Ensure compatibility with all versions of gnocchiclient.

This makes sure that the gnocchi storage backend is compatible with all
versions of gnocchiclient. Starting with version 5.0.0 (which is not stable
yet), it returns python datetime objects instead of timestamps
(see c14f5a484d).

As soon as a gnocchiclient version > to 4.0 is considered stable, the try/except
block can be removed and a constraint python-gnocchiclient>=5.0 may be set in
requirements.txt.

Change-Id: If1816b6926e8048ff05908a15fc0870050a5718a

cloudkitty/storage/gnocchi/__init__.py

@@ -254,9 +254,15 