plugin/kubernetes: Add support for dual stack ClusterIP Services (#4339)

* support dual stack clusterIPs
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* stickler
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

* fix ClusterIPs make
Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

plugin/k8s_external/external_test.go

@@ -190,7 +190,7 @@ var svcIndexExternal = map[string][]*object.Service{
 			Name:        "svc1",
 			Namespace:   "testns",
 			Type:        api.ServiceTypeClusterIP,
-			ClusterIP:   "10.0.0.1",
+			ClusterIPs:  []string{"10.0.0.1"},
 			ExternalIPs: []string{"1.2.3.4"},
 			Ports:       []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},
@@ -200,7 +200,7 @@ var svcIndexExternal = map[string][]*object.Service{
 			Name:        "svc6",
 			Namespace:   "testns",
 			Type:        api.ServiceTypeClusterIP,
-			ClusterIP:   "10.0.0.3",
+			ClusterIPs:  []string{"10.0.0.3"},
 			ExternalIPs: []string{"1:2::5"},
 			Ports:       []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},

plugin/kubernetes/controller.go

@@ -200,11 +200,13 @@ func svcIPIndexFunc(obj interface{}) ([]string, error) {
 	if !ok {
 		return nil, errObj
 	}
+	idx := make([]string, len(svc.ClusterIPs)+len(svc.ExternalIPs))
+	copy(idx, svc.ClusterIPs)
 	if len(svc.ExternalIPs) == 0 {
-		return []string{svc.ClusterIP}, nil
+		return idx, nil
 	}
-
-	return append([]string{svc.ClusterIP}, svc.ExternalIPs...), nil
+	copy(idx[len(svc.ClusterIPs):], svc.ExternalIPs)
+	return idx, nil
 }
 
 func svcNameNamespaceIndexFunc(obj interface{}) ([]string, error) {

plugin/kubernetes/external_test.go

@@ -105,7 +105,7 @@ var svcIndexExternal = map[string][]*object.Service{
 			Name:        "svc1",
 			Namespace:   "testns",
 			Type:        api.ServiceTypeClusterIP,
-			ClusterIP:   "10.0.0.1",
+			ClusterIPs:  []string{"10.0.0.1"},
 			ExternalIPs: []string{"1.2.3.4"},
 			Ports:       []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},
@@ -115,7 +115,7 @@ var svcIndexExternal = map[string][]*object.Service{
 			Name:        "svc6",
 			Namespace:   "testns",
 			Type:        api.ServiceTypeClusterIP,
-			ClusterIP:   "10.0.0.3",
+			ClusterIPs:  []string{"10.0.0.3"},
 			ExternalIPs: []string{"1:2::5"},
 			Ports:       []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},

plugin/kubernetes/handler_test.go

@@ -372,6 +372,30 @@ var dnsTestCases = []test.Case{
 			test.SOA("cluster.local.	5	IN	SOA	ns.dns.cluster.local. hostmaster.cluster.local. 1499347823 7200 1800 86400 5"),
 		},
 	},
+	// Dual Stack ClusterIP Services
+	{
+		Qname: "svc-dual-stack.testns.svc.cluster.local.", Qtype: dns.TypeA,
+		Rcode: dns.RcodeSuccess,
+		Answer: []dns.RR{
+			test.A("svc-dual-stack.testns.svc.cluster.local.	5	IN	A	10.0.0.3"),
+		},
+	},
+	{
+		Qname: "svc-dual-stack.testns.svc.cluster.local.", Qtype: dns.TypeAAAA,
+		Rcode: dns.RcodeSuccess,
+		Answer: []dns.RR{
+			test.AAAA("svc-dual-stack.testns.svc.cluster.local.	5	IN	AAAA	10::3"),
+		},
+	},
+	{
+		Qname: "svc-dual-stack.testns.svc.cluster.local.", Qtype: dns.TypeSRV,
+		Rcode: dns.RcodeSuccess,
+		Answer: []dns.RR{test.SRV("svc-dual-stack.testns.svc.cluster.local.	5	IN	SRV	0 50 80 svc-dual-stack.testns.svc.cluster.local.")},
+		Extra: []dns.RR{
+			test.A("svc-dual-stack.testns.svc.cluster.local.  5       IN      A       10.0.0.3"),
+			test.AAAA("svc-dual-stack.testns.svc.cluster.local.  5       IN      AAAA       10::3"),
+		},
+	},
 }
 
