Merge pull request #11790 from smarterclayton/support_external_name_dns

Merged by openshift-bot

Author: OpenShift Bot

pkg/dns/serviceresolver.go

@@ -128,7 +128,7 @@ func (b *ServiceResolver) Records(dnsName string, exact bool) ([]msg.Service, er
 		}
 
 		// no clusterIP and not headless, no DNS
-		if len(svc.Spec.ClusterIP) == 0 {
+		if len(svc.Spec.ClusterIP) == 0 && svc.Spec.Type != kapi.ServiceTypeExternalName {
 			return nil, errNoSuchName
 		}
 
@@ -140,8 +140,13 @@ func (b *ServiceResolver) Records(dnsName string, exact bool) ([]msg.Service, er
 
 		// if has a portal IP and looking at svc
 		if svc.Spec.ClusterIP != kapi.ClusterIPNone && !retrieveEndpoints {
+			hostValue := svc.Spec.ClusterIP
+			if svc.Spec.Type == kapi.ServiceTypeExternalName {
+				hostValue = svc.Spec.ExternalName
+			}
+
 			defaultService := msg.Service{
-				Host: svc.Spec.ClusterIP,
+				Host: hostValue,
 				Port: 0,
 
 				Priority: 10,
@@ -153,6 +158,7 @@ func (b *ServiceResolver) Records(dnsName string, exact bool) ([]msg.Service, er
 			defaultService.Key = msg.Path(defaultName)
 
 			if len(svc.Spec.Ports) == 0 || !includePorts {
+				glog.V(4).Infof("Answered %s:%t with %#v", dnsName, exact, defaultService)
 				return []msg.Service{defaultService}, nil
 			}
 
@@ -175,7 +181,7 @@ func (b *ServiceResolver) Records(dnsName string, exact bool) ([]msg.Service, er
 				keyName := buildDNSName(defaultName, protocolSegment, portSegment)
 				services = append(services,
 					msg.Service{
-						Host: svc.Spec.ClusterIP,
+						Host: hostValue,
 						Port: int(port),
 
 						Priority: 10,

test/extended/dns/dns.go

@@ -64,6 +64,23 @@ func digForNames(namesToResolve []string, expect sets.String) string {
 	return probeCmd
 }
 
+func digForCNAMEs(namesToResolve []string, expect sets.String) string {
+	fileNamePrefix := "test"
+	var probeCmd string
+	for _, name := range namesToResolve {
+		// Resolve by TCP and UDP DNS.  Use $$(...) because $(...) is
+		// expanded by kubernetes (though this won't expand so should
+		// remain a literal, safe > sorry).
+		lookup := "CNAME"
+		fileName := fmt.Sprintf("%s_udp@%s", fileNamePrefix, name)
+		expect.Insert(fileName)
+		probeCmd += fmt.Sprintf(`test -n "$$(dig +notcp +noall +answer +search %s %s)" && echo %q;`, name, lookup, fileName)
+		fileName = fmt.Sprintf("%s_tcp@%s", fileNamePrefix, name)
+		expect.Insert(fileName)
+		probeCmd += fmt.Sprintf(`test -n "$$(dig +tcp +noall +answer +search %s %s)" && echo %q;`, name, lookup, fileName)
+	}
+	return probeCmd
+}
 func digForARecords(records map[string][]string, expect sets.String) string {
 	var probeCmd string
 	fileNamePrefix := "test"
@@ -178,8 +195,8 @@ func validateDNSResults(f *e2e.Framework, pod *api.Pod, fileNames sets.String, e
 	e2e.Logf("DNS probes using %s succeeded\n", pod.Name)
 }
 
-func createServiceSpec(serviceName string, isHeadless bool, selector map[string]string) *api.Service {
-	headlessService := &api.Service{
+func createServiceSpec(serviceName string, isHeadless bool, externalName string, selector map[string]string) *api.Service {
+	s := &api.Service{
 		ObjectMeta: api.ObjectMeta{
 			Name: serviceName,
 		},
@@ -191,9 +208,14 @@ func createServiceSpec(serviceName string, isHeadless bool, selector map[string]
 		},
 	}
 	if isHeadless {
-		headlessService.Spec.ClusterIP = "None"
+		s.Spec.ClusterIP = "None"
 	}
-	return headlessService
+	if len(externalName) > 0 {
+		s.Spec.Type = api.ServiceTypeExternalName
+		s.Spec.ExternalName = externalName
+		s.Spec.ClusterIP = ""
+	}
+	return s
 }
 
 func createEndpointSpec(name string) *api.Endpoints {
@@ -233,18 +255,21 @@ var _ = Describe("DNS", func() {
 	f := e2e.NewDefaultFramework("dns")
 
 	It("should answer endpoint and wildcard queries for the cluster [Conformance]", func() {
-		if _, err := f.Client.Services(f.Namespace.Name).Create(createServiceSpec("headless", true, nil)); err != nil {
+		if _, err := f.Client.Services(f.Namespace.Name).Create(createServiceSpec("headless", true, "", nil)); err != nil {
 			e2e.Failf("unable to create headless service: %v", err)
 		}
 		if _, err := f.Client.Endpoints(f.Namespace.Name).Create(createEndpointSpec("headless")); err != nil {
 			e2e.Failf("unable to create clusterip endpoints: %v", err)
 		}
-		if _, err := f.Client.Services(f.Namespace.Name).Create(createServiceSpec("clusterip", false, nil)); err != nil {
+		if _, err := f.Client.Services(f.Namespace.Name).Create(createServiceSpec("clusterip", false, "", nil)); err != nil {
 			e2e.Failf("unable to create clusterip service: %v", err)
 		}
 		if _, err := f.Client.Endpoints(f.Namespace.Name).Create(createEndpointSpec("clusterip")); err != nil {
 			e2e.Failf("unable to create clusterip endpoints: %v", err)
 		}
+		if _, err := f.Client.Services(f.Namespace.Name).Create(createServiceSpec("externalname", true, "www.google.com", nil)); err != nil {
+			e2e.Failf("unable to create externalName service: %v", err)
+		}
 
 		ep, err := f.Client.Endpoints("default").Get("kubernetes")
 		if err != nil {
@@ -270,6 +295,11 @@ var _ = Describe("DNS", func() {
 				fmt.Sprintf("prefix.clusterip.%s", f.Namespace.Name),
 			}, expect),
 
+			// the DNS pod should be able to get a CNAME for this service
+			digForCNAMEs([]string{
+				fmt.Sprintf("externalname.%s.svc", f.Namespace.Name),
+			}, expect),
+
 			// the DNS pod should be able to look up endpoints for names and wildcards
 			digForARecords(map[string][]string{
 				"kubernetes.default.endpoints": kubeEndpoints,

test/extended/setup.sh

@@ -291,6 +291,8 @@ readonly CONFORMANCE_TESTS=(
 	"Ensure supplemental groups propagate to docker"
 	"EmptyDir"
 	"PetSet"
+	"DNS for ExternalName services"
+	"DNS for pods for Hostname and Subdomain annotation"
 	"PrivilegedPod should test privileged pod"
 	"Pods should support remote command execution"
 	"Pods should support retrieving logs from the container"