e2e: Autodetect the IP family of the cluster

test/e2e/BUILD

@@ -83,6 +83,7 @@ go_library(
         "//vendor/github.com/onsi/ginkgo/reporters:go_default_library",
         "//vendor/github.com/onsi/gomega:go_default_library",
         "//vendor/k8s.io/klog:go_default_library",
+        "//vendor/k8s.io/utils/net:go_default_library",
     ],
 )
 

test/e2e/e2e.go

@@ -43,6 +43,7 @@ import (
 	e2epod "k8s.io/kubernetes/test/e2e/framework/pod"
 	"k8s.io/kubernetes/test/e2e/manifest"
 	testutils "k8s.io/kubernetes/test/utils"
+	utilnet "k8s.io/utils/net"
 
 	// ensure auth plugins are loaded
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
@@ -143,6 +144,13 @@ var _ = ginkgo.SynchronizedBeforeSuite(func() []byte {
 		e2elog.Logf("kube-apiserver version: %s", serverVersion.GitVersion)
 	}
 
+	// Obtain the (primary if dual stack) ip family of the cluster
+	framework.TestContext.IPFamily = getClusterIPFamily(c)
+	e2elog.Logf("Cluster IP family: %s", framework.TestContext.IPFamily)
+
+	// TODO(dual-stack): dual-stack clusters use two pods addresses (one per family)
+	// the cluster can be ipv4-ipv6 or ipv6-ipv4, order matters
+
 	// Reference common test to make the import valid.
 	commontest.CurrentSuite = commontest.E2E
 
@@ -276,3 +284,18 @@ func runKubernetesServiceTestContainer(c clientset.Interface, ns string) {
 		e2elog.Logf("Output of clusterapi-tester:\n%v", logs)
 	}
 }
+
+// getClusterIPFamily obtains the (primary) ip family of the cluster based
+// on the Cluster IP address of the default kubernetes service
+func getClusterIPFamily(c clientset.Interface) string {
+	// Get the ClusterIP of the kubernetes service created in the default namespace
+	svc, err := c.CoreV1().Services(metav1.NamespaceDefault).Get("kubernetes", metav1.GetOptions{})
+	if err != nil {
+		e2elog.Failf("Failed to get kubernetes endpoints: %v", err)
+	}
+
+	if utilnet.IsIPv6String(svc.Spec.ClusterIP) {
+		return "ipv6"
+	}
+	return "ipv4"
+}

test/e2e/framework/test_context.go

@@ -164,6 +164,9 @@ type TestContextType struct {
 
 	// The configuration of NodeKiller.
 	NodeKiller NodeKillerConfig
+
+	// The IP Family of the cluster
+	IPFamily string
 }
 
 // NodeKillerConfig describes configuration of NodeKiller -- a utility to