Debug problems encountered in #43702

test/e2e/framework/util.go

@@ -346,6 +346,35 @@ func NodeOSDistroIs(supportedNodeOsDistros ...string) bool {
 	return false
 }
 
+func ProxyMode(f *Framework) (string, error) {
+	pod := &v1.Pod{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "kube-proxy-mode-detector",
+			Namespace: f.Namespace.Name,
+		},
+		Spec: v1.PodSpec{
+			HostNetwork: true,
+			Containers: []v1.Container{
+				{
+					Name:    "detector",
+					Image:   "gcr.io/google_containers/e2e-net-amd64:1.0",
+					Command: []string{"/bin/sleep", "3600"},
+				},
+			},
+		},
+	}
+	f.PodClient().CreateSync(pod)
+	defer f.PodClient().DeleteSync(pod.Name, &metav1.DeleteOptions{}, time.Minute)
+
+	cmd := "curl -q -s --connect-timeout 1 http://localhost:10249/proxyMode"
+	stdout, err := RunHostCmd(pod.Namespace, pod.Name, cmd)
+	if err != nil {
+		return "", err
+	}
+	Logf("ProxyMode: %s", stdout)
+	return stdout, nil
+}
+
 func SkipUnlessServerVersionGTE(v *utilversion.Version, c discovery.ServerVersionInterface) {
 	gte, err := ServerVersionGTE(v, c)
 	if err != nil {

test/e2e/service.go

@@ -216,6 +216,16 @@ var _ = framework.KubeDescribe("Services", func() {
 
 	It("should preserve source pod IP for traffic thru service cluster IP", func() {
 
+		// This behavior is not supported if Kube-proxy is in "userspace" mode.
+		// So we check the kube-proxy mode and skip this test if that's the case.
+		if proxyMode, err := framework.ProxyMode(f); err == nil {
+			if proxyMode == "userspace" {
+				framework.Skipf("The test doesn't work with kube-proxy in userspace mode")
+			}
+		} else {
+			framework.Logf("Couldn't detect KubeProxy mode - test failure may be expected: %v", err)
+		}
+
 		serviceName := "sourceip-test"
 		ns := f.Namespace.Name