[vmware] VmdkDriverRemoteApi: RPC initialization improvements

Currently, creating the RPC client at the driver initialization
might lead into an issue that, while upgrading to newer releases,
the RPC client will limit the maximum RPC version to the older
release's version, since that version is never refreshed while the
volume backend is running. Initializing the RPC client every time
it's needed will make sure it always refreshes the available
RPC service versions.

Also, inherit the RPC_DEFAULT_VERSION from the VolumeAPI, so that
the smallest available major version is requested by default,
instead of the biggest available version.

Author: leust

cinder/volume/drivers/vmware/remote.py

@@ -28,7 +28,7 @@
 
 class VmdkDriverRemoteApi(rpc.RPCAPI):
     RPC_API_VERSION = VolumeAPI.RPC_API_VERSION
-    RPC_DEFAULT_VERSION = RPC_API_VERSION
+    RPC_DEFAULT_VERSION = VolumeAPI.RPC_DEFAULT_VERSION
     TOPIC = VolumeAPI.TOPIC
     BINARY = VolumeAPI.BINARY
 

cinder/volume/drivers/vmware/vmdk.py

@@ -337,7 +337,6 @@ def __init__(self, *args, **kwargs):
         self.additional_endpoints.extend([
             remote_api.VmdkDriverRemoteService(self)
         ])
-        self._remote_api = remote_api.VmdkDriverRemoteApi()
 
     @staticmethod
     def get_driver_options():
@@ -2645,18 +2644,19 @@ def migrate_volume(self, context, volume, host):
                      {'volume_name': volume.name, 'dest_host': dest_host})
             return (True, None)
 
-        service_locator = self._remote_api.get_service_locator_info(context,
-                                                                    dest_host)
-        ds_info = self._remote_api.select_ds_for_volume(context, dest_host,
-                                                        volume)
+        dest_api = remote_api.VmdkDriverRemoteApi()
+
+        service_locator = dest_api.get_service_locator_info(context, dest_host)
+        ds_info = dest_api.select_ds_for_volume(context, dest_host, volume)
+
         host_ref = vim_util.get_moref(ds_info['host'], 'HostSystem')
         rp_ref = vim_util.get_moref(ds_info['resource_pool'], 'ResourcePool')
         ds_ref = vim_util.get_moref(ds_info['datastore'], 'Datastore')
 
         self.volumeops.relocate_backing(backing, ds_ref, rp_ref, host_ref,
                                         service=service_locator)
         try:
-            self._remote_api.move_volume_backing_to_folder(
+            dest_api.move_volume_backing_to_folder(
                 context, dest_host, volume, ds_info['folder'])
         except Exception:
             # At this point the backing has been migrated to the new host.