Allow cloud providers to return a node identifier different from the hostname

cmd/kubelet/app/server.go

@@ -565,7 +565,27 @@ func SimpleKubelet(client *client.Client,
 // Eventually, #2 will be replaced with instances of #3
 func RunKubelet(kcfg *KubeletConfig, builder KubeletBuilder) error {
 	kcfg.Hostname = nodeutil.GetHostname(kcfg.HostnameOverride)
-	kcfg.NodeName = kcfg.Hostname
+
+	if kcfg.NodeName == "" {
+		// Query the cloud provider for our node name, default to Hostname
+		nodeName := kcfg.Hostname
+		if kcfg.Cloud != nil {
+			var err error
+			instances, ok := kcfg.Cloud.Instances()
+			if !ok {
+				return fmt.Errorf("failed to get instances from cloud provider")
+			}
+
+			nodeName, err = instances.CurrentNodeName(kcfg.Hostname)
+			if err != nil {
+				return fmt.Errorf("error fetching current instance name from cloud provider: %v", err)
+			}
+
+			glog.V(2).Infof("cloud provider determined current node name to be %s", nodeName)
+		}
+
+		kcfg.NodeName = nodeName
+	}
 
 	eventBroadcaster := record.NewBroadcaster()
 	kcfg.Recorder = eventBroadcaster.NewRecorder(api.EventSource{Component: "kubelet", Host: kcfg.NodeName})

pkg/cloudprovider/aws/aws.go

@@ -234,6 +234,10 @@ func (self *AWSCloud) AddSSHKeyToAllInstances(user string, keyData []byte) error
 	return errors.New("unimplemented")
 }
 
+func (a *AWSCloud) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 // Implementation of EC2.Instances
 func (self *awsSdkEC2) DescribeInstances(request *ec2.DescribeInstancesInput) ([]*ec2.Instance, error) {
 	// Instances are paged

pkg/cloudprovider/cloud.go

@@ -111,6 +111,9 @@ type Instances interface {
 	// AddSSHKeyToAllInstances adds an SSH public key as a legal identity for all instances
 	// expected format for the key is standard ssh-keygen format: <protocol> <blob>
 	AddSSHKeyToAllInstances(user string, keyData []byte) error
+	// Returns the name of the node we are currently running on
+	// On most clouds (e.g. GCE) this is the hostname, so we provide the hostname
+	CurrentNodeName(hostname string) (string, error)
 }
 
 // Route is a representation of an advanced routing rule.

pkg/cloudprovider/fake/fake.go

@@ -149,6 +149,11 @@ func (f *FakeCloud) AddSSHKeyToAllInstances(user string, keyData []byte) error {
 	return errors.New("unimplemented")
 }
 
+// Implementation of Instances.CurrentNodeName
+func (f *FakeCloud) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 // NodeAddresses is a test-spy implementation of Instances.NodeAddresses.
 // It adds an entry "node-addresses" into the internal method call record.
 func (f *FakeCloud) NodeAddresses(instance string) ([]api.NodeAddress, error) {

pkg/cloudprovider/gce/gce.go

@@ -483,6 +483,11 @@ func (gce *GCECloud) getInstanceByName(name string) (*compute.Instance, error) {
 	return res, nil
 }
 
+// Implementation of Instances.CurrentNodeName
+func (gce *GCECloud) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 func (gce *GCECloud) AddSSHKeyToAllInstances(user string, keyData []byte) error {
 	return wait.Poll(2*time.Second, 30*time.Second, func() (bool, error) {
 		project, err := gce.service.Projects.Get(gce.projectID).Do()

pkg/cloudprovider/mesos/mesos.go

@@ -78,6 +78,11 @@ func newMesosCloud(configReader io.Reader) (*MesosCloud, error) {
 	}
 }
 
+// Implementation of Instances.CurrentNodeName
+func (c *MesosCloud) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 func (c *MesosCloud) AddSSHKeyToAllInstances(user string, keyData []byte) error {
 	return errors.New("unimplemented")
 }

pkg/cloudprovider/openstack/openstack.go

@@ -317,6 +317,11 @@ func getAddressByName(api *gophercloud.ServiceClient, name string) (string, erro
 	return s, nil
 }
 
+// Implementation of Instances.CurrentNodeName
+func (i *Instances) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 func (i *Instances) AddSSHKeyToAllInstances(user string, keyData []byte) error {
 	return errors.New("unimplemented")
 }

pkg/cloudprovider/ovirt/ovirt.go

@@ -275,6 +275,11 @@ func (v *OVirtCloud) GetNodeResources(name string) (*api.NodeResources, error) {
 	return nil, nil
 }
 
+// Implementation of Instances.CurrentNodeName
+func (v *OVirtCloud) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 func (v *OVirtCloud) AddSSHKeyToAllInstances(user string, keyData []byte) error {
 	return errors.New("unimplemented")
 }

pkg/cloudprovider/rackspace/rackspace.go

@@ -380,6 +380,11 @@ func (i *Instances) AddSSHKeyToAllInstances(user string, keyData []byte) error {
 	return errors.New("unimplemented")
 }
 
+// Implementation of Instances.CurrentNodeName
+func (i *Instances) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 func (i *Instances) GetNodeResources(name string) (*api.NodeResources, error) {
 	glog.V(2).Infof("GetNodeResources(%v) called", name)
 

pkg/cloudprovider/vagrant/vagrant.go

@@ -135,6 +135,11 @@ func (v *VagrantCloud) AddSSHKeyToAllInstances(user string, keyData []byte) erro
 	return errors.New("unimplemented")
 }
 
+// Implementation of Instances.CurrentNodeName
+func (v *VagrantCloud) CurrentNodeName(hostname string) (string, error) {
+	return hostname, nil
+}
+
 // NodeAddresses returns the NodeAddresses of a particular machine instance.
 func (v *VagrantCloud) NodeAddresses(instance string) ([]api.NodeAddress, error) {
 	// Due to vagrant not running with a dedicated DNS setup, we return the IP address of a minion as its hostname at this time

pkg/kubelet/kubelet.go

@@ -1849,6 +1849,7 @@ func (kl *Kubelet) setNodeStatus(node *api.Node) error {
 		}
 		// TODO(roberthbailey): Can we do this without having credentials to talk
 		// to the cloud provider?
+		// TODO(justinsb): We can if CurrentNodeName() was actually CurrentNode() and returned an interface
 		nodeAddresses, err := instances.NodeAddresses(kl.nodeName)
 		if err != nil {
 			return fmt.Errorf("failed to get node address from cloud provider: %v", err)