Add e2e test for forwarding PTR records to upstream nameserver.

createDNSServerWithPtrRecord in dns_common.go is added to generate dns
server pod with PTR record.

test/e2e/network/dns.go

@@ -318,4 +318,5 @@ var _ = SIGDescribe("DNS", func() {
 
 		// TODO: Add more test cases for other DNSPolicies.
 	})
+
 })

test/e2e/network/dns_common.go

@@ -110,6 +110,9 @@ func (t *dnsTestCommon) runDig(dnsName, target string) []string {
 	default:
 		panic(fmt.Errorf("invalid target: " + target))
 	}
+	if strings.HasSuffix(dnsName, "in-addr.arpa") || strings.HasSuffix(dnsName, "in-addr.arpa.") {
+		cmd = append(cmd, []string{"-t", "ptr"}...)
+	}
 	cmd = append(cmd, dnsName)
 
 	stdout, stderr, err := t.f.ExecWithOptions(framework.ExecOptions{
@@ -266,8 +269,8 @@ func generateDNSServerPod(aRecords map[string]string) *v1.Pod {
 	return pod
 }
 
-func (t *dnsTestCommon) createDNSServer(aRecords map[string]string) {
+func (t *dnsTestCommon) createDNSPodFromObj(pod *v1.Pod) {
-	t.dnsServerPod = generateDNSServerPod(aRecords)
+	t.dnsServerPod = pod
 
 	var err error
 	t.dnsServerPod, err = t.c.CoreV1().Pods(t.f.Namespace.Name).Create(t.dnsServerPod)
@@ -280,6 +283,40 @@ func (t *dnsTestCommon) createDNSServer(aRecords map[string]string) {
 	Expect(err).NotTo(HaveOccurred())
 }
 
+func (t *dnsTestCommon) createDNSServer(aRecords map[string]string) {
+	t.createDNSPodFromObj(generateDNSServerPod(aRecords))
+}
+
+func (t *dnsTestCommon) createDNSServerWithPtrRecord() {
+	pod := &v1.Pod{
+		TypeMeta: metav1.TypeMeta{
+			Kind: "Pod",
+		},
+		ObjectMeta: metav1.ObjectMeta{
+			GenerateName: "e2e-dns-configmap-dns-server-",
+		},
+		Spec: v1.PodSpec{
+			Containers: []v1.Container{
+				{
+					Name:  "dns",
+					Image: imageutils.GetE2EImage(imageutils.DNSMasq),
+					Command: []string{
+						"/usr/sbin/dnsmasq",
+						"-u", "root",
+						"-k",
+						"--log-facility", "-",
+						"--host-record=my.test,192.0.2.123",
+						"-q",
+					},
+				},
+			},
+			DNSPolicy: "Default",
+		},
+	}
+
+	t.createDNSPodFromObj(pod)
+}
+
 func (t *dnsTestCommon) deleteDNSServerPod() {
 	podClient := t.c.CoreV1().Pods(t.f.Namespace.Name)
 	if err := podClient.Delete(t.dnsServerPod.Name, metav1.NewDeleteOptions(0)); err != nil {

test/e2e/network/dns_configmap.go

@@ -34,10 +34,10 @@ type dnsFederationsConfigMapTest struct {
 }
 
 var _ = SIGDescribe("DNS configMap federations", func() {
-	t := &dnsNameserverTest{dnsTestCommon: newDnsTestCommon()}
-	BeforeEach(func() { t.c = t.f.ClientSet })
 
 	It("should be able to change federation configuration [Slow][Serial]", func() {
+		t := &dnsNameserverTest{dnsTestCommon: newDnsTestCommon()}
+		t.c = t.f.ClientSet
 		t.run()
 	})
 })
@@ -185,11 +185,50 @@ func (t *dnsNameserverTest) run() {
 		moreForeverTestTimeout)
 }
 
+type dnsPtrFwdTest struct {
+	dnsTestCommon
+}
+
+func (t *dnsPtrFwdTest) run() {
+	t.init()
+
+	t.createUtilPod()
+	defer t.deleteUtilPod()
+
+	t.createDNSServerWithPtrRecord()
+	defer t.deleteDNSServerPod()
+
+	t.setConfigMap(&v1.ConfigMap{Data: map[string]string{
+		"upstreamNameservers": fmt.Sprintf(`["%v"]`, t.dnsServerPod.Status.PodIP),
+	}})
+
+	moreForeverTestTimeout := 2 * 60 * time.Second
+
+	t.checkDNSRecordFrom(
+		"123.2.0.192.in-addr.arpa",
+		func(actual []string) bool { return len(actual) == 1 && actual[0] == "my.test." },
+		"dnsmasq",
+		moreForeverTestTimeout)
+
+	t.c.CoreV1().ConfigMaps(t.ns).Delete(t.name, nil)
+	t.checkDNSRecordFrom(
+		"123.2.0.192.in-addr.arpa",
+		func(actual []string) bool { return len(actual) == 0 },
+		"dnsmasq",
+		moreForeverTestTimeout)
+}
+
 var _ = SIGDescribe("DNS configMap nameserver", func() {
-	t := &dnsNameserverTest{dnsTestCommon: newDnsTestCommon()}
-	BeforeEach(func() { t.c = t.f.ClientSet })
 
 	It("should be able to change stubDomain configuration [Slow][Serial]", func() {
-		t.run()
+		nsTest := &dnsNameserverTest{dnsTestCommon: newDnsTestCommon()}
+		nsTest.c = nsTest.f.ClientSet
+		nsTest.run()
+	})
+
+	It("should forward PTR records lookup to upstream nameserver [Slow][Serial]", func() {
+		fwdTest := &dnsPtrFwdTest{dnsTestCommon: newDnsTestCommon()}
+		fwdTest.c = fwdTest.f.ClientSet
+		fwdTest.run()
 	})
 })