Add IPv6 support to the Container Lifecycle tests

Current e2e tests for the Container Lifecycle Hooks weren't
using brackets for the IPv6 URL addresses per RFC2732, thus those
tests were failing.

This patches add brackets to the target URL if it's an IPv6 address.

Reference: https://github.com/kubernetes/kubernetes/issues/70248

test/e2e/common/lifecycle_hook.go

@@ -17,6 +17,8 @@ limitations under the License.
 package common
 
 import (
+	"fmt"
+	"strings"
 	"time"
 
 	"k8s.io/api/core/v1"
@@ -38,7 +40,7 @@ var _ = framework.KubeDescribe("Container Lifecycle Hook", func() {
 		preStopWaitTimeout   = 30 * time.Second
 	)
 	Context("when create a pod with lifecycle hook", func() {
-		var targetIP string
+		var targetIP, targetURL string
 		podHandleHookRequest := &v1.Pod{
 			ObjectMeta: metav1.ObjectMeta{
 				Name: "pod-handle-http-request",
@@ -63,6 +65,10 @@ var _ = framework.KubeDescribe("Container Lifecycle Hook", func() {
 			By("create the container to handle the HTTPGet hook request.")
 			newPod := podClient.CreateSync(podHandleHookRequest)
 			targetIP = newPod.Status.PodIP
+			targetURL = targetIP
+			if strings.Contains(targetIP, ":") {
+				targetURL = fmt.Sprintf("[%s]", targetIP)
+			}
 		})
 		testPodWithHook := func(podWithHook *v1.Pod) {
 			By("create the pod with lifecycle hook")
@@ -93,7 +99,7 @@ var _ = framework.KubeDescribe("Container Lifecycle Hook", func() {
 			lifecycle := &v1.Lifecycle{
 				PostStart: &v1.Handler{
 					Exec: &v1.ExecAction{
-						Command: []string{"sh", "-c", "curl http://" + targetIP + ":8080/echo?msg=poststart"},
+						Command: []string{"sh", "-c", "curl http://" + targetURL + ":8080/echo?msg=poststart"},
 					},
 				},
 			}
@@ -109,7 +115,7 @@ var _ = framework.KubeDescribe("Container Lifecycle Hook", func() {
 			lifecycle := &v1.Lifecycle{
 				PreStop: &v1.Handler{
 					Exec: &v1.ExecAction{
-						Command: []string{"sh", "-c", "curl http://" + targetIP + ":8080/echo?msg=prestop"},
+						Command: []string{"sh", "-c", "curl http://" + targetURL + ":8080/echo?msg=prestop"},
 					},
 				},
 			}