Extracted HTTP response codes to constants

There are several places in the source code where HTTP response
codes are used as numeric values.

Status codes 200, 202, 204, 300, 400, 401, 403, 404, 405, 409, 413,
415, 500, 501, 503 under api/v1 and api/v2 are replaced with symbolic
constants from six.moves.http_client thus improves code readability.
More patches will be submitted to address other status codes.

Partial-Bug: #1520159
Change-Id: I7c61122a6b043d7d238bea95ef39d8fa97817df4

cinder/api/middleware/auth.py

@@ -24,6 +24,7 @@ from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_middleware import request_id
 from oslo_serialization import jsonutils
+from six.moves import http_client
 import webob.dec
 import webob.exc
 
@@ -129,7 +130,7 @@ class NoAuthMiddleware(base_wsgi.Middleware):
             res.headers['X-Auth-Token'] = '%s:%s' % (user_id, project_id)
             res.headers['X-Server-Management-Url'] = os_url
             res.content_type = 'text/plain'
-            res.status = '204'
+            res.status_int = http_client.NO_CONTENT
             return res
 
         token = req.headers['X-Auth-Token']

cinder/api/middleware/fault.py

@@ -16,6 +16,7 @@
 
 from oslo_log import log as logging
 import six
+from six.moves import http_client
 import webob.dec
 import webob.exc
 
@@ -49,9 +50,9 @@ class FaultWrapper(base_wsgi.Middleware):
                            'error': inner})
         safe = getattr(inner, 'safe', False)
         headers = getattr(inner, 'headers', None)
-        status = getattr(inner, 'code', 500)
+        status = getattr(inner, 'code', http_client.INTERNAL_SERVER_ERROR)
         if status is None:
-            status = 500
+            status = http_client.INTERNAL_SERVER_ERROR
 
         msg_dict = dict(url=req.url, status=status)
         LOG.info("%(url)s returned with HTTP %(status)d", msg_dict)

cinder/api/openstack/wsgi.py

@@ -25,6 +25,7 @@ from oslo_utils import encodeutils
 from oslo_utils import excutils
 from oslo_utils import strutils
 import six
+from six.moves import http_client
 import webob
 import webob.exc
 
@@ -441,7 +442,7 @@ class ResponseObject(object):
 
         self.obj = obj
         self.serializers = serializers
-        self._default_code = 200
+        self._default_code = http_client.OK
         self._code = code
         self._headers = headers or {}
         self.serializer = None
@@ -1316,16 +1317,16 @@ class Controller(object):
 class Fault(webob.exc.HTTPException):
     """Wrap webob.exc.HTTPException to provide API friendly response."""
 
-    _fault_names = {400: "badRequest",
+    _fault_names = {http_client.BAD_REQUEST: "badRequest",
-                    401: "unauthorized",
+                    http_client.UNAUTHORIZED: "unauthorized",
-                    403: "forbidden",
+                    http_client.FORBIDDEN: "forbidden",
-                    404: "itemNotFound",
+                    http_client.NOT_FOUND: "itemNotFound",
-                    405: "badMethod",
+                    http_client.METHOD_NOT_ALLOWED: "badMethod",
-                    409: "conflictingRequest",
+                    http_client.CONFLICT: "conflictingRequest",
-                    413: "overLimit",
+                    http_client.REQUEST_ENTITY_TOO_LARGE: "overLimit",
-                    415: "badMediaType",
+                    http_client.UNSUPPORTED_MEDIA_TYPE: "badMediaType",
-                    501: "notImplemented",
+                    http_client.NOT_IMPLEMENTED: "notImplemented",
-                    503: "serviceUnavailable"}
+                    http_client.SERVICE_UNAVAILABLE: "serviceUnavailable"}
 
     def __init__(self, exception):
         """Create a Fault for the given webob.exc.exception."""
@@ -1344,7 +1345,7 @@ class Fault(webob.exc.HTTPException):
             fault_name: {
                 'code': code,
                 'message': i18n.translate(explanation, locale)}}
-        if code == 413:
+        if code == http_client.REQUEST_ENTITY_TOO_LARGE:
             retry = self.wrapped_exc.headers.get('Retry-After', None)
             if retry:
                 fault_data[fault_name]['retryAfter'] = retry

cinder/api/v1/snapshots.py

@@ -15,6 +15,8 @@
 
 """The volumes snapshots api."""
 