 func TestServeDNS(t *testing.T) {
@@ -539,10 +563,10 @@ func (APIConnServeTest) PodIndex(ip string) []*object.Pod {
 var svcIndex = map[string][]*object.Service{
 	"svc1.testns": {
 		{
-			Name:      "svc1",
-			Namespace: "testns",
-			Type:      api.ServiceTypeClusterIP,
-			ClusterIP: "10.0.0.1",
+			Name:       "svc1",
+			Namespace:  "testns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{"10.0.0.1"},
 			Ports: []api.ServicePort{
 				{Name: "http", Protocol: "tcp", Port: 80},
 			},
@@ -550,10 +574,10 @@ var svcIndex = map[string][]*object.Service{
 	},
 	"svcempty.testns": {
 		{
-			Name:      "svcempty",
-			Namespace: "testns",
-			Type:      api.ServiceTypeClusterIP,
-			ClusterIP: "10.0.0.1",
+			Name:       "svcempty",
+			Namespace:  "testns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{"10.0.0.1"},
 			Ports: []api.ServicePort{
 				{Name: "http", Protocol: "tcp", Port: 80},
 			},
@@ -561,10 +585,10 @@ var svcIndex = map[string][]*object.Service{
 	},
 	"svc6.testns": {
 		{
-			Name:      "svc6",
-			Namespace: "testns",
-			Type:      api.ServiceTypeClusterIP,
-			ClusterIP: "1234:abcd::1",
+			Name:       "svc6",
+			Namespace:  "testns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{"1234:abcd::1"},
 			Ports: []api.ServicePort{
 				{Name: "http", Protocol: "tcp", Port: 80},
 			},
@@ -572,10 +596,10 @@ var svcIndex = map[string][]*object.Service{
 	},
 	"hdls1.testns": {
 		{
-			Name:      "hdls1",
-			Namespace: "testns",
-			Type:      api.ServiceTypeClusterIP,
-			ClusterIP: api.ClusterIPNone,
+			Name:       "hdls1",
+			Namespace:  "testns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{api.ClusterIPNone},
 		},
 	},
 	"external.testns": {
@@ -602,23 +626,33 @@ var svcIndex = map[string][]*object.Service{
 	},
 	"hdlsprtls.testns": {
 		{
-			Name:      "hdlsprtls",
-			Namespace: "testns",
-			Type:      api.ServiceTypeClusterIP,
-			ClusterIP: api.ClusterIPNone,
+			Name:       "hdlsprtls",
+			Namespace:  "testns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{api.ClusterIPNone},
 		},
 	},
 	"svc1.unexposedns": {
 		{
-			Name:      "svc1",
-			Namespace: "unexposedns",
-			Type:      api.ServiceTypeClusterIP,
-			ClusterIP: "10.0.0.2",
+			Name:       "svc1",
+			Namespace:  "unexposedns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{"10.0.0.2"},
 			Ports: []api.ServicePort{
 				{Name: "http", Protocol: "tcp", Port: 80},
 			},
 		},
 	},
+	"svc-dual-stack.testns": {
+		{
+			Name:       "svc-dual-stack",
+			Namespace:  "testns",
+			Type:       api.ServiceTypeClusterIP,
+			ClusterIPs: []string{"10.0.0.3", "10::3"}, Ports: []api.ServicePort{
+				{Name: "http", Protocol: "tcp", Port: 80},
+			},
+		},
+	},
 }
 
 func (APIConnServeTest) SvcIndex(s string) []*object.Service { return svcIndex[s] }

