Specify hostname, subdomain via annotation on podspec.

The hostname is a DNS A record, if the subdomain maps to a service name
in the same namespace

cluster/addons/dns/kube2sky/Changelog

@@ -1,3 +1,7 @@
+## Version 1.14 (Mar 4 2016 Abhishek Shah <abshah@google.com>)
+- If Endpoint has hostnames-map annotation (endpoints.net.beta.kubernetes.io/hostnames-map),
+  the hostnames supplied via the annotation will be used to generate A Records for Headless Service.
+
 ## Version 1.13 (Mar 1 2016 Prashanth.B <beeps@google.com>)
 - Synchronously wait for the Kubernetes service at startup.
 - Add a SIGTERM/SIGINT handler.

cluster/addons/dns/kube2sky/Makefile

@@ -18,7 +18,7 @@
 
 .PHONY: all kube2sky container push clean test
 
-TAG = 1.13
+TAG = 1.14
 PREFIX = gcr.io/google_containers
 
 all: container

cluster/addons/dns/kube2sky/kube2sky.go

@@ -37,6 +37,7 @@ import (
 	skymsg "github.com/skynetservices/skydns/msg"
 	flag "github.com/spf13/pflag"
 	kapi "k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/endpoints"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	kcache "k8s.io/kubernetes/pkg/client/cache"
 	"k8s.io/kubernetes/pkg/client/restclient"
@@ -46,6 +47,7 @@ import (
 	kselector "k8s.io/kubernetes/pkg/fields"
 	etcdutil "k8s.io/kubernetes/pkg/storage/etcd/util"
 	"k8s.io/kubernetes/pkg/util"
+	"k8s.io/kubernetes/pkg/util/validation"
 	"k8s.io/kubernetes/pkg/util/wait"
 )
 
@@ -159,14 +161,28 @@ func getSkyMsg(ip string, port int) *skymsg.Service {
 }
 
 func (ks *kube2sky) generateRecordsForHeadlessService(subdomain string, e *kapi.Endpoints, svc *kapi.Service) error {
+	glog.V(4).Infof("Endpoints Annotations: %v", e.Annotations)
 	for idx := range e.Subsets {
 		for subIdx := range e.Subsets[idx].Addresses {
-			b, err := json.Marshal(getSkyMsg(e.Subsets[idx].Addresses[subIdx].IP, 0))
+			endpointIP := e.Subsets[idx].Addresses[subIdx].IP
+			b, err := json.Marshal(getSkyMsg(endpointIP, 0))
 			if err != nil {
 				return err
 			}
 			recordValue := string(b)
 			recordLabel := getHash(recordValue)
+			if serializedPodHostnames := e.Annotations[endpoints.PodHostnamesAnnotation]; len(serializedPodHostnames) > 0 {
+				podHostnames := map[string]endpoints.HostRecord{}
+				err := json.Unmarshal([]byte(serializedPodHostnames), &podHostnames)
+				if err != nil {
+					return err
+				}
+				if hostRecord, exists := podHostnames[string(endpointIP)]; exists {
+					if validation.IsDNS1123Label(hostRecord.HostName) {
+						recordLabel = hostRecord.HostName
+					}
+				}
+			}
 			recordKey := buildDNSNameString(subdomain, recordLabel)
 
 			glog.V(2).Infof("Setting DNS record: %v -> %q\n", recordKey, recordValue)

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

@@ -47,7 +47,7 @@ spec:
         - name: etcd-storage
           mountPath: /var/etcd/data
       - name: kube2sky
-        image: gcr.io/google_containers/kube2sky:1.13
+        image: gcr.io/google_containers/kube2sky:1.14
         resources:
           # TODO: Set memory limits when we've profiled the container for large
           # clusters, then set request = limit to keep this container in