Do not hide exception in update_instance_cache_with_nw_info

From time to time an exception is raised in this method causing
the nw_info cache not to be saved. If this occurs we should raise
as this error will cause later errors to occur. For example, one
won't be able to associate a floatingip with the instance as there
is no nw_info found in this table. In addition, the fixed_ips on
the instance won't be returned via the api.

This patch also stubs out update_instance_cache_with_nw_info in a
few tests where an exception was being raised previously but went
unnoticed as it was not reraised but now is.

Related-Bug: #1252849
Related-Bug: #1249065

Change-Id: Ic860f72210ba736e11c10df21c4cb7625e9c0928
(cherry picked from commit 4c03383f21)

nova/network/api.py

@@ -28,6 +28,7 @@ from nova.network import floating_ips
 from nova.network import model as network_model
 from nova.network import rpcapi as network_rpcapi
 from nova.objects import instance_info_cache as info_cache_obj
+from nova.openstack.common import excutils
 from nova.openstack.common.gettextutils import _
 from nova.openstack.common import log as logging
 from nova import policy
@@ -81,7 +82,8 @@ def update_instance_cache_with_nw_info(api, context, instance, nw_info=None,
         ic.network_info = nw_info
         ic.save(update_cells=update_cells)
     except Exception:
-        LOG.exception(_('Failed storing info cache'), instance=instance)
+        with excutils.save_and_reraise_exception():
+            LOG.exception(_('Failed storing info cache'), instance=instance)
 
 
 def wrap_check_policy(func):

nova/tests/api/ec2/test_cloud.py

@@ -304,6 +304,16 @@ class CloudTestCase(test.TestCase):
                                       'floating_ips': []})
         self.stubs.Set(network_api.API, 'get_instance_id_by_floating_address',
                        lambda *args: 1)
+
+        def fake_update_instance_cache_with_nw_info(api, context, instance,
+                                                    nw_info=None,
+                                                    update_cells=True):
+
+            return
+
+        self.stubs.Set(network_api, "update_instance_cache_with_nw_info",
+                       fake_update_instance_cache_with_nw_info)
+
         self.cloud.associate_address(self.context,
                                      instance_id=ec2_id,
                                      public_ip=address)

nova/tests/network/test_api.py

@@ -131,6 +131,14 @@ class ApiTestCase(test.TestCase):
         self.stubs.Set(self.network_api.db, 'instance_info_cache_update',
                        fake_instance_info_cache_update)
 
+        def fake_update_instance_cache_with_nw_info(api, context, instance,
+                                                    nw_info=None,
+                                                    update_cells=True):
+            return
+
+        self.stubs.Set(api, "update_instance_cache_with_nw_info",
+                       fake_update_instance_cache_with_nw_info)
+
         self.network_api.associate_floating_ip(self.context,
                                                new_instance,
                                                '172.24.4.225',