Return an error response if the specified flavor does not exists. (v4)

'nova list --flavor <id>' command outputs empty list, if there is not
any instance or flavor. A user cannot know the reason of empty list easily.
This patch changes a response to error if the specified flavor-id does not
exist instead of empty list.

Example:
 $ nova flavor-list
 +----+-----------+-----------+------+-----------+------+-------+-------------+-----------+-------------+
 | ID | Name      | Memory_MB | Disk | Ephemeral | Swap | VCPUs | RXTX_Factor | Is_Public | extra_specs |
 +----+-----------+-----------+------+-----------+------+-------+-------------+-----------+-------------+
 | 1  | m1.tiny   | 512       | 0    | 0         |      | 1     | 1.0         | True      | {}          |
 | 2  | m1.small  | 2048      | 20   | 0         |      | 1     | 1.0         | True      | {}          |
 | 3  | m1.medium | 4096      | 40   | 0         |      | 2     | 1.0         | True      | {}          |
 | 4  | m1.large  | 8192      | 80   | 0         |      | 4     | 1.0         | True      | {}          |
 | 5  | m1.xlarge | 16384     | 160  | 0         |      | 8     | 1.0         | True      | {}          |
 +----+-----------+-----------+------+-----------+------+-------+-------------+-----------+-------------+

Before applying this patch:
 $ nova list --flavor 10

 $

After applying this patch:
 $ nova list --flavor 10
 ERROR: Flavor could not be found (HTTP 422) (Request-ID: req-003d4bbc-f338-4361-9eeb-1cf18073a5a8)
 $

Changelog of v4:
 * Change a response code of NotFoundFlavor from 404 to 422.

Changelog of v3:
 * Merge patchset2(change a response of test_get_all_by_flavor) into one patch.
 * Change a response code of NotFoundFlavor from 400 to 404.

Fixes bug 1076863
Change-Id: I45f35ae6a4bf1de734c258ef819fb9b4d7f9681e

3 files changed, 9 insertions, 8 deletions

diff --git a/nova/api/openstack/compute/servers.py b/nova/api/openstack/compute/servers.py
index 2c22ccc48..8c59b5092 100644
--- a/nova/api/openstack/compute/servers.py
+++ b/nova/api/openstack/compute/servers.py
@@ -536,6 +536,9 @@ class Controller(wsgi.Controller):
         except exception.MarkerNotFound as e:
             msg = _('marker [%s] not found') % marker
             raise webob.exc.HTTPBadRequest(explanation=msg)
+        except exception.FlavorNotFound as e:
+            msg = _("Flavor could not be found")
+            raise webob.exc.HTTPUnprocessableEntity(explanation=msg)
 
         if is_detail:
             self._add_instance_faults(context, instance_list)
diff --git a/nova/compute/api.py b/nova/compute/api.py
index 6da04c97b..948cf3fea 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -1122,11 +1122,8 @@ class API(base.Base):
         filters = {}
 
         def _remap_flavor_filter(flavor_id):
-            try:
-                instance_type = instance_types.get_instance_type_by_flavor_id(
-                        flavor_id)
-            except exception.FlavorNotFound:
-                raise ValueError()
+            instance_type = instance_types.get_instance_type_by_flavor_id(
+                    flavor_id)
 
             filters['instance_type_id'] = instance_type['id']
 
diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index 662a90be4..b7ef65c8e 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -4222,9 +4222,10 @@ class ComputeAPITestCase(BaseTestCase):
                 search_opts={'flavor': 5})
         self.assertEqual(len(instances), 0)
 
-        # ensure unknown filter maps to an empty list, not an exception
-        instances = self.compute_api.get_all(c, search_opts={'flavor': 99})
-        self.assertEqual(instances, [])
+        # ensure unknown filter maps to an exception
+        self.assertRaises(exception.FlavorNotFound,
+                          self.compute_api.get_all, c,
+                          search_opts={'flavor': 99})
 
         instances = self.compute_api.get_all(c, search_opts={'flavor': 3})
         self.assertEqual(len(instances), 1)