Fix DB access when refreshing the network cache.

When calling ComputeManager.attach_interface(), the following happens:

1) self.network_api.allocate_port_for_instance() is called from within
   ComputeManager.attach_interface();
2) refresh_cache() is called, since it decorates allocate_port_for_instance();
3) refresh_cache calls update_instance_cache_with_nw_info(), with
   "conductor_api=None" since 'conductor_api' cannot be found in the kwargs;
4) update_instance_cache_with_nw_info() calls
   api.db.instance_info_cache_update();
5) Since the call to the database should be made through the conductor, a
   DBNotAllowed exception is raised, which prevents the cache from being updated.

This patch fixes the call to allocate_port_for_instance (step 1) so that
'conductor_api' can be found in the kwargs (step 3).

When using ComputeManager.detach_interface, the exact same problem arises (with
deallocate_port_for_instance instead of allocate_port_for_instance).

This is a first step towards fixing bug #1197192.

Change-Id: I647795907b22790759d3be74afcaf70b712cb338

nova/compute/manager.py

@@ -3542,7 +3542,7 @@ def attach_interface(self, context, instance, network_id, port_id,
         """Use hotplug to add an network adapter to an instance."""
         network_info = self.network_api.allocate_port_for_instance(
             context, instance, port_id, network_id, requested_ip,
-            self.conductor_api)
+            conductor_api=self.conductor_api)
         if len(network_info) != 1:
             LOG.error(_('allocate_port_for_instance returned %(ports)s ports')
                       % dict(ports=len(network_info)))
@@ -3568,8 +3568,7 @@ def detach_interface(self, context, instance, port_id):
                                            "attached") % port_id)
 
         self.network_api.deallocate_port_for_instance(context, instance,
-                                                      port_id,
-                                                      self.conductor_api)
+            port_id, conductor_api=self.conductor_api)
         self.driver.detach_interface(instance, [condemned])
 
     def _get_compute_info(self, context, host):

nova/tests/compute/test_compute.py

@@ -7696,7 +7696,7 @@ def test_attach_interface(self):
         req_ip = '1.2.3.4'
         self.compute.network_api.allocate_port_for_instance(
             self.context, instance, port_id, network_id, req_ip,
-            self.compute.conductor_api).AndReturn(nwinfo)
+            conductor_api=self.compute.conductor_api).AndReturn(nwinfo)
         compute_manager._get_image_meta(self.context, instance['image_ref'])
         self.mox.ReplayAll()
         network, mapping = self.compute.attach_interface(self.context,
@@ -7713,7 +7713,7 @@ def test_detach_interface(self):
                        lambda *a, **k: nwinfo)
         self.stubs.Set(self.compute.network_api,
                        'deallocate_port_for_instance',
-                       lambda a, b, c, d: [])
+                       lambda a, b, c, conductor_api=None: [])
         self.compute.detach_interface(self.context, {}, port_id)
         self.assertEqual(self.compute.driver._interfaces, {})