Do not perform port update in case of baremetal instance.

In case of a baremetal instance, the instance's port binding:host_id
gets updated during instance reboot to the nova compute host id by
the periodic task: _heal_instance_info_cache. This regression was
introduced in commit: I75fd15ac2a29e420c09499f2c41d11259ca811ae

This is an un-desirable change as ironic virt driver did the original
port binding, nova should not update the value.
In case of a baremetal port, the binding:host_id represents the ironic
node_uuid. In case of a SmartNIC(baremetal) port[1] the binding:host_id
represent the SmartNIC hostname and it MUST not change since ironic
relies on that information as well as the Neutron agent that runs on
the SmartNIC.

A new API method was added, "manages_port_bindings()", to ComputeDriver
that defaults to False, and overriden in IronicDriver to True.

A call to this API method is now made in _heal_instance_info_cache() to
prevent port update for instance ports in case the underlying
ComputeDriver manages the port binding.

[1] I658754f7f8c74087b0aabfdef222a2c0b5698541

Change-Id: I47d1aba17cd2e9fff67846cc243c8fbd9ac21659
Closes-Bug: #1822801

nova/compute/manager.py

@@ -7204,8 +7204,14 @@ class ComputeManager(manager.Manager):
         binding_failed or unbound binding:vif_type for any of the instances
         ports.
         """
-        if not utils.is_neutron():
+        # Only update port bindings if compute manager does manage port
+        # bindings instead of the compute driver. For example IronicDriver
+        # manages the port binding for baremetal instance ports, hence,
+        # external intervention with the binding is not desired.
+        if (not utils.is_neutron() or
+                self.driver.manages_network_binding_host_id()):
             return False
+
         search_opts = {'device_id': instance.uuid,
                        'fields': ['binding:host_id', 'binding:vif_type']}
         ports = self.network_api.list_ports(context, **search_opts)

nova/tests/unit/compute/test_compute.py

@@ -7250,6 +7250,19 @@ class ComputeTestCase(BaseTestCase,
             self.assertTrue(val)
             mock_list_ports.assert_called_once_with(ctxt, **search_opts)
 
+    def test_require_nw_info_update_for_baremetal(self):
+        """Tests _require_nw_info_update for baremetal instance,
+        expected behavior is to return False.
+        """
+        compute_mgr = compute_manager.ComputeManager('ironic.IronicDriver')
+        with mock.patch.object(compute_mgr, 'network_api') as \
+                network_api_mock:
+            ctxt = context.get_admin_context()
+            instance = self._create_fake_instance_obj()
+            val = compute_mgr._require_nw_info_update(ctxt, instance)
+            self.assertFalse(val)
+            network_api_mock.assert_not_called()
+
     def _heal_instance_info_cache(self,
                                   _get_instance_nw_info_raise=False,
                                   _get_instance_nw_info_raise_cache=False,

nova/virt/driver.py

@@ -1843,6 +1843,19 @@ class ComputeDriver(object):
         """
         return instance.get('host')
 
+    def manages_network_binding_host_id(self):
+        """Compute driver manages port bindings.
+
+        Used to indicate whether or not the compute driver is responsible
+        for managing port binding details, such as the host_id.
+        By default the ComputeManager will manage port bindings and the
+        host_id associated with a binding using the network API.
+        However, some backends, like Ironic, will manage the port binding
+        host_id out-of-band and the compute service should not override what
+        is set by the backing hypervisor.
+        """
+        return False
+
 
 def load_compute_driver(virtapi, compute_driver=None):
     """Load a compute driver module.

nova/virt/ironic/driver.py

@@ -2176,3 +2176,8 @@ class IronicDriver(virt_driver.ComputeDriver):
         timer.start(interval=CONF.ironic.api_retry_interval).wait()
         LOG.info('Successfully unrescued Ironic node %(node)s',
                  {'node': node_uuid}, instance=instance)
+
+    def manages_network_binding_host_id(self):
+        """IronicDriver manages port bindings for baremetal instances.
+        """
+        return True