Support -1 as unlimited quota restraint in Trove.

In other projects like nova and neutron, hard limit -1 often means
unlimited quota restraint. But Trove dose not support that. This patch
aims at two things:
1. Support -1, as unlimited quota restraint in check_quotas()
2. Add quota check to accept only -1, not -2 or other negative numbers
when updating quotas.

Change-Id: I028e6d7814ff240aa3f697e3d6ac8c7bac5bf3fd
Closes-bug: #1729791
Signed-off-by: Fan Zhang <zh.f@outlook.com>

trove/common/exception.py

@@ -206,6 +206,12 @@ class OverLimit(TroveError):
                          "rate.")
 
 
+class QuotaLimitTooSmall(TroveError):
+
+    message = _("Quota limit '%(limit)s' for '%(resource)s' is too small"
+                " - must be at least '-1'.")
+
+
 class QuotaExceeded(TroveError):
 
     message = _("Quota exceeded for resources: %(overs)s.")

trove/extensions/mgmt/quota/service.py

@@ -55,6 +55,9 @@ class QuotaController(wsgi.Controller):
         for resource, limit in body['quotas'].items():
             if limit is None:
                 continue
+            elif limit < -1:
+                raise exception.QuotaLimitTooSmall(limit=limit,
+                                                   resource=resource)
             if resource == "xmlns":
                 continue
             if resource not in registered_resources:

trove/quota/quota.py

@@ -147,6 +147,7 @@ class DbQuotaDriver(object):
 
         overs = [resource for resource in deltas
                  if (int(deltas[resource]) > 0 and
+                     quotas[resource].hard_limit >= 0 and
                      (quota_usages[resource].in_use +
                       quota_usages[resource].reserved +
                       int(deltas[resource])) > quotas[resource].hard_limit)]

trove/tests/unittests/quota/test_quota.py

@@ -144,6 +144,15 @@ class QuotaControllerTest(trove_testtools.TestCase):
             self.assertEqual(200, result.status)
             self.assertEqual(10, result._data['quotas']['volumes'])
 
+    def test_update_resource_with_invalid_negative_number(self):
+        quota = MagicMock(spec=Quota)
+        with patch.object(DatabaseModelBase, 'find_by', return_value=quota):
+            body = {'quotas': {'instances': -2}}
+            self.assertRaises(exception.QuotaLimitTooSmall,
+                              self.controller.update,
+                              self.req, body, FAKE_TENANT1,
+                              FAKE_TENANT2)
+
 
 class DbQuotaDriverTest(trove_testtools.TestCase):
 
@@ -386,6 +395,34 @@ class DbQuotaDriverTest(trove_testtools.TestCase):
         self.assertEqual(0, usages[Resource.VOLUMES].in_use)
         self.assertEqual(0, usages[Resource.VOLUMES].reserved)
 
+    def test_check_quota_with_unlimited_quota(self):
+
+        FAKE_QUOTA_USAGE = [QuotaUsage(id=1,
+                                       tenant_id=FAKE_TENANT1,
+                                       resource=Resource.INSTANCES,
+                                       in_use=1,
+                                       reserved=2),
+                            QuotaUsage(id=2,
+                                       tenant_id=FAKE_TENANT1,
+                                       resource=Resource.VOLUMES,
+                                       in_use=1,
+                                       reserved=1)]
+        FAKE_QUOTAS = [Quota(tenant_id=FAKE_TENANT1,
+                             resource=Resource.INSTANCES,
+                             hard_limit=-1),
+                       Quota(tenant_id=FAKE_TENANT1,
+                             resource=Resource.VOLUMES,
+                             hard_limit=-1)]
+
+        self.mock_quota_result.all = Mock(return_value=FAKE_QUOTAS)
+        self.mock_usage_result.all = Mock(return_value=FAKE_QUOTA_USAGE)
+        QuotaUsage.save = Mock()
+        Reservation.create = Mock()
+
+        delta = {'instances': 2, 'volumes': 3}
+        self.assertIsNone(self.driver.check_quotas(FAKE_TENANT1, resources,
+                                                   delta))
+
     def test_reserve(self):
 
         FAKE_QUOTAS = [QuotaUsage(id=1,