When the glance client throws an Exception at Horizon, catch it and determine if it is an HTTP exception. If it is, recast it as a glance_client.ClientConnectionError so that Horizon can deal with it in a better manner. Fixes 951200

Change-Id: I7cbfa74d340d25d523ab8fb18138f5cf7d33a9d9

horizon/api/glance.py

@@ -20,10 +20,14 @@
 
 from __future__ import absolute_import
 
+import functools
 import logging
 import urlparse
 
+from django.utils.decorators import available_attrs
+
 from glance import client as glance_client
+from glance.common import exception as glance_exception
 
 from horizon.api.base import APIDictWrapper, url_for
 
@@ -31,6 +35,27 @@ from horizon.api.base import APIDictWrapper, url_for
 LOG = logging.getLogger(__name__)
 
 
+def catch_glance_exception(func):
+    """
+    The glance client sometimes throws ``Exception`` classed exceptions for
+    HTTP communication issues. Catch those, and rethrow them as
+    ``glance_client.ClientConnectionErrors`` so that we can do something
+    useful with them.
+    """
+    # TODO(johnp): Remove this once Bug 952618 is fixed in the glance client.
+    @functools.wraps(func, assigned=available_attrs(func))
+    def inner_func(*args, **kwargs):
+        try:
+            return func(*args, **kwargs)
+        except Exception as exc:
+            exc_message = str(exc)
+            if('Unknown error occurred' in exc_message or
+                    'Internal Server error' in exc_message):
+                raise glance_exception.ClientConnectionError(exc_message)
+            raise
+    return inner_func
+
+
 class Image(APIDictWrapper):
     """
     Wrapper around glance image dictionary to make it object-like and provide
@@ -58,6 +83,7 @@ class ImageProperties(APIDictWrapper):
              'project_id', 'ramdisk_id', 'image_type']
 
 
+@catch_glance_exception
 def glanceclient(request):
     o = urlparse.urlparse(url_for(request, 'image'))
     LOG.debug('glanceclient connection created for host "%s:%d"' %
@@ -67,14 +93,17 @@ def glanceclient(request):
                                 auth_tok=request.user.token)
 
 
+@catch_glance_exception
 def image_create(request, image_meta, image_file):
     return Image(glanceclient(request).add_image(image_meta, image_file))
 
 
+@catch_glance_exception
 def image_delete(request, image_id):
     return glanceclient(request).delete_image(image_id)
 
 
+@catch_glance_exception
 def image_get(request, image_id):
     """
     Returns the actual image file from Glance for image with
@@ -83,6 +112,7 @@ def image_get(request, image_id):
     return glanceclient(request).get_image(image_id)[1]
 
 
+@catch_glance_exception
 def image_get_meta(request, image_id):
     """
     Returns an Image object populated with metadata for image
@@ -91,16 +121,19 @@ def image_get_meta(request, image_id):
     return Image(glanceclient(request).get_image_meta(image_id))
 
 
+@catch_glance_exception
 def image_list_detailed(request):
     return [Image(i) for i in glanceclient(request).get_images_detailed()]
 
 
+@catch_glance_exception
 def image_update(request, image_id, image_meta=None):
     image_meta = image_meta and image_meta or {}
     return Image(glanceclient(request).update_image(image_id,
                                                   image_meta=image_meta))
 
 
+@catch_glance_exception
 def snapshot_list_detailed(request):
     filters = {}
     filters['property-image_type'] = 'snapshot'

horizon/tests/api_tests/glance_tests.py

@@ -18,6 +18,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from glance.common import exception as glance_exception
+
 from horizon import api
 from horizon import test
 
@@ -56,6 +58,35 @@ class GlanceApiTests(test.APITestCase):
             self.assertIsInstance(image, api.glance.Image)
             self.assertIn(image._apidict, images)
 
+    def test_glance_exception_wrapping_for_internal_server_errors(self):
+        """
+        Verify that generic "Exception" classed exceptions from the glance
+        client's HTTP Internal Service Errors get converted to
+        ClientConnectionError's.
+        """
+        # TODO(johnp): Remove once Bug 952618 is fixed in the glance client.
+        glanceclient = self.stub_glanceclient()
+        glanceclient.get_images_detailed().AndRaise(
+                Exception("Internal Server error: "))
+        self.mox.ReplayAll()
+
+        with self.assertRaises(glance_exception.ClientConnectionError):
+            api.image_list_detailed(self.request)
+
+    def test_glance_exception_wrapping_for_generic_http_errors(self):
+        """
+        Verify that generic "Exception" classed exceptions from the glance
+        client's HTTP errors get converted to ClientConnectionError's.
+        """
+        # TODO(johnp): Remove once Bug 952618 is fixed in the glance client.
+        glanceclient = self.stub_glanceclient()
+        glanceclient.get_images_detailed().AndRaise(
+                Exception("Unknown error occurred! 503 Service Unavailable"))
+        self.mox.ReplayAll()
+
+        with self.assertRaises(glance_exception.ClientConnectionError):
+            api.image_list_detailed(self.request)
+
 
 class ImageWrapperTests(test.TestCase):
     """ Tests for wrapper classes since they have extra logic attached. """