Return 503 if insufficient permission on filestore

Fixes lp 919257

Return 503 "Service Unavailable" status from POST /images request
where there's insufficient permission to write image content to
the backend filestore.

Change-Id: I0c4e8bb1e70d6542852a86903a4a2a200dd23f01

glance/api/v1/images.py

@@ -30,7 +30,9 @@ from webob.exc import (HTTPError,
                        HTTPBadRequest,
                        HTTPForbidden,
                        HTTPUnauthorized,
-                       HTTPRequestEntityTooLarge)
+                       HTTPRequestEntityTooLarge,
+                       HTTPServiceUnavailable,
+                      )
 
 from glance.api import policy
 import glance.api.v1
@@ -404,6 +406,14 @@ class Controller(controller.BaseController):
             raise HTTPRequestEntityTooLarge(msg, request=req,
                                             content_type='text/plain')
 
+        except exception.StorageWriteDenied, e:
+            msg = _("Insufficient permissions on image storage media: %s") % e
+            logger.error(msg)
+            self._safe_kill(req, image_id)
+            self.notifier.error('image.upload', msg)
+            raise HTTPServiceUnavailable(msg, request=req,
+                                         content_type='text/plain')
+
         except HTTPError, e:
             self._safe_kill(req, image_id)
             self.notifier.error('image.upload', e.explanation)

glance/common/exception.py

@@ -83,6 +83,10 @@ class StorageFull(GlanceException):
     message = _("There is not enough disk space on the image storage media.")
 
 
+class StorageWriteDenied(GlanceException):
+    message = _("Permission to write image storage media denied.")
+
+
 class ImportFailure(GlanceException):
     message = _("Failed to import requested object/class: '%(import_str)s'. "
                 "Reason: %(reason)s")

glance/store/filesystem.py

@@ -208,6 +208,8 @@ class Store(glance.store.base.Store):
         except IOError as e:
             if e.errno in [errno.EFBIG, errno.ENOSPC]:
                 raise exception.StorageFull()
+            elif e.errno == errno.EACCES:
+                raise exception.StorageWriteDenied()
             else:
                 raise
 

glance/tests/unit/test_filesystem_store.py

@@ -167,6 +167,13 @@ class TestStore(base.IsolatedUnitTest):
         """
         self._do_test_add_failure(errno.EFBIG, exception.StorageFull)
 
+    def test_add_storage_write_denied(self):
+        """
+        Tests that adding an image with insufficient filestore permissions
+        raises an appropriate exception
+        """
+        self._do_test_add_failure(errno.EACCES, exception.StorageWriteDenied)
+
     def test_add_other_failure(self):
         """
         Tests that a non-space-related IOError does not raise a