Merge pull request kubernetes#50858 from andrewsykim/49308

Automatic merge from submit-queue (batch tested with PRs 51148, 50816, 49741, 50858, 51223)

cloudprovider.Zones should support external cloud providers

**What this PR does / why we need it**:
Provides methods in cloudprovider.Zones that allows external cloud providers to set the correct zone labels to nodes. Part of kubernetes#48690

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: 
fixes kubernetes#49308

**Special notes for your reviewer**:
Should help with getting ccm/external cloud providers to beta. 

**Release note**:
```release-note
cloudprovider.Zones should support external cloud providers
```

cc @luxas @wlan0 @thockin

pkg/cloudprovider/providers/openstack/openstack.go

@@ -549,6 +549,20 @@ func (os *OpenStack) GetZone() (cloudprovider.Zone, error) {
 	return zone, nil
 }
 
+// GetZoneByProviderID implements Zones.GetZoneByProviderID
+// This is particularly useful in external cloud providers where the kubelet
+// does not initialize node data.
+func (os *OpenStack) GetZoneByProviderID(providerID string) (cloudprovider.Zone, error) {
+	return cloudprovider.Zone{}, errors.New("GetZoneByProviderID not implemented")
+}
+
+// GetZoneByNodeName implements Zones.GetZoneByNodeName
+// This is particularly useful in external cloud providers where the kubelet
+// does not initialize node data.
+func (os *OpenStack) GetZoneByNodeName(nodeName types.NodeName) (cloudprovider.Zone, error) {
+	return cloudprovider.Zone{}, errors.New("GetZoneByNodeName not imeplemented")
+}
+
 func (os *OpenStack) Routes() (cloudprovider.Routes, bool) {
 	glog.V(4).Info("openstack.Routes() called")