Add Destination.allow_cross_cell_move field

This adds a new boolean field, allow_cross_cell_move, to
the Destination object used within a RequestSpec.

This will be used during a cross-cell resize when asking
the scheduler for a target host whether or not that host
should be restricted to the current cell or if the host
can come from another cell. Furthermore, it will be used
in a scheduler weigher which will prefer candidate target
hosts in the current cell rather than a different cell.

Part of blueprint cross-cell-resize

Change-Id: I6e226321348f5d64d16b0bae26ad31c52debf0bc

Author: mriedem

nova/objects/request_spec.py

@@ -878,7 +878,8 @@ class Destination(base.NovaObject):
     # Version 1.0: Initial version
     # Version 1.1: Add cell field
     # Version 1.2: Add aggregates field
-    VERSION = '1.2'
+    # Version 1.3: Add allow_cross_cell_move field.
+    VERSION = '1.3'
 
     fields = {
         'host': fields.StringField(),
@@ -892,11 +893,17 @@ class Destination(base.NovaObject):
         # are passed to placement.  See require_aggregates() below.
         'aggregates': fields.ListOfStringsField(nullable=True,
                                                 default=None),
+        # NOTE(mriedem): allow_cross_cell_move defaults to False so that the
+        # scheduler by default selects hosts from the cell specified in the
+        # cell field.
+        'allow_cross_cell_move': fields.BooleanField(default=False),
     }
 
     def obj_make_compatible(self, primitive, target_version):
         super(Destination, self).obj_make_compatible(primitive, target_version)
         target_version = versionutils.convert_version_to_tuple(target_version)
+        if target_version < (1, 3) and 'allow_cross_cell_move' in primitive:
+            del primitive['allow_cross_cell_move']
         if target_version < (1, 2):
             if 'aggregates' in primitive:
                 del primitive['aggregates']

nova/tests/unit/objects/test_objects.py

@@ -1049,7 +1049,7 @@ def obj_name(cls):
     'CpuDiagnostics': '1.0-d256f2e442d1b837735fd17dfe8e3d47',
     'DNSDomain': '1.0-7b0b2dab778454b6a7b6c66afe163a1a',
     'DNSDomainList': '1.0-4ee0d9efdfd681fed822da88376e04d2',
-    'Destination': '1.2-74854e8cfe7fe616294d93a5d189d885',
+    'Destination': '1.3-07240d223a95c8b9399f7af21091ccfd',
     'DeviceBus': '1.0-77509ea1ea0dd750d5864b9bd87d3f9d',
     'DeviceMetadata': '1.0-04eb8fd218a49cbc3b1e54b774d179f7',
     'Diagnostics': '1.0-38ad3e9b1a59306253fc03f97936db95',

nova/tests/unit/objects/test_request_spec.py

@@ -325,6 +325,7 @@ def test_from_primitives_with_requested_destination(self):
     def test_from_components(self):
         ctxt = context.RequestContext('fake-user', 'fake-project')
         destination = objects.Destination(host='foo')
+        self.assertFalse(destination.allow_cross_cell_move)
         instance = fake_instance.fake_instance_obj(ctxt)
         image = {'id': uuids.image_id, 'properties': {'mappings': []},
                  'status': 'fake-status', 'location': 'far-away'}
@@ -344,6 +345,7 @@ def test_from_components(self):
         # just making sure that the context is set by the method
         self.assertEqual(ctxt, spec._context)
         self.assertEqual(destination, spec.requested_destination)
+        self.assertFalse(spec.requested_destination.allow_cross_cell_move)
 
     @mock.patch('nova.objects.RequestSpec._populate_group_info')
     def test_from_components_with_instance_group(self, mock_pgi):
@@ -896,10 +898,18 @@ def test_destination_require_aggregates(self):
         destination.require_aggregates(['baz'])
         self.assertEqual(['foo,bar', 'baz'], destination.aggregates)
 
-    def test_destination_1dotoh(self):
-        destination = objects.Destination(aggregates=['foo'])
-        primitive = destination.obj_to_primitive(target_version='1.0')
-        self.assertNotIn('aggregates', primitive['nova_object.data'])
+    def test_destination_obj_make_compatible(self):
+        destination = objects.Destination(
+            aggregates=['foo'], host='fake-host', allow_cross_cell_move=False)
+        primitive = destination.obj_to_primitive(
+            target_version='1.2')['nova_object.data']
+        self.assertIn('aggregates', primitive)
+        self.assertNotIn('allow_cross_cell_move', primitive)
+
+        primitive = destination.obj_to_primitive(
+            target_version='1.0')['nova_object.data']
+        self.assertNotIn('aggregates', primitive)
+        self.assertEqual('fake-host', primitive['host'])
 
     def test_create_raises_on_unchanged_object(self):
         ctxt = context.RequestContext(uuids.user_id, uuids.project_id)