plugin/kubernetes/informer_test.go

 package kubernetes
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/coredns/coredns/plugin/kubernetes/object"
@@ -21,11 +22,19 @@ func TestDefaultProcessor(t *testing.T) {
 func testProcessor(t *testing.T, processor cache.ProcessFunc, idx cache.Indexer) {
 	obj := &api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: "service1", Namespace: "test1"},
-		Spec:       api.ServiceSpec{ClusterIP: "1.2.3.4", Ports: []api.ServicePort{{Port: 80}}},
+		Spec: api.ServiceSpec{
+			ClusterIP:  "1.2.3.4",
+			ClusterIPs: []string{"1.2.3.4"},
+			Ports:      []api.ServicePort{{Port: 80}},
+		},
 	}
 	obj2 := &api.Service{
 		ObjectMeta: metav1.ObjectMeta{Name: "service2", Namespace: "test1"},
-		Spec:       api.ServiceSpec{ClusterIP: "5.6.7.8", Ports: []api.ServicePort{{Port: 80}}},
+		Spec: api.ServiceSpec{
+			ClusterIP:  "5.6.7.8",
+			ClusterIPs: []string{"5.6.7.8"},
+			Ports:      []api.ServicePort{{Port: 80}},
+		},
 	}
 
 	// Add the objects
@@ -47,8 +56,8 @@ func testProcessor(t *testing.T, processor cache.ProcessFunc, idx cache.Indexer)
 	if !ok {
 		t.Fatal("object in index was incorrect type")
 	}
-	if svc.ClusterIP != obj.Spec.ClusterIP {
-		t.Fatalf("expected %v, got %v", obj.Spec.ClusterIP, svc.ClusterIP)
+	if fmt.Sprintf("%v", svc.ClusterIPs) != fmt.Sprintf("%v", obj.Spec.ClusterIPs) {
+		t.Fatalf("expected '%v', got '%v'", obj.Spec.ClusterIPs, svc.ClusterIPs)
 	}
 
 	// Update an object
@@ -71,8 +80,8 @@ func testProcessor(t *testing.T, processor cache.ProcessFunc, idx cache.Indexer)
 	if !ok {
 		t.Fatal("object in index was incorrect type")
 	}
-	if svc.ClusterIP != obj.Spec.ClusterIP {
-		t.Fatalf("expected %v, got %v", obj.Spec.ClusterIP, svc.ClusterIP)
+	if fmt.Sprintf("%v", svc.ClusterIPs) != fmt.Sprintf("%v", obj.Spec.ClusterIPs) {
+		t.Fatalf("expected '%v', got '%v'", obj.Spec.ClusterIPs, svc.ClusterIPs)
 	}
 
 	// Delete an object

plugin/kubernetes/kubernetes.go

@@ -433,8 +433,7 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
 
 		// If "ignore empty_service" option is set and no endpoints exist, return NXDOMAIN unless
 		// it's a headless or externalName service (covered below).
-		if k.opts.ignoreEmptyService && svc.ClusterIP != api.ClusterIPNone && svc.Type != api.ServiceTypeExternalName {
-			// serve NXDOMAIN if no endpoint is able to answer
+		if k.opts.ignoreEmptyService && svc.Type != api.ServiceTypeExternalName && !svc.Headless() { // serve NXDOMAIN if no endpoint is able to answer
 			podsCount := 0
 			for _, ep := range endpointsListFunc() {
 				for _, eps := range ep.Subsets {
@@ -447,8 +446,20 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
 			}
 		}
 
+		// External service
+		if svc.Type == api.ServiceTypeExternalName {
+			s := msg.Service{Key: strings.Join([]string{zonePath, Svc, svc.Namespace, svc.Name}, "/"), Host: svc.ExternalName, TTL: k.ttl}
+			if t, _ := s.HostType(); t == dns.TypeCNAME {
+				s.Key = strings.Join([]string{zonePath, Svc, svc.Namespace, svc.Name}, "/")
+				services = append(services, s)
+
+				err = nil
+			}
+			continue
+		}
+
 		// Endpoint query or headless service
-		if svc.ClusterIP == api.ClusterIPNone || r.endpoint != "" {
+		if svc.Headless() || r.endpoint != "" {
 			if endpointsList == nil {
 				endpointsList = endpointsListFunc()
 			}
@@ -485,18 +496,6 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
 			continue
 		}
 
