Merge pull request #8501 from ArtfulCoder/kubelet_svc_subdomain

Support old and new style dns service names.

cluster/addons/dns/README.md

@@ -13,6 +13,11 @@ crashes or scheduling changes).  This maps well to DNS, which has a long
 history of clients that, on purpose or on accident, do not respect DNS TTLs
 (see previous remark about Pod IPs changing).
 
+## DNS Name format for Services
+Services get a DNS name with the format my-svc.my-namespace.svc.cluster.local
+'svc' should not be used a namespace label to avoid conflicts.
+The old format of my-svc.my-namespace.cluster.local has been deprecated. 
+
 ## How do I find the DNS server?
 The DNS server itself runs as a Kubernetes Service.  This gives it a stable IP
 address.  When you run the SkyDNS service, you want to assign a static IP to use for
@@ -35,12 +40,12 @@ example, see `cluster/gce/config-default.sh`.
 ```shell
 ENABLE_CLUSTER_DNS=true
 DNS_SERVER_IP="10.0.0.10"
-DNS_DOMAIN="kubernetes.local"
+DNS_DOMAIN="cluster.local"
 DNS_REPLICAS=1
 ```
 
 This enables DNS with a DNS Service IP of `10.0.0.10` and a local domain of
-`kubernetes.local`, served by a single copy of SkyDNS.
+`cluster.local`, served by a single copy of SkyDNS.
 
 If you are not using a supported cluster setup, you will have to replicate some
 of this yourself.  First, each kubelet needs to run with the following flags

cluster/addons/dns/kube2sky/Makefile

@@ -4,7 +4,7 @@
 
 .PHONY: all kube2sky container push clean test
 
-TAG = 1.5
+TAG = 1.6
 PREFIX = gcr.io/google_containers
 
 all: container

cluster/addons/dns/kube2sky/kube2sky.go

@@ -204,10 +204,14 @@ func newKubeClient() (*kclient.Client, error) {
 	return kclient.New(config)
 }
 
-func buildNameString(service, namespace, domain string) string {
+func buildOldNameString(service, namespace, domain string) string {
 	return fmt.Sprintf("%s.%s.%s.", service, namespace, domain)
 }
 
+func buildNewServiceNameString(service, namespace, domain string) string {
+	return fmt.Sprintf("%s.%s.svc.%s.", service, namespace, domain)
+}
+
 // Returns a cache.ListWatch that gets all changes to services.
 func createServiceLW(kubeClient *kclient.Client) *cache.ListWatch {
 	return cache.NewListWatchFromClient(kubeClient, "services", kapi.NamespaceAll, kSelector.Everything())
@@ -215,15 +219,20 @@ func createServiceLW(kubeClient *kclient.Client) *cache.ListWatch {
 
 func (ks *kube2sky) newService(obj interface{}) {
 	if s, ok := obj.(*kapi.Service); ok {
-		name := buildNameString(s.Name, s.Namespace, ks.domain)
+		//TODO(artfulcoder) stop adding and deleting old-format string for service
+		name := buildOldNameString(s.Name, s.Namespace, ks.domain)
 		ks.mutateEtcdOrDie(func() error { return ks.addDNS(name, s) })
+		name1 := buildNewServiceNameString(s.Name, s.Namespace, ks.domain)
+		ks.mutateEtcdOrDie(func() error { return ks.addDNS(name1, s) })
 	}
 }
 
 func (ks *kube2sky) removeService(obj interface{}) {
 	if s, ok := obj.(*kapi.Service); ok {
-		name := buildNameString(s.Name, s.Namespace, ks.domain)
+		name := buildOldNameString(s.Name, s.Namespace, ks.domain)
 		ks.mutateEtcdOrDie(func() error { return ks.removeDNS(name) })
+		name1 := buildNewServiceNameString(s.Name, s.Namespace, ks.domain)
+		ks.mutateEtcdOrDie(func() error { return ks.removeDNS(name1) })
 	}
 }
 

cluster/addons/dns/kube2sky/kube2sky_test.go

@@ -49,8 +49,9 @@ func (ec *fakeEtcdClient) Delete(path string, recursive bool) (*etcd.Response, e
 }
 
 const (
-	testDomain = "cluster.local"
-	basePath   = "/skydns/local/cluster"
+	testDomain       = "cluster.local"
+	basePath         = "/skydns/local/cluster"
+	serviceSubDomain = "svc"
 )
 
 func newKube2Sky(ec etcdClient) *kube2sky {
@@ -61,25 +62,12 @@ func newKube2Sky(ec etcdClient) *kube2sky {
 	}
 }
 
-func TestAddNoServiceIP(t *testing.T) {
-	const (
-		testService   = "testService"
-		testNamespace = "default"
-	)
-	ec := &fakeEtcdClient{make(map[string]string)}
-	k2s := newKube2Sky(ec)
-	service := kapi.Service{
-		ObjectMeta: kapi.ObjectMeta{
-			Name:      testNamespace,
-			Namespace: testNamespace,
-		},
-	}
-	k2s.newService(&service)
-	assert.Empty(t, ec.writes)
+func getEtcdOldStylePath(name, namespace string) string {
+	return path.Join(basePath, namespace, name)
 }
 
