Keep updating allocations for Ironic

When ironic updates the instance.flavor to require the new custom
resource class, we really need the allocations to get updated. Easiest
way to do that is to make the resource tracker keep updating allocations
for the ironic virt driver. This can be dropped once the transition to
custom resource classes is complete.

If we were not to claim the extra resources, placement will pick nodes
that already have instances running on them when you boot an instance
with a flavor that only requests the custom resource class. This should
be what all ironic flavors do, before the upgrade to queens is
performed.

Closes-Bug: #1724589

Change-Id: Ibbf65a8d817d359786abcdffa6358089ed1107f6
(cherry picked from commit 5c2b867)

nova/compute/resource_tracker.py

@@ -1010,7 +1010,7 @@ def _update_usage_from_migrations(self, context, migrations, nodename):
                 continue
 
     def _update_usage_from_instance(self, context, instance, nodename,
-            is_removed=False, has_ocata_computes=False):
+            is_removed=False, require_allocation_refresh=False):
         """Update usage for a single instance."""
 
         uuid = instance['uuid']
@@ -1038,10 +1038,9 @@ def _update_usage_from_instance(self, context, instance, nodename,
                 self.pci_tracker.update_pci_for_instance(context,
                                                          instance,
                                                          sign=sign)
-            if has_ocata_computes:
-                LOG.debug("We're on a Pike compute host in a deployment "
-                          "with Ocata compute hosts. Auto-correcting "
-                          "allocations to handle Ocata-style assumptions.")
+            if require_allocation_refresh:
+                LOG.debug("Auto-correcting allocations to handle Ocata "
+                          "assumptions.")
                 self.reportclient.update_instance_allocation(cn, instance,
                                                              sign)
             else:
@@ -1135,10 +1134,16 @@ def _update_usage_from_instances(self, context, instances, nodename):
             context, 'nova-compute')
         has_ocata_computes = compute_version < 22
 
+        # Some drivers (ironic) still need the allocations to be
+        # fixed up, as they transition the way their inventory is reported.
+        require_allocation_refresh = (
+            has_ocata_computes or
+            self.driver.requires_allocation_refresh)
+
         for instance in instances:
             if instance.vm_state not in vm_states.ALLOW_RESOURCE_REMOVAL:
                 self._update_usage_from_instance(context, instance, nodename,
-                    has_ocata_computes=has_ocata_computes)
+                    require_allocation_refresh=require_allocation_refresh)
 
         self._remove_deleted_instances_allocations(context, cn)
 

nova/tests/unit/compute/test_resource_tracker.py

@@ -2571,6 +2571,40 @@ def test(version_mock, uufi, rdia):
         self.assertEqual(-1024, cn.free_ram_mb)
         self.assertEqual(-1, cn.free_disk_gb)
 
+    def test_update_usage_from_instances_refreshes_ironic(self):
+        self.rt.driver.requires_allocation_refresh = True
+
+        @mock.patch.object(self.rt,
+                           '_remove_deleted_instances_allocations')
+        @mock.patch.object(self.rt, '_update_usage_from_instance')
+        @mock.patch('nova.objects.Service.get_minimum_version',
+                    return_value=22)
+        def test(version_mock, uufi, rdia):
+            self.rt._update_usage_from_instances('ctxt', [self.instance],
+                                                 _NODENAME)
+
+            uufi.assert_called_once_with('ctxt', self.instance, _NODENAME,
+                                         require_allocation_refresh=True)
+
+        test()
+
+    def test_update_usage_from_instances_no_refresh(self):
+        self.rt.driver.requires_allocation_refresh = False
+
+        @mock.patch.object(self.rt,
+                           '_remove_deleted_instances_allocations')
+        @mock.patch.object(self.rt, '_update_usage_from_instance')
+        @mock.patch('nova.objects.Service.get_minimum_version',
+                    return_value=22)
+        def test(version_mock, uufi, rdia):
+            self.rt._update_usage_from_instances('ctxt', [self.instance],
+                                                 _NODENAME)
+
+            uufi.assert_called_once_with('ctxt', self.instance, _NODENAME,
+                                         require_allocation_refresh=False)
+
+        test()
+
     @mock.patch('nova.scheduler.utils.resources_from_flavor')
     def test_delete_allocation_for_evacuated_instance(
             self, mock_resource_from_flavor):

nova/tests/unit/virt/ironic/test_driver.py

@@ -134,6 +134,8 @@ def test_driver_capabilities(self):
                              'supports_migrate_to_same_host'],
                          'Driver capabilities for '
                          '\'supports_migrate_to_same_host\' is invalid')
+        self.assertTrue(self.driver.requires_allocation_refresh,
+                        'Driver requires allocation refresh')
 
     def test__get_hypervisor_type(self):
         self.assertEqual('ironic', self.driver._get_hypervisor_type())

nova/tests/unit/virt/libvirt/test_driver.py

@@ -804,6 +804,8 @@ def test_driver_capabilities(self):
                         'Driver capabilities for '
                         '\'supports_extend_volume\' '
                         'is invalid')
+        self.assertFalse(drvr.requires_allocation_refresh,
+                         'Driver does not need allocation refresh')
 
     def create_fake_libvirt_mock(self, **kwargs):
         """Defining mocks for LibvirtDriver(libvirt is not used)."""

nova/virt/driver.py

@@ -132,6 +132,8 @@ class ComputeDriver(object):
         "supports_extend_volume": False,
     }
 
+    requires_allocation_refresh = False
+
     def __init__(self, virtapi):
         self.virtapi = virtapi
         self._compute_event_callback = None

nova/virt/ironic/driver.py

@@ -135,6 +135,12 @@ class IronicDriver(virt_driver.ComputeDriver):
                     "supports_attach_interface": True
                     }
 
+    # Needed for exiting instances to have allocations for custom resource
+    # class resources
+    # TODO(johngarbutt) we should remove this once the resource class
+    # migration has been completed.
+    requires_allocation_refresh = True
+
     def __init__(self, virtapi, read_only=False):
         super(IronicDriver, self).__init__(virtapi)
         global ironic