Better logging for freezer ui

Add a LOG.error(error.message) in the shield decorator to save those
logs in case of an exception.

Resolves bug: 1532772

Change-Id: Ic43a5a7eb048512f6079e56e2230aaa954a1449d

disaster_recovery/utils.py

@@ -10,6 +10,8 @@
 #  License for the specific language governing permissions and limitations
 #  under the License.
 
+import logging
+
 import datetime
 import uuid
 import re
@@ -23,6 +25,9 @@ from django.utils.translation import ugettext_lazy as _
 from horizon import exceptions
 
 
+LOG = logging.getLogger(__name__)
+
+
 def create_dict(**kwargs):
     """Create a dict only with values that exists so we avoid send keys with
     None values
@@ -181,7 +186,8 @@ def shield(message, redirect=''):
 
             try:
                 return function(request, *args, **kwargs)
-            except Exception:
+            except Exception as error:
+                LOG.error(error.message)
                 namespace = "horizon:disaster_recovery:"
                 r = reverse("{0}{1}".format(namespace, redirect))
                 exceptions.handle(request, _(message), redirect=r)