Move keypair quota error message into exception

The KeypairLimitExceeded exception has a message string which is never
used. We raise this exception and then return a different message to
the API user. For the unified limit work, we want to move to using
oslo.limit's better error messages when available, which means we
need to honor the message in the exception. This just moves the
legacy string into the exception and makes the API use that instead
of overriding it.

Related to bp/unified-limits-nova

Change-Id: I217b3d0551291498191b556f62d78abf159778c2

nova/api/openstack/compute/keypairs.py

@@ -26,7 +26,6 @@ from nova.api.openstack import wsgi
 from nova.api import validation
 from nova.compute import api as compute_api
 from nova import exception
-from nova.i18n import _
 from nova.objects import keypair as keypair_obj
 from nova.policies import keypairs as kp_policies
 
@@ -119,9 +118,8 @@ class KeypairController(wsgi.Controller):
                     context, user_id, name, key_type_value)
                 keypair['private_key'] = private_key
                 return_priv_key = True
-        except exception.KeypairLimitExceeded:
-            msg = _("Quota exceeded, too many key pairs.")
-            raise webob.exc.HTTPForbidden(explanation=msg)
+        except exception.KeypairLimitExceeded as e:
+            raise webob.exc.HTTPForbidden(explanation=str(e))
         except exception.InvalidKeypair as exc:
             raise webob.exc.HTTPBadRequest(explanation=exc.format_message())
         except exception.KeyPairExists as exc:

nova/exception.py

@@ -1270,7 +1270,7 @@ class OnsetFileContentLimitExceeded(OnsetFileLimitExceeded):
 
 
 class KeypairLimitExceeded(OverQuota):
-    msg_fmt = _("Maximum number of key pairs exceeded")
+    msg_fmt = _("Quota exceeded, too many key pairs.")
 
 
 class SecurityGroupLimitExceeded(OverQuota):

nova/tests/unit/compute/test_keypairs.py

@@ -155,7 +155,7 @@ class CreateImportSharedTestMixIn(object):
                        return_value={'user': {
                                          'key_pairs': CONF.quota.key_pairs}})
     def test_quota_limit(self, mock_count_as_dict):
-        msg = "Maximum number of key pairs exceeded"
+        msg = "Quota exceeded, too many key pairs."
         self.assertKeypairRaises(exception.KeypairLimitExceeded, msg, 'foo')