-func getEtcdPath(name, namespace string) string {
-	return path.Join(basePath, namespace, name)
+func getEtcdNewStylePath(name, namespace string) string {
+	return path.Join(basePath, serviceSubDomain, namespace, name)
 }
 
 type hostPort struct {
@@ -100,6 +88,39 @@ func getHostPortFromString(data string) (*hostPort, error) {
 	return &res, err
 }
 
+func assertDnsServiceEntryInEtcd(t *testing.T, ec *fakeEtcdClient, serviceName, namespace string, expectedHostPort *hostPort) {
+	oldStyleKey := getEtcdOldStylePath(serviceName, namespace)
+	val, exists := ec.writes[oldStyleKey]
+	require.True(t, exists)
+	actualHostPort, err := getHostPortFromString(val)
+	require.NoError(t, err)
+	assert.Equal(t, actualHostPort, expectedHostPort)
+
+	newStyleKey := getEtcdNewStylePath(serviceName, namespace)
+	val, exists = ec.writes[newStyleKey]
+	require.True(t, exists)
+	actualHostPort, err = getHostPortFromString(val)
+	require.NoError(t, err)
+	assert.Equal(t, actualHostPort, expectedHostPort)
+}
+
+func TestHeadlessService(t *testing.T) {
+	const (
+		testService   = "testService"
+		testNamespace = "default"
+	)
+	ec := &fakeEtcdClient{make(map[string]string)}
+	k2s := newKube2Sky(ec)
+	service := kapi.Service{
+		ObjectMeta: kapi.ObjectMeta{
+			Name:      testNamespace,
+			Namespace: testNamespace,
+		},
+	}
+	k2s.newService(&service)
+	assert.Empty(t, ec.writes)
+}
+
 func TestAddSinglePortService(t *testing.T) {
 	const (
 		testService   = "testService"
@@ -122,13 +143,8 @@ func TestAddSinglePortService(t *testing.T) {
 		},
 	}
 	k2s.newService(&service)
-	expectedKey := getEtcdPath(testService, testNamespace)
 	expectedValue := getHostPort(&service)
-	val, exists := ec.writes[expectedKey]
-	require.True(t, exists)
-	actualValue, err := getHostPortFromString(val)
-	require.NoError(t, err)
-	assert.Equal(t, actualValue, expectedValue)
+	assertDnsServiceEntryInEtcd(t, ec, testService, testNamespace, expectedValue)
 }
 
 func TestUpdateSinglePortService(t *testing.T) {
@@ -153,16 +169,11 @@ func TestUpdateSinglePortService(t *testing.T) {
 		},
 	}
 	k2s.newService(&service)
-	assert.Len(t, ec.writes, 1)
+	assert.Len(t, ec.writes, 2)
 	service.Spec.PortalIP = "0.0.0.0"
 	k2s.newService(&service)
-	expectedKey := getEtcdPath(testService, testNamespace)
 	expectedValue := getHostPort(&service)
-	val, exists := ec.writes[expectedKey]
-	require.True(t, exists)
-	actualValue, err := getHostPortFromString(val)
-	require.NoError(t, err)
-	assert.Equal(t, actualValue, expectedValue)
+	assertDnsServiceEntryInEtcd(t, ec, testService, testNamespace, expectedValue)
 }
 
 func TestDeleteSinglePortService(t *testing.T) {
@@ -188,7 +199,9 @@ func TestDeleteSinglePortService(t *testing.T) {
 	}
 	// Add the service
 	k2s.newService(&service)
-	assert.Len(t, ec.writes, 1)
+	// two entries should get created, one with the svc subdomain (new-style)
+	// , and one without the svc subdomain (old-style)
+	assert.Len(t, ec.writes, 2)
 	// Delete the service
 	k2s.removeService(&service)
 	assert.Empty(t, ec.writes)

cluster/addons/dns/skydns-rc.yaml.in

@@ -30,7 +30,7 @@ spec:
         - -initial-cluster-token
         - skydns-etcd
       - name: kube2sky
-        image: gcr.io/google_containers/kube2sky:1.5
+        image: gcr.io/google_containers/kube2sky:1.6
         args:
         # command = "/kube2sky"
         - -domain={{ pillar['dns_domain'] }}

test/e2e/dns.go

@@ -72,6 +72,8 @@ var _ = Describe("DNS", func() {
 		// TODO: Spin up a separate test service and test that dns works for that service.
 		namesToResolve := []string{
 			"kubernetes-ro.default",
+			"kubernetes-ro.default.svc",
+			"kubernetes-ro.default.svc.cluster.local",
 			"kubernetes-ro.default.cluster.local",
 			"google.com",
 		}