Clarify TooManyInstances exception message.

Fixes LP 1031737.

Previously the message indicated the number of instances requested
and an incorrect indication of the headroom, in the case where ram
or cores was the resource gone over-quota (as opposed to the number
of raw instances).

Change-Id: I9f7f3203f0e644ba533940a87e496bfd09da0460

nova/compute/api.py

@@ -194,8 +194,8 @@ def _check_num_instances_quota(self, context, instance_type, min_count,
                              (usages[res]['in_use'] + usages[res]['reserved']))
                             for res in quotas.keys())
 
-            # Reduce 'allowed' to the minimum supported
             allowed = headroom['instances']
+            # Reduce 'allowed' instances in line with the cores & ram headroom
             if instance_type['vcpus']:
                 allowed = min(allowed,
                               headroom['cores'] // instance_type['vcpus'])
@@ -204,7 +204,6 @@ def _check_num_instances_quota(self, context, instance_type, min_count,
                               headroom['ram'] // instance_type['memory_mb'])
 
             # Convert to the appropriate exception message
-            pid = context.project_id
             if allowed <= 0:
                 msg = _("Cannot run any more instances of this type.")
                 allowed = 0
@@ -216,14 +215,19 @@ def _check_num_instances_quota(self, context, instance_type, min_count,
                 msg = (_("Can only run %s more instances of this type.") %
                        allowed)
 
-            used = quotas['instances'] - headroom['instances']
-            total_allowed = used + allowed
+            resource = overs[0]
+            used = quotas[resource] - headroom[resource]
+            total_allowed = used + headroom[resource]
             overs = ','.join(overs)
 
+            pid = context.project_id
             LOG.warn(_("%(overs)s quota exceeded for %(pid)s,"
                   " tried to run %(min_count)s instances. %(msg)s"), locals())
-            raise exception.TooManyInstances(overs=overs, req=min_count,
-                                             used=used, allowed=total_allowed)
+            requested = dict(instances=min_count, cores=req_cores, ram=req_ram)
+            raise exception.TooManyInstances(overs=overs,
+                                             req=requested[resource],
+                                             used=used, allowed=total_allowed,
+                                             resource=resource)
 
         return max_count, reservations
 

nova/exception.py

@@ -1007,7 +1007,7 @@ class QuotaError(NovaException):
 
 class TooManyInstances(QuotaError):
     message = _("Quota exceeded for %(overs)s: Requested %(req)s,"
-                " but already used %(used)d of %(allowed)d instances")
+                " but already used %(used)d of %(allowed)d %(resource)s")
 
 
 class VolumeSizeTooLarge(QuotaError):

nova/tests/api/openstack/compute/test_servers.py

@@ -1344,7 +1344,7 @@ def return_servers_with_host(context, *args, **kwargs):
             self.assertEqual(s['name'], 'server%d' % (i + 1))
 
     def test_delete_server_instance(self):
-        fakes.stub_out_instance_quota(self.stubs, 0)
+        fakes.stub_out_instance_quota(self.stubs, 0, 10)
         req = fakes.HTTPRequest.blank('/v2/fake/servers/%s' % FAKE_UUID)
         req.method = 'DELETE'
 
@@ -1362,7 +1362,7 @@ def instance_destroy_mock(*args, **kwargs):
         self.assertEqual(self.server_delete_called, True)
 
     def test_delete_server_instance_while_building(self):
-        fakes.stub_out_instance_quota(self.stubs, 0)
+        fakes.stub_out_instance_quota(self.stubs, 0, 10)
         req = fakes.HTTPRequest.blank('/v2/fake/servers/%s' % FAKE_UUID)
         req.method = 'DELETE'
 
@@ -2393,11 +2393,12 @@ def test_create_location(self):
 
         self.assertEqual(robj['Location'], selfhref)
 
-    def test_create_instance_above_quota(self):
-        fakes.stub_out_instance_quota(self.stubs, 0)
+    def _do_test_create_instance_above_quota(self, resource, allowed, quota,
+                                             expected_msg):
+        fakes.stub_out_instance_quota(self.stubs, allowed, quota, resource)
         image_uuid = 'c905cedb-7281-47e4-8a62-f26bc5fc4c77'
         body = dict(server=dict(
-            name='server_test', imageRef=image_uuid, flavorRef=2,
+            name='server_test', imageRef=image_uuid, flavorRef=3,
             metadata={'hello': 'world', 'open': 'stack'},
             personality={}))
         req = fakes.HTTPRequest.blank('/v2/fake/servers')
@@ -2408,9 +2409,22 @@ def test_create_instance_above_quota(self):
             server = self.controller.create(req, body).obj['server']
             self.fail('expected quota to be exceeded')
         except webob.exc.HTTPRequestEntityTooLarge as e:
-            self.assertEquals(e.explanation,
-                      _('Quota exceeded for instances: Requested 1, but'
-                        ' already used 0 of 0 instances'))
+            self.assertEquals(e.explanation, expected_msg)
+
+    def test_create_instance_above_quota_instances(self):
+        msg = _('Quota exceeded for instances: Requested 1, but'
+                ' already used 10 of 10 instances')
+        self._do_test_create_instance_above_quota('instances', 0, 10, msg)
+
+    def test_create_instance_above_quota_ram(self):
+        msg = _('Quota exceeded for ram: Requested 4096, but'
+                ' already used 8192 of 10240 ram')
+        self._do_test_create_instance_above_quota('ram', 2048, 10 * 1024, msg)
+
+    def test_create_instance_above_quota_cores(self):
+        msg = _('Quota exceeded for cores: Requested 2, but'
+                ' already used 9 of 10 cores')
+        self._do_test_create_instance_above_quota('cores', 1, 10, msg)
 
 
 class TestServerCreateRequestXMLDeserializer(test.TestCase):

nova/tests/api/openstack/fakes.py

@@ -129,19 +129,20 @@ def fake_rate_init(self, app):
         '__call__', fake_wsgi)
 
 
-def stub_out_instance_quota(stubs, allowed):
+def stub_out_instance_quota(stubs, allowed, quota, resource='instances'):
     def fake_reserve(context, **deltas):
-        instances = deltas.pop('instances', 0)
-        if instances > allowed:
-            raise exc.OverQuota(overs=['instances'], quotas=dict(
-                    instances=allowed,
-                    cores=10000,
-                    ram=10000 * 1024,
-                    ), usages=dict(
-                    instances=dict(in_use=0, reserved=0),
-                    cores=dict(in_use=0, reserved=0),
-                    ram=dict(in_use=0, reserved=0),
-                    ))
+        requested = deltas.pop(resource, 0)
+        if requested > allowed:
+            quotas = dict(instances=1, cores=1, ram=1)
+            quotas[resource] = quota
+            usages = dict(instances=dict(in_use=0, reserved=0),
+                          cores=dict(in_use=0, reserved=0),
+                          ram=dict(in_use=0, reserved=0))
+            usages[resource]['in_use'] = (quotas[resource] * 0.9 -
+                                          allowed)
+            usages[resource]['reserved'] = quotas[resource] * 0.1
+            raise exc.OverQuota(overs=[resource], quotas=quotas,
+                                usages=usages)
     stubs.Set(QUOTAS, 'reserve', fake_reserve)