Call get_instance_nw_info with elevated context, as documented in nov…

…a/network/manager.py

* Fixes Bug 904976
* Add coverage for this in associate_floating_ip unit test

Change-Id: I5bc35632ca382d011eb42e738140ba54d9cdc93f

nova/compute/api.py

@@ -1555,7 +1555,7 @@ def associate_floating_ip(self, context, instance, address):
         # accommodate the info containing floating as well as fixed ip
         # addresses
         fixed_ip_addrs = []
-        for info in self.network_api.get_instance_nw_info(context,
+        for info in self.network_api.get_instance_nw_info(context.elevated(),
                                                           instance):
             ips = info[1]['ips']
             fixed_ip_addrs.extend([ip_dict['ip'] for ip_dict in ips])

nova/tests/test_compute.py

@@ -1868,7 +1868,8 @@ def fake_associate_ip_network_api(self, ctxt, floating_address,
 
         nw_info = fake_network.fake_get_instance_nw_info(self.stubs, 1)
 
-        def fake_get_nw_info(self, ctxt, instance):
+        def fake_get_nw_info(cls, ctxt, instance):
+            self.assertTrue(ctxt.is_admin)
             return nw_info
 
         self.stubs.Set(nova.network.API, 'associate_floating_ip',