-		// External service
-		if svc.Type == api.ServiceTypeExternalName {
-			s := msg.Service{Key: strings.Join([]string{zonePath, Svc, svc.Namespace, svc.Name}, "/"), Host: svc.ExternalName, TTL: k.ttl}
-			if t, _ := s.HostType(); t == dns.TypeCNAME {
-				s.Key = strings.Join([]string{zonePath, Svc, svc.Namespace, svc.Name}, "/")
-				services = append(services, s)
-
-				err = nil
-			}
-			continue
-		}
-
 		// ClusterIP service
 		for _, p := range svc.Ports {
 			if !(match(r.port, p.Name) && match(r.protocol, string(p.Protocol))) {
@@ -505,10 +504,11 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
 
 			err = nil
 
-			s := msg.Service{Host: svc.ClusterIP, Port: int(p.Port), TTL: k.ttl}
-			s.Key = strings.Join([]string{zonePath, Svc, svc.Namespace, svc.Name}, "/")
-
-			services = append(services, s)
+			for _, ip := range svc.ClusterIPs {
+				s := msg.Service{Host: ip, Port: int(p.Port), TTL: k.ttl}
+				s.Key = strings.Join([]string{zonePath, Svc, svc.Namespace, svc.Name}, "/")
+				services = append(services, s)
+			}
 		}
 	}
 	return services, err

plugin/kubernetes/kubernetes_test.go

@@ -71,17 +71,25 @@ func (APIConnServiceTest) Modified() int64                           { return 0
 func (APIConnServiceTest) SvcIndex(string) []*object.Service {
 	svcs := []*object.Service{
 		{
-			Name:      "svc1",
-			Namespace: "testns",
-			ClusterIP: "10.0.0.1",
+			Name:       "svc1",
+			Namespace:  "testns",
+			ClusterIPs: []string{"10.0.0.1"},
 			Ports: []api.ServicePort{
 				{Name: "http", Protocol: "tcp", Port: 80},
 			},
 		},
 		{
-			Name:      "hdls1",
-			Namespace: "testns",
-			ClusterIP: api.ClusterIPNone,
+			Name:       "svc-dual-stack",
+			Namespace:  "testns",
+			ClusterIPs: []string{"10.0.0.2", "10::2"},
+			Ports: []api.ServicePort{
+				{Name: "http", Protocol: "tcp", Port: 80},
+			},
+		},
+		{
+			Name:       "hdls1",
+			Namespace:  "testns",
+			ClusterIPs: []string{api.ClusterIPNone},
 		},
 		{
 			Name:         "external",
@@ -99,17 +107,25 @@ func (APIConnServiceTest) SvcIndex(string) []*object.Service {
 func (APIConnServiceTest) ServiceList() []*object.Service {
 	svcs := []*object.Service{
 		{
-			Name:      "svc1",
-			Namespace: "testns",
-			ClusterIP: "10.0.0.1",
+			Name:       "svc1",
+			Namespace:  "testns",
+			ClusterIPs: []string{"10.0.0.1"},
 			Ports: []api.ServicePort{
 				{Name: "http", Protocol: "tcp", Port: 80},
 			},
 		},
 		{
-			Name:      "hdls1",
-			Namespace: "testns",
-			ClusterIP: api.ClusterIPNone,
+			Name:       "svc-dual-stack",
+			Namespace:  "testns",
+			ClusterIPs: []string{"10.0.0.2", "10::2"},
+			Ports: []api.ServicePort{
+				{Name: "http", Protocol: "tcp", Port: 80},
+			},
+		},
+		{
+			Name:       "hdls1",
+			Namespace:  "testns",
+			ClusterIPs: []string{api.ClusterIPNone},
 		},
 		{
 			Name:         "external",
@@ -256,19 +272,29 @@ func TestServices(t *testing.T) {
 	type svcTest struct {
 		qname  string
 		qtype  uint16
-		answer svcAns
+		answer []svcAns
 	}
 	tests := []svcTest{
 		// Cluster IP Services
-		{qname: "svc1.testns.svc.interwebs.test.", qtype: dns.TypeA, answer: svcAns{host: "10.0.0.1", key: "/" + coredns + "/test/interwebs/svc/testns/svc1"}},
-		{qname: "_http._tcp.svc1.testns.svc.interwebs.test.", qtype: dns.TypeSRV, answer: svcAns{host: "10.0.0.1", key: "/" + coredns + "/test/interwebs/svc/testns/svc1"}},
-		{qname: "ep1a.svc1.testns.svc.interwebs.test.", qtype: dns.TypeA, answer: svcAns{host: "172.0.0.1", key: "/" + coredns + "/test/interwebs/svc/testns/svc1/ep1a"}},
+		{qname: "svc1.testns.svc.interwebs.test.", qtype: dns.TypeA, answer: []svcAns{{host: "10.0.0.1", key: "/" + coredns + "/test/interwebs/svc/testns/svc1"}}},
+		{qname: "_http._tcp.svc1.testns.svc.interwebs.test.", qtype: dns.TypeSRV, answer: []svcAns{{host: "10.0.0.1", key: "/" + coredns + "/test/interwebs/svc/testns/svc1"}}},
+		{qname: "ep1a.svc1.testns.svc.interwebs.test.", qtype: dns.TypeA, answer: []svcAns{{host: "172.0.0.1", key: "/" + coredns + "/test/interwebs/svc/testns/svc1/ep1a"}}},
+
+		// Dual-Stack Cluster IP Service
+		{
+			qname: "_http._tcp.svc-dual-stack.testns.svc.interwebs.test.",
+			qtype: dns.TypeSRV,
+			answer: []svcAns{
+				{host: "10.0.0.2", key: "/" + coredns + "/test/interwebs/svc/testns/svc-dual-stack"},
+				{host: "10::2", key: "/" + coredns + "/test/interwebs/svc/testns/svc-dual-stack"},
+			},
+		},
 
