/services?name=<name> API fails when using list_limit

When using list_limit configuration option in Default section of
keystone.conf, the /services?name=<service_name> API fails to find
the service if list_limit value is smaller than the total number
of services and the searched service is not among the first
'list_limit' services. The API should first filter by name and
only afterwards truncate the result list.

Also, this patch fixes setting the 'truncated' attribute of the
driver's hint.limit object when truncating the list outside of
driver_hints.truncated decorator, problem exposed by fixing the
problem described in the first paragraph.

Closes-Bug: #1594482
Change-Id: I832f542c3cb0faf94a1e5bce5a894f7f4d26a8de

keystone/common/driver_hints.py

@@ -38,7 +38,7 @@ def truncated(f):
                 _('Cannot truncate a driver call without hints list as '
                   'first parameter after self '))
 
-        if hints.limit is None:
+        if hints.limit is None or hints.filters:
             return f(self, hints, *args, **kwargs)
 
         # A limit is set, so ask for one more entry than we need

keystone/common/sql/core.py

@@ -371,7 +371,11 @@ def _limit(query, hints):
 
     # If we satisfied all the filters, set an upper limit if supplied
     if hints.limit:
-        query = query.limit(hints.limit['limit'])
+        original_len = query.count()
+        limit_query = query.limit(hints.limit['limit'])
+        if limit_query.count() < original_len:
+            hints.limit['truncated'] = True
+            query = limit_query
     return query
 
 

keystone/tests/unit/test_v3_catalog.py

@@ -345,12 +345,13 @@ class CatalogTestCase(test_v3.RestfulTestCase):
 
     def test_filter_list_services_by_name(self):
         """Call ``GET /services?name=<some name>``."""
-        target_ref = self._create_random_service()
-
         # create unrelated services
         self._create_random_service()
         self._create_random_service()
 
+        # create the desired service
+        target_ref = self._create_random_service()
+
         response = self.get('/services?name=' + target_ref['name'])
         self.assertValidServiceListResponse(response, ref=target_ref)
 
@@ -360,6 +361,12 @@ class CatalogTestCase(test_v3.RestfulTestCase):
         filtered_service = filtered_service_list[0]
         self.assertEqual(target_ref['name'], filtered_service['name'])
 
+    def test_filter_list_services_by_name_with_list_limit(self):
+        """Call ``GET /services?name=<some name>``."""
+        self.config_fixture.config(list_limit=1)
+
+        self.test_filter_list_services_by_name()
+
     def test_get_head_service(self):
         """Call ``GET & HEAD /services/{service_id}``."""
         resource_url = '/services/%(service_id)s' % {

releasenotes/notes/bug-1594482-52a5dd1d8477b694.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - >
+    [`bug 1594482 <https://bugs.launchpad.net/keystone/+bug/1594482>`_]
+    When using list_limit config option, the GET /services?name={service_name}
+    API was first truncating the list and afterwards filtering by name.
+    The API was fixed to first filter by name and only afterwards truncate the
+    result list to the desired limit.