHostPort(clusterIP, strconv.Itoa(int(port)))
+	ginkgo.By("creating a dedicated client to send request to the http server " + serverHost)
+	execPod := e2epod.CreateExecPodOrFail(ctx, client, namespace, "execpod-", nil)
+	execPodName := execPod.Name
+	cmd := fmt.Sprintf("curl -q -s --connect-timeout 2 http://%s/", serverHost)
+	var stdout string
+	if pollErr := wait.PollUntilContextTimeout(ctx, framework.Poll, e2eservice.KubeProxyLagTimeout, true, func(ctx context.Context) (bool, error) {
+		var err error
+		stdout, err = e2eoutput.RunHostCmd(namespace, execPodName, cmd)
+		if err != nil {
+			framework.Logf("error trying to connect to service %s: %v, ... retrying", name, err)
+			return false, nil
+		}
+		return true, nil
+	}); pollErr != nil {
+		framework.Failf("connection to the Service %v within %v should be succeeded, stdout: %v", name, e2eservice.KubeProxyLagTimeout, stdout)
+	}
+}
+
 func validatePorts(ep, expectedEndpoints portsByPodUID) error {
 	if len(ep) != len(expectedEndpoints) {
 		// should not happen because we check this condition before