 		// External Services
-		{qname: "external.testns.svc.interwebs.test.", qtype: dns.TypeCNAME, answer: svcAns{host: "coredns.io", key: "/" + coredns + "/test/interwebs/svc/testns/external"}},
+		{qname: "external.testns.svc.interwebs.test.", qtype: dns.TypeCNAME, answer: []svcAns{{host: "coredns.io", key: "/" + coredns + "/test/interwebs/svc/testns/external"}}},
 
 		// Headless Services
-		{qname: "hdls1.testns.svc.interwebs.test.", qtype: dns.TypeA, answer: svcAns{host: "172.0.0.2", key: "/" + coredns + "/test/interwebs/svc/testns/hdls1/172-0-0-2"}},
+		{qname: "hdls1.testns.svc.interwebs.test.", qtype: dns.TypeA, answer: []svcAns{{host: "172.0.0.2", key: "/" + coredns + "/test/interwebs/svc/testns/hdls1/172-0-0-2"}}},
 	}
 
 	for i, test := range tests {
@@ -281,16 +307,18 @@ func TestServices(t *testing.T) {
 			t.Errorf("Test %d: got error '%v'", i, e)
 			continue
 		}
-		if len(svcs) != 1 {
-			t.Errorf("Test %d, expected 1 answer, got %v", i, len(svcs))
+		if len(svcs) != len(test.answer) {
+			t.Errorf("Test %d, expected %v answer, got %v", i, len(test.answer), len(svcs))
 			continue
 		}
 
-		if test.answer.host != svcs[0].Host {
-			t.Errorf("Test %d, expected host '%v', got '%v'", i, test.answer.host, svcs[0].Host)
-		}
-		if test.answer.key != svcs[0].Key {
-			t.Errorf("Test %d, expected key '%v', got '%v'", i, test.answer.key, svcs[0].Key)
+		for j := range svcs {
+			if test.answer[j].host != svcs[j].Host {
+				t.Errorf("Test %d, expected host '%v', got '%v'", i, test.answer[j].host, svcs[j].Host)
+			}
+			if test.answer[j].key != svcs[j].Key {
+				t.Errorf("Test %d, expected key '%v', got '%v'", i, test.answer[j].key, svcs[j].Key)
+			}
 		}
 	}
 }

plugin/kubernetes/ns.go

@@ -5,7 +5,6 @@ import (
 	"strings"
 
 	"github.com/miekg/dns"
-	api "k8s.io/api/core/v1"
 )
 
 func isDefaultNS(name, zone string) bool {
@@ -37,7 +36,7 @@ func (k *Kubernetes) nsAddrs(external bool, zone string) []dns.RR {
 					continue
 				}
 				svcName := strings.Join([]string{svc.Name, svc.Namespace, Svc, zone}, ".")
-				if svc.ClusterIP == api.ClusterIPNone {
+				if svc.Headless() {
 					// For a headless service, use the endpoints IPs
 					for _, s := range endpoint.Subsets {
 						for _, a := range s.Addresses {
@@ -46,8 +45,10 @@ func (k *Kubernetes) nsAddrs(external bool, zone string) []dns.RR {
 						}
 					}
 				} else {
-					svcNames = append(svcNames, svcName)
-					svcIPs = append(svcIPs, net.ParseIP(svc.ClusterIP))
+					for _, clusterIP := range svc.ClusterIPs {
+						svcNames = append(svcNames, svcName)
+						svcIPs = append(svcIPs, net.ParseIP(clusterIP))
+					}
 				}
 			}
 		}

plugin/kubernetes/ns_test.go

@@ -37,19 +37,19 @@ func (a APIConnTest) SvcIndex(s string) []*object.Service {
 func (APIConnTest) ServiceList() []*object.Service {
 	svcs := []*object.Service{
 		{
-			Name:      "dns-service",
-			Namespace: "kube-system",
-			ClusterIP: "10.0.0.111",
+			Name:       "dns-service",
+			Namespace:  "kube-system",
+			ClusterIPs: []string{"10.0.0.111"},
 		},
 		{
-			Name:      "hdls-dns-service",
-			Namespace: "kube-system",
-			ClusterIP: api.ClusterIPNone,
+			Name:       "hdls-dns-service",
+			Namespace:  "kube-system",
+			ClusterIPs: []string{api.ClusterIPNone},
 		},
 		{
-			Name:      "dns6-service",
-			Namespace: "kube-system",
-			ClusterIP: "10::111",
+			Name:       "dns6-service",
+			Namespace:  "kube-system",
+			ClusterIPs: []string{"10::111"},
 		},
 	}
 	return svcs

plugin/kubernetes/object/metrics.go

@@ -67,7 +67,7 @@ func (l *EndpointLatencyRecorder) record() {
 	// don't change very often (comparing to much more frequent endpoints changes), cases when this method
 	// will return wrong answer should be relatively rare. Because of that we intentionally accept this
 	// flaw to keep the solution simple.
-	isHeadless := len(l.Services) == 1 && l.Services[0].ClusterIP == api.ClusterIPNone
+	isHeadless := len(l.Services) == 1 && l.Services[0].Headless()
 
 	if !isHeadless || l.TT.IsZero() {
 		return

plugin/kubernetes/object/service.go

@@ -15,7 +15,7 @@ type Service struct {
 	Name         string
 	Namespace    string
 	Index        string
-	ClusterIP    string
+	ClusterIPs   []string
 	Type         api.ServiceType
 	ExternalName string
 	Ports        []api.ServicePort
@@ -40,13 +40,19 @@ func ToService(obj meta.Object) (meta.Object, error) {
 		Name:         svc.GetName(),
 		Namespace:    svc.GetNamespace(),
 		Index:        ServiceKey(svc.GetName(), svc.GetNamespace()),
-		ClusterIP:    svc.Spec.ClusterIP,
 		Type:         svc.Spec.Type,
 		ExternalName: svc.Spec.ExternalName,
 
 		ExternalIPs: make([]string, len(svc.Status.LoadBalancer.Ingress)+len(svc.Spec.ExternalIPs)),
 	}
 
+	if len(svc.Spec.ClusterIPs) > 0 {
+		s.ClusterIPs = make([]string, len(svc.Spec.ClusterIPs))
+		copy(s.ClusterIPs, svc.Spec.ClusterIPs)
+	} else {
+		s.ClusterIPs = []string{svc.Spec.ClusterIP}
+	}
+
 	if len(svc.Spec.Ports) == 0 {
 		// Add sentinel if there are no ports.
 		s.Ports = []api.ServicePort{{Port: -1}}
@@ -70,6 +76,11 @@ func ToService(obj meta.Object) (meta.Object, error) {
 	return s, nil
 }
 
+// Headless returns true if the service is headless
+func (s *Service) Headless() bool {
+	return s.ClusterIPs[0] == api.ClusterIPNone
+}
+
 var _ runtime.Object = &Service{}
 
 // DeepCopyObject implements the ObjectKind interface.
@@ -79,12 +90,13 @@ func (s *Service) DeepCopyObject() runtime.Object {
 		Name:         s.Name,
 		Namespace:    s.Namespace,
 		Index:        s.Index,
-		ClusterIP:    s.ClusterIP,
 		Type:         s.Type,
 		ExternalName: s.ExternalName,
+		ClusterIPs:   make([]string, len(s.ClusterIPs)),
 		Ports:        make([]api.ServicePort, len(s.Ports)),
 		ExternalIPs:  make([]string, len(s.ExternalIPs)),
 	}
+	copy(s1.ClusterIPs, s.ClusterIPs)
 	copy(s1.Ports, s.Ports)
 	copy(s1.ExternalIPs, s.ExternalIPs)
 	return s1

plugin/kubernetes/reverse_test.go

@@ -30,10 +30,10 @@ func (APIConnReverseTest) SvcIndex(svc string) []*object.Service {
 	}
 	svcs := []*object.Service{
 		{
-			Name:      "svc1",
-			Namespace: "testns",
-			ClusterIP: "192.168.1.100",
-			Ports:     []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
+			Name:       "svc1",
+			Namespace:  "testns",
+			ClusterIPs: []string{"192.168.1.100"},
+			Ports:      []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},
 	}
 	return svcs
@@ -46,10 +46,10 @@ func (APIConnReverseTest) SvcIndexReverse(ip string) []*object.Service {
 	}
 	svcs := []*object.Service{
 		{
-			Name:      "svc1",
-			Namespace: "testns",
-			ClusterIP: "192.168.1.100",
-			Ports:     []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
+			Name:       "svc1",
+			Namespace:  "testns",
+			ClusterIPs: []string{"192.168.1.100"},
+			Ports:      []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},
 	}
 	return svcs

plugin/kubernetes/xfr.go

@@ -50,13 +50,16 @@ func (k *Kubernetes) Transfer(zone string, serial uint32) (<-chan []dns.RR, erro
 			switch svc.Type {
 
 			case api.ServiceTypeClusterIP, api.ServiceTypeNodePort, api.ServiceTypeLoadBalancer:
-				clusterIP := net.ParseIP(svc.ClusterIP)
+				clusterIP := net.ParseIP(svc.ClusterIPs[0])
 				if clusterIP != nil {
-					s := msg.Service{Host: svc.ClusterIP, TTL: k.ttl}
-					s.Key = strings.Join(svcBase, "/")
+					var host string
+					for _, ip := range svc.ClusterIPs {
+						s := msg.Service{Host: ip, TTL: k.ttl}
+						s.Key = strings.Join(svcBase, "/")
 
-					// Change host from IP to Name for SRV records
-					host := emitAddressRecord(ch, s)
+						// Change host from IP to Name for SRV records
+						host = emitAddressRecord(ch, s)
+					}
 
 					for _, p := range svc.Ports {
 						s := msg.Service{Host: host, Port: int(p.Port), TTL: k.ttl}

plugin/kubernetes/xfr_test.go

@@ -113,6 +113,10 @@ hdls1.testns.svc.cluster.local.	5	IN	AAAA	5678:abcd::2
 _http._tcp.hdls1.testns.svc.cluster.local.	5	IN	SRV	0 16 80 5678-abcd--2.hdls1.testns.svc.cluster.local.
 hdlsprtls.testns.svc.cluster.local.	5	IN	A	172.0.0.20
 172-0-0-20.hdlsprtls.testns.svc.cluster.local.	5	IN	A	172.0.0.20
+svc-dual-stack.testns.svc.cluster.local.	5	IN	A	10.0.0.3
+svc-dual-stack.testns.svc.cluster.local.	5	IN	AAAA	10::3
+svc-dual-stack.testns.svc.cluster.local.	5	IN	SRV	0 100 80 svc-dual-stack.testns.svc.cluster.local.
+_http._tcp.svc-dual-stack.testns.svc.cluster.local.	5	IN	SRV	0 100 80 svc-dual-stack.testns.svc.cluster.local.
 svc1.testns.svc.cluster.local.	5	IN	A	10.0.0.1
 svc1.testns.svc.cluster.local.	5	IN	SRV	0 100 80 svc1.testns.svc.cluster.local.
 _http._tcp.svc1.testns.svc.cluster.local.	5	IN	SRV	0 100 80 svc1.testns.svc.cluster.local.