+
+from six.moves import http_client
 from webob import exc
 
 from cinder.api.openstack import wsgi
@@ -70,7 +72,7 @@ class SnapshotsController(snapshots_v2.SnapshotsController):
             super(SnapshotsController, self).detail(
                 _update_search_opts(req)))
 
-    @wsgi.response(200)
+    @wsgi.response(http_client.OK)
     def create(self, req, body):
         """Creates a new snapshot."""
         if (body is None or not body.get('snapshot') or

cinder/api/v1/volumes.py

@@ -16,6 +16,7 @@
 """The volumes api."""
 
 from oslo_log import log as logging
+from six.moves import http_client
 from webob import exc
 
 from cinder.api.openstack import wsgi
@@ -102,7 +103,7 @@ class VolumeController(volumes_v2.VolumeController):
         return _volume_v2_to_v1(
             super(VolumeController, self).detail(req))
 
-    @wsgi.response(200)
+    @wsgi.response(http_client.OK)
     def create(self, req, body):
         """Creates a new volume."""
         if (body is None or not body.get('volume') or

cinder/api/v2/limits.py

@@ -415,7 +415,7 @@ class WsgiLimiterProxy(object):
 
         resp = conn.getresponse()
 
-        if 200 >= resp.status < 300:
+        if http_client.OK >= resp.status < http_client.MULTIPLE_CHOICES:
             return None, None
 
         return resp.getheader("X-Wait-Seconds"), resp.read() or None

cinder/api/v2/snapshot_metadata.py

@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from six.moves import http_client
 import webob
 from webob import exc
 
@@ -128,7 +129,7 @@ class Controller(wsgi.Controller):
         # Not found exception will be handled at the wsgi level
         snapshot = self.volume_api.get_snapshot(context, snapshot_id)
         self.volume_api.delete_snapshot_metadata(context, snapshot, id)
-        return webob.Response(status_int=200)
+        return webob.Response(status_int=http_client.OK)
 
 
 def create_resource():

cinder/api/v2/snapshots.py

@@ -18,6 +18,7 @@
 from oslo_log import log as logging
 from oslo_utils import encodeutils
 from oslo_utils import strutils
+from six.moves import http_client
 import webob
 from webob import exc
 
@@ -64,7 +65,7 @@ class SnapshotsController(wsgi.Controller):
         snapshot = self.volume_api.get_snapshot(context, id)
         self.volume_api.delete_snapshot(context, snapshot)
 
-        return webob.Response(status_int=202)
+        return webob.Response(status_int=http_client.ACCEPTED)
 
     def index(self, req):
         """Returns a summary list of snapshots."""
@@ -108,7 +109,7 @@ class SnapshotsController(wsgi.Controller):
             snapshots = self._view_builder.summary_list(req, snapshots.objects)
         return snapshots
 
-    @wsgi.response(202)
+    @wsgi.response(http_client.ACCEPTED)
     def create(self, req, body):
         """Creates a new snapshot."""
         kwargs = {}

cinder/api/v2/volume_metadata.py

@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from six.moves import http_client
 import webob
 
 from cinder.api import common
@@ -136,7 +137,7 @@ class Controller(wsgi.Controller):
             volume,
             id,
             meta_type=common.METADATA_TYPES.user)
-        return webob.Response(status_int=200)
+        return webob.Response(status_int=http_client.OK)
 
 
 def create_resource():

cinder/api/v2/volumes.py

@@ -19,6 +19,7 @@
 from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_utils import uuidutils
+from six.moves import http_client
 import webob
 from webob import exc
 
@@ -75,7 +76,7 @@ class VolumeController(wsgi.Controller):
         # Not found exception will be handled at the wsgi level
         volume = self.volume_api.get(context, id)
         self.volume_api.delete(context, volume, cascade=cascade)
-        return webob.Response(status_int=202)
+        return webob.Response(status_int=http_client.ACCEPTED)
 
     def index(self, req):
         """Returns a summary list of volumes."""
@@ -171,7 +172,7 @@ class VolumeController(wsgi.Controller):
                 "access requested image.")
         raise exc.HTTPBadRequest(explanation=msg)
 
-    @wsgi.response(202)
+    @wsgi.response(http_client.ACCEPTED)
     def create(self, req, body):
         """Creates a new volume."""
         self.assert_valid_body(body, 'volume')