Allow block_migration and disk_over_commit to be None

Bump compute rpc api to 4.11 to allow block_migration and
disk_over_commit to be None for check_can_live_migrate_destination.

If compute rcp client get request with vesion lower than 4.10 and
one of block_migration or disk_over_commit is None value, raise an
exception LiveMigrationWithOldNovaNotSupported.

Partially implements: blueprint making-live-migration-api-friendly
Change-Id: I43119bfd2769888b2802ab0a51ba7becedaf569d

nova/compute/manager.py

@@ -673,7 +673,7 @@ class ComputeVirtAPI(virtapi.VirtAPI):
 class ComputeManager(manager.Manager):
     """Manages the running instances from creation to destruction."""
 
-    target = messaging.Target(version='4.10')
+    target = messaging.Target(version='4.11')
 
     # How long to wait in seconds before re-issuing a shutdown
     # signal to an instance during power off.  The overall
@@ -5050,7 +5050,9 @@ class ComputeManager(manager.Manager):
         :param context: security context
         :param instance: dict of instance data
         :param block_migration: if true, prepare for block migration
+                                if None, calculate it in driver
         :param disk_over_commit: if true, allow disk over commit
+                                 if None, ignore disk usage checking
         :returns: a dict containing migration info
         """
         return self._do_check_can_live_migrate_destination(ctxt, instance,

nova/compute/rpcapi.py

@@ -327,6 +327,7 @@ class ComputeAPI(object):
         * ...  - Remove refresh_provider_fw_rules()
         * 4.9  - Add live_migration_force_complete()
         * 4.10  - Add live_migration_abort()
+        * 4.11 - Allow block_migration and disk_over_commit be None
     '''
 
     VERSION_ALIASES = {
@@ -435,7 +436,18 @@ class ComputeAPI(object):
 
     def check_can_live_migrate_destination(self, ctxt, instance, destination,
                                            block_migration, disk_over_commit):
-        version = '4.0'
+        version = '4.11'
+        if not self.client.can_send_version(version):
+            # NOTE(eliqiao): This is a new feature that is only available
+            # once all compute nodes support at least version 4.11.
+            # This means the new REST API that supports this needs to handle
+            # this exception correctly. This can all be removed when we bump
+            # the major version of this RPC API.
+            if block_migration is None or disk_over_commit is None:
+                raise exception.LiveMigrationWithOldNovaNotSupported()
+            else:
+                version = '4.0'
+
         cctxt = self.client.prepare(server=destination, version=version)
         result = cctxt.call(ctxt, 'check_can_live_migrate_destination',
                             instance=instance,

nova/exception.py

@@ -1857,6 +1857,11 @@ class LiveMigrationWithOldNovaNotSafe(NovaException):
                 "Upgrade Nova on %(server)s and try again.")
 
 
+class LiveMigrationWithOldNovaNotSupported(NovaException):
+    msg_fmt = _("Live migration with API v2.25 requires all the Mitaka "
+                "upgrade to be complete before it is available.")
+
+
 class LiveMigrationURINotAvailable(NovaException):
     msg_fmt = _('No live migration URI configured and no default available '
                 'for "%(virt_type)s" hypervisor virtualization type.')

nova/objects/service.py

@@ -29,7 +29,7 @@ LOG = logging.getLogger(__name__)
 
 
 # NOTE(danms): This is the global service version counter
-SERVICE_VERSION = 8
+SERVICE_VERSION = 9
 
 
 # NOTE(danms): This is our SERVICE_VERSION history. The idea is that any
@@ -69,6 +69,8 @@ SERVICE_VERSION_HISTORY = (
     {'compute_rpc': '4.9'},
     # Version 8: Add live_migration_abort in the compute_rpc
     {'compute_rpc': '4.10'},
+    # Version 9: Allow block_migration and disk_over_commit be None
+    {'compute_rpc': '4.11'},
 )
 
 

nova/tests/unit/compute/test_rpcapi.py

@@ -666,3 +666,13 @@ class ComputeRpcAPITestCase(test.NoDBTestCase):
                                          'migrate_data': {}},
                                callret=None,
                                calltype='cast')
+
+    def test_check_can_live_migrate_destination_old_compute(self):
+        self.flags(compute='4.10', group='upgrade_levels')
+        self.assertRaises(exception.LiveMigrationWithOldNovaNotSupported,
+                          self._test_compute_api,
+                          'check_can_live_migrate_destination', 'call',
+                          instance=self.fake_instance_obj,
+                          block_migration=None,
+                          destination='dest',
+                          disk_over_commit=None, version='4.11')