Add requested_destination field to RequestSpec

As agreed in the spec, we want to provide to the scheduler the possible
destination asked by the admin when calling evacuate or live-migrate.
Adding a possibility to default the field to None if an old RequestSpec
or a legacy dict wants to hydrate.

Change-Id: I6ddcaaca37fc5387c2d2e9f51c67ea9e85acb5c5
Partially-Implements: blueprint check-destination-on-migrations-newton

nova/objects/request_spec.py

@@ -13,6 +13,7 @@
 #    under the License.
 
 from oslo_serialization import jsonutils
+from oslo_utils import versionutils
 import six
 
 from nova.db.sqlalchemy import api as db
@@ -25,6 +26,8 @@ from nova.objects import instance as obj_instance
 from nova.scheduler import utils as scheduler_utils
 from nova.virt import hardware
 
+REQUEST_SPEC_OPTIONAL_ATTRS = ['requested_destination']
+
 
 @base.NovaObjectRegistry.register
 class RequestSpec(base.NovaObject):
@@ -34,7 +37,8 @@ class RequestSpec(base.NovaObject):
     # Version 1.3: InstanceGroup version 1.10
     # Version 1.4: ImageMeta version 1.7
     # Version 1.5: Added get_by_instance_uuid(), create(), save()
-    VERSION = '1.5'
+    # Version 1.6: Added requested_destination
+    VERSION = '1.6'
 
     fields = {
         'id': fields.IntegerField(),
@@ -50,6 +54,9 @@ class RequestSpec(base.NovaObject):
         'ignore_hosts': fields.ListOfStringsField(nullable=True),
         'force_hosts': fields.ListOfStringsField(nullable=True),
         'force_nodes': fields.ListOfStringsField(nullable=True),
+        'requested_destination': fields.ObjectField('Destination',
+                                                    nullable=True,
+                                                    default=None),
         'retry': fields.ObjectField('SchedulerRetries', nullable=True),
         'limits': fields.ObjectField('SchedulerLimits', nullable=True),
         'instance_group': fields.ObjectField('InstanceGroup', nullable=True),
@@ -60,6 +67,24 @@ class RequestSpec(base.NovaObject):
         'instance_uuid': fields.UUIDField(),
     }
 
+    def obj_make_compatible(self, primitive, target_version):
+        super(RequestSpec, self).obj_make_compatible(primitive, target_version)
+        target_version = versionutils.convert_version_to_tuple(target_version)
+        if target_version < (1, 6):
+            if 'requested_destination' in primitive:
+                del primitive['requested_destination']
+
+    def obj_load_attr(self, attrname):
+        if attrname not in REQUEST_SPEC_OPTIONAL_ATTRS:
+            raise exception.ObjectActionError(
+                action='obj_load_attr',
+                reason='attribute %s not lazy-loadable' % attrname)
+
+        # NOTE(sbauza): In case the primitive was not providing that field
+        # because of a previous RequestSpec version, we want to default
+        # that field in order to have the same behaviour.
+        self.obj_set_defaults(attrname)
+
     @property
     def vcpus(self):
         return self.flavor.vcpus
@@ -222,6 +247,11 @@ class RequestSpec(base.NovaObject):
         spec._populate_group_info(filter_properties)
         scheduler_hints = filter_properties.get('scheduler_hints', {})
         spec._from_hints(scheduler_hints)
+
+        # NOTE(sbauza): Default the other fields that are not part of the
+        # original contract
+        spec.obj_set_defaults()
+
         return spec
 
     def get_scheduler_hint(self, hint_name, default=None):
@@ -365,6 +395,10 @@ class RequestSpec(base.NovaObject):
         spec_obj._from_limits(filter_properties.get('limits', {}))
         spec_obj._from_hints(filter_properties.get('scheduler_hints', {}))
         spec_obj.availability_zone = availability_zone
+
+        # NOTE(sbauza): Default the other fields that are not part of the
+        # original contract
+        spec_obj.obj_set_defaults()
         return spec_obj
 
     @staticmethod
@@ -548,6 +582,20 @@ def migrate_instances_add_request_spec(context, max_count):
     return count_all, count_hit
 
 
+@base.NovaObjectRegistry.register
+class Destination(base.NovaObject):
+    # Version 1.0: Initial version
+    VERSION = '1.0'
+
+    fields = {
+        'host': fields.StringField(),
+        # NOTE(sbauza): Given we want to split the host/node relationship later
+        # and also remove the possibility to have multiple nodes per service,
+        # let's provide a possible nullable node here.
+        'node': fields.StringField(nullable=True),
+    }
+
+
 @base.NovaObjectRegistry.register
 class SchedulerRetries(base.NovaObject):
     # Version 1.0: Initial version

nova/tests/unit/fake_request_spec.py

@@ -85,6 +85,7 @@ def fake_spec_obj(remove_id=False):
     req_obj.force_hosts = ['host1', 'host3']
     req_obj.force_nodes = ['node1', 'node2']
     req_obj.scheduler_hints = {'hint': ['over-there']}
+    req_obj.requested_destination = None
     # This should never be a changed field
     req_obj.obj_reset_changes(['id'])
     return req_obj

nova/tests/unit/objects/test_objects.py

@@ -1112,6 +1112,7 @@ object_data = {
     'ComputeNodeList': '1.14-3b6f4f5ade621c40e70cb116db237844',
     'DNSDomain': '1.0-7b0b2dab778454b6a7b6c66afe163a1a',
     'DNSDomainList': '1.0-4ee0d9efdfd681fed822da88376e04d2',
+    'Destination': '1.0-4c59dd1288b2e7adbda6051a2de59183',
     'DeviceMetadata': '1.0-04eb8fd218a49cbc3b1e54b774d179f7',
     'DeviceMetadataList': '1.0-15ecf022a68ddbb8c2a6739cfc9f8f5e',
     'DiskMetadata': '1.0-e7a0f1ccccf10d26a76b28e7492f3788',
@@ -1178,7 +1179,7 @@ object_data = {
     'PciDevicePoolList': '1.1-15ecf022a68ddbb8c2a6739cfc9f8f5e',
     'Quotas': '1.2-1fe4cd50593aaf5d36a6dc5ab3f98fb3',
     'QuotasNoOp': '1.2-e041ddeb7dc8188ca71706f78aad41c1',
-    'RequestSpec': '1.5-576a249869c161e17b7cd6d55f9d85f3',
+    'RequestSpec': '1.6-c1cb516acdf120d367a42d343ed695b5',
     'ResourceProvider': '1.0-57a9a344b0faed9cf6d6811835b6deb6',
     'S3ImageMapping': '1.0-7dd7366a890d82660ed121de9092276e',
     'SchedulerLimits': '1.0-249c4bd8e62a9b327b7026b7f19cc641',

nova/tests/unit/objects/test_request_spec.py

@@ -15,6 +15,7 @@
 import mock
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
+from oslo_versionedobjects import base as ovo_base
 
 from nova import context
 from nova import exception
@@ -546,6 +547,17 @@ class _TestRequestSpecObject(object):
         self.assertIsNone(req_obj.force_nodes)
         mock_reset.assert_called_once_with(['force_hosts', 'force_nodes'])
 
+    def test_compat_requested_destination(self):
+        req_obj = objects.RequestSpec()
+        versions = ovo_base.obj_tree_get_versions('RequestSpec')
+        primitive = req_obj.obj_to_primitive(target_version='1.5',
+                                             version_manifest=versions)
+        self.assertNotIn('requested_destination', primitive)
+
+    def test_default_requested_destination(self):
+        req_obj = objects.RequestSpec()
+        self.assertIsNone(req_obj.requested_destination)
+
 
 class TestRequestSpecObject(test_objects._LocalTest,
                             _TestRequestSpecObject):