Make TestContext.IPFamily global for parallel testing

it turns out that the framework.TestContext.IPFamily variable is
not available for the DNS tests if they don't run in the initial
Ginkgo node when running in parallel.

We add a function to the framework to allow us to run command
only once per each Ginkgo node parallel execution.

It also adds a method to detect if the cluster is IPv6.

The use of the framework.TestContext.IPFamily variable guarantees
consistency all over the testing because this variable is only
assigned at the beginning of the testing.

Author: aojea

test/e2e/e2e.go

@@ -53,6 +53,7 @@ var _ = ginkgo.SynchronizedBeforeSuite(func() []byte {
 	return nil
 }, func(data []byte) {
 	// Run on all Ginkgo nodes
+	framework.SetupSuitePerGinkgoNode()
 })
 
 var _ = ginkgo.SynchronizedAfterSuite(func() {

test/e2e/framework/log/logger_test.go

@@ -84,7 +84,7 @@ func TestFailureOutput(t *testing.T) {
 			output:  "INFO: before\nFAIL: hard-coded error\nUnexpected error:\n    <*errors.errorString>: {\n        s: \"an error with a long, useless description\",\n    }\n    an error with a long, useless description\noccurred\nINFO: after\nFAIL: true is never false either\nExpected\n    <bool>: true\nto equal\n    <bool>: false\n",
 			failure: "hard-coded error\nUnexpected error:\n    <*errors.errorString>: {\n        s: \"an error with a long, useless description\",\n    }\n    an error with a long, useless description\noccurred",
 			// TODO: should start with k8s.io/kubernetes/test/e2e/framework/log_test.glob..func1.4()
-			stack: "\tutil.go:1362\nk8s.io/kubernetes/test/e2e/framework.ExpectNoError()\n\tutil.go:1356\nk8s.io/kubernetes/test/e2e/framework/log_test.glob..func1.4()\n\tlogger_test.go:49\nk8s.io/kubernetes/vendor/github.com/onsi/ginkgo/internal/leafnodes.(*runner).runSync()\n\tlogger_test.go:65\n",
+			stack: "\tutil.go:1369\nk8s.io/kubernetes/test/e2e/framework.ExpectNoError()\n\tutil.go:1363\nk8s.io/kubernetes/test/e2e/framework/log_test.glob..func1.4()\n\tlogger_test.go:49\nk8s.io/kubernetes/vendor/github.com/onsi/ginkgo/internal/leafnodes.(*runner).runSync()\n\tlogger_test.go:65\n",
 		},
 		testResult{
 			name:    "[Top Level] log fails",

test/e2e/framework/suites.go

@@ -116,21 +116,30 @@ func SetupSuite() {
 		e2elog.Logf("kube-apiserver version: %s", serverVersion.GitVersion)
 	}
 
+	if TestContext.NodeKiller.Enabled {
+		nodeKiller := NewNodeKiller(TestContext.NodeKiller, c, TestContext.Provider)
+		go nodeKiller.Run(TestContext.NodeKiller.NodeKillerStopCh)
+	}
+}
+
+// SetupSuitePerGinkgoNode is the boilerplate that can be used to setup ginkgo test suites, on the SynchronizedBeforeSuite step.
+// There are certain operations we only want to run once per overall test invocation on each Ginkgo node
+// such as making some global variables accessible to all parallel executions
+// Because of the way Ginkgo runs tests in parallel, we must use SynchronizedBeforeSuite
+// Ref: https://onsi.github.io/ginkgo/#parallel-specs
+func SetupSuitePerGinkgoNode() {
 	// Obtain the default IP family of the cluster
 	// Some e2e test are designed to work on IPv4 only, this global variable
 	// allows to adapt those tests to work on both IPv4 and IPv6
-	// TODO(dual-stack): dual stack clusters should pass full e2e testing at least with the primary IP family
+	// TODO: dual-stack
 	// the dual stack clusters can be ipv4-ipv6 or ipv6-ipv4, order matters,
 	// and services use the primary IP family by default
-	// If we´ll need to provide additional context for dual-stack, we can detect it
-	// because pods have two addresses (one per family)
+	c, err := LoadClientset()
+	if err != nil {
+		klog.Fatal("Error loading client: ", err)
+	}
 	TestContext.IPFamily = getDefaultClusterIPFamily(c)
 	e2elog.Logf("Cluster IP family: %s", TestContext.IPFamily)
-
-	if TestContext.NodeKiller.Enabled {
-		nodeKiller := NewNodeKiller(TestContext.NodeKiller, c, TestContext.Provider)
-		go nodeKiller.Run(TestContext.NodeKiller.NodeKillerStopCh)
-	}
 }
 
 // CleanupSuite is the boilerplate that can be used after tests on ginkgo were run, on the SynchronizedAfterSuite step.

test/e2e/framework/util.go

@@ -415,6 +415,8 @@ func runKubernetesServiceTestContainer(c clientset.Interface, ns string) {
 // getDefaultClusterIPFamily obtains the default IP family of the cluster
 // using the Cluster IP address of the kubernetes service created in the default namespace
 // This unequivocally identifies the default IP family because services are single family
+// TODO: dual-stack may support multiple families per service
+// but we can detect if a cluster is dual stack because pods have two addresses (one per family)
 func getDefaultClusterIPFamily(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{})
@@ -428,6 +430,11 @@ func getDefaultClusterIPFamily(c clientset.Interface) string {
 	return "ipv4"
 }
 
+// ClusterIsIPv6 returns true if the cluster is IPv6
+func ClusterIsIPv6() bool {
+	return TestContext.IPFamily == "ipv6"
+}
+
 // ProviderIs returns true if the provider is included is the providers. Otherwise false.
 func ProviderIs(providers ...string) bool {
 	for _, provider := range providers {