Remove 'scheduled_at' - DB cleanup

The 'scheduled_at' field is a part of the Nova instances.
Currently, the 'scheduled_at' field is no longer updated
by the Nova scheduler, instead the 'launched_at' field is
updated for the same purpose. The 'scheduled_at' column is
now redundant and should be removed as a part of DB clean up.

Implements: blueprint cleanup-scheduled-at
Change-Id: I66b55bbd4ad7c381e6a7203c22ac7c2d29e222f6

nova/db/sqlalchemy/api.py

@@ -1581,7 +1581,7 @@ def _handle_objects_related_type_conversions(values):
             values[key] = str(values[key])
 
     datetime_keys = ('created_at', 'deleted_at', 'updated_at',
-                     'launched_at', 'terminated_at', 'scheduled_at')
+                     'launched_at', 'terminated_at')
     convert_objects_related_datetimes(values, *datetime_keys)
 
 

nova/db/sqlalchemy/models.py

@@ -273,7 +273,9 @@ class Instance(BASE, NovaBase):
 
     reservation_id = Column(String(255))
 
-    scheduled_at = Column(DateTime)
+    # NOTE(sbiswas7): 'scheduled_at' is still in the database
+    # and can be removed in the future release.
+
     launched_at = Column(DateTime)
     terminated_at = Column(DateTime)
 

nova/objects/instance.py

@@ -158,6 +158,8 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
 
         'reservation_id': fields.StringField(nullable=True),
 
+        # NOTE(sbiswas7): this field is depcrecated,
+        # will be removed in instance v2.0
         'scheduled_at': fields.DateTimeField(nullable=True),
         'launched_at': fields.DateTimeField(nullable=True),
         'terminated_at': fields.DateTimeField(nullable=True),
@@ -457,6 +459,8 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
                 instance.deleted = db_inst['deleted'] == db_inst['id']
             elif field == 'cleaned':
                 instance.cleaned = db_inst['cleaned'] == 1
+            elif field == 'scheduled_at':
+                instance.scheduled_at = None
             else:
                 instance[field] = db_inst[field]
 
@@ -569,6 +573,9 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
         updates = self.obj_get_changes()
         expected_attrs = [attr for attr in INSTANCE_DEFAULT_FIELDS
                           if attr in updates]
+        if 'scheduled_at' in updates:
+            # NOTE(sbiswas7): 'scheduled_at' is not present in models.
+            del updates['scheduled_at']
         if 'security_groups' in updates:
             updates['security_groups'] = [x.name for x in
                                           updates['security_groups']]
@@ -794,6 +801,10 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
         self._maybe_upgrade_flavor()
         updates = {}
         changes = self.obj_what_changed()
+        if 'scheduled_at' in changes:
+            # NOTE(sbiswas7): Since 'scheduled_at' is removed from models,
+            # we need to discard it.
+            changes.remove('scheduled_at')
 
         for field in self.fields:
             # NOTE(danms): For object fields, we construct and call a
@@ -861,7 +872,6 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
         old_ref, inst_ref = db.instance_update_and_get_original(
                 context, self.uuid, updates,
                 columns_to_join=_expected_cols(expected_attrs))
-
         self._from_db_object(context, self, inst_ref,
                              expected_attrs=expected_attrs)
 

nova/tests/unit/api/openstack/compute/test_consoles.py

@@ -108,7 +108,6 @@ def stub_instance(id, user_id='fake', project_id='fake', host=None,
         "user_data": "",
         "reservation_id": reservation_id,
         "mac_address": "",
-        "scheduled_at": timeutils.utcnow(),
         "launched_at": timeutils.utcnow(),
         "terminated_at": timeutils.utcnow(),
         "availability_zone": "",

nova/tests/unit/api/openstack/fakes.py

@@ -543,7 +543,6 @@ def stub_instance(id=1, user_id=None, project_id=None, host=None,
         "user_data": user_data,
         "reservation_id": reservation_id,
         "mac_address": "",
-        "scheduled_at": timeutils.utcnow(),
         "launched_at": launched_at,
         "terminated_at": terminated_at,
         "availability_zone": availability_zone,

nova/tests/unit/compute/test_resource_tracker.py

@@ -329,7 +329,6 @@ class BaseTestCase(test.TestCase):
             'display_name': None,
             'default_swap_device': None,
             'power_state': None,
-            'scheduled_at': None,
             'access_ip_v6': None,
             'access_ip_v4': None,
             'key_name': None,

nova/tests/unit/db/test_db_api.py

@@ -1938,7 +1938,7 @@ class InstanceTestCase(test.TestCase, ModelsObjectComparatorMixin):
             'access_ip_v6': netaddr.IPAddress('::1'),
             }
         dt_keys = ('created_at', 'deleted_at', 'updated_at',
-                   'launched_at', 'terminated_at', 'scheduled_at')
+                   'launched_at', 'terminated_at')
         dt = timeutils.utcnow()
         dt_utc = dt.replace(tzinfo=iso8601.iso8601.Utc())
         for key in dt_keys:
@@ -1955,7 +1955,7 @@ class InstanceTestCase(test.TestCase, ModelsObjectComparatorMixin):
             'access_ip_v6': netaddr.IPAddress('::1'),
             }
         dt_keys = ('created_at', 'deleted_at', 'updated_at',
-                   'launched_at', 'terminated_at', 'scheduled_at')
+                   'launched_at', 'terminated_at')
         dt = timeutils.utcnow()
         dt_utc = dt.replace(tzinfo=iso8601.iso8601.Utc())
         for key in dt_keys:

nova/tests/unit/db/test_migrations.py

@@ -766,6 +766,22 @@ class NovaMigrationsCheckers(test_migrations.ModelsMigrationsSync,
         # the point-of-view of unit tests, since they use SQLite
         pass
 
+    def filter_metadata_diff(self, diff):
+        # Overriding the parent method to decide on certain attributes
+        # that maybe present in the DB but not in the models.py
+        # Define a whitelist of columns that would be removed from the
+        # DB at a later release.
+        column_whitelist = {'instances': ['scheduled_at']}
+        for element in diff:
+            # Assuming that the diff structure will remain constant
+            # The 4th element in the diff is always the Column object
+            for key, values in column_whitelist.iteritems():
+                table_name = element[3].table.name
+                table_column = element[3].name
+                if key == table_name and table_column in values:
+                    diff.remove(element)
+        return diff
+
 
 class TestNovaMigrationsSQLite(NovaMigrationsCheckers,
                                test_base.DbTestCase,

nova/tests/unit/objects/test_instance.py

@@ -52,7 +52,6 @@ class _TestInstanceObject(object):
                                                  access_ip_v6='::1')
         db_inst['uuid'] = '34fd7606-2ed5-42c7-ad46-76240c088801'
         db_inst['cell_name'] = 'api!child'
-        db_inst['scheduled_at'] = None
         db_inst['terminated_at'] = None
         db_inst['deleted_at'] = None
         db_inst['created_at'] = None
@@ -425,6 +424,17 @@ class _TestInstanceObject(object):
             inst.save()
             self.assertTrue(save_mock.called)
 
+    @mock.patch('nova.db.instance_update_and_get_original')
+    @mock.patch.object(objects.Instance, '_from_db_object')
+    def test_save_skip_scheduled_at(self, mock_fdo, mock_update):
+        mock_update.return_value = None, None
+        inst = instance.Instance(context=self.context, id=123)
+        inst.uuid = 'foo'
+        inst.scheduled_at = None
+        inst.save()
+        self.assertNotIn('scheduled_at',
+                         mock_update.call_args_list[0][0][2])
+
     @mock.patch('nova.db.instance_update_and_get_original')
     @mock.patch.object(objects.Instance, '_from_db_object')
     def test_save_does_not_refresh_pci_devices(self, mock_fdo, mock_update):
@@ -823,6 +833,22 @@ class _TestInstanceObject(object):
         inst.obj_reset_changes()
         self.assertEqual(set(), inst.obj_what_changed())
 
+    def test_create_skip_scheduled_at(self):
+        self.mox.StubOutWithMock(db, 'instance_create')
+        vals = {'host': 'foo-host',
+                'memory_mb': 128,
+                'system_metadata': {'foo': 'bar'},
+                'extra': {}}
+        fake_inst = fake_instance.fake_db_instance(**vals)
+        db.instance_create(self.context, vals).AndReturn(fake_inst)
+        self.mox.ReplayAll()
+        inst = instance.Instance(context=self.context,
+                                 host='foo-host', memory_mb=128,
+                                 scheduled_at=None,
+                                 system_metadata={'foo': 'bar'})
+        inst.create()
+        self.assertEqual(inst.host, 'foo-host')
+
     def test_metadata_change_tracking(self):
         self._test_metadata_change_tracking('metadata')
 
@@ -1412,7 +1438,6 @@ class _TestInstanceListObject(object):
         db_inst = fake_instance.fake_db_instance(id=2,
                                                  access_ip_v4='1.2.3.4',
                                                  access_ip_v6='::1')
-        db_inst['scheduled_at'] = None
         db_inst['terminated_at'] = None
         db_inst['deleted_at'] = None
         db_inst['created_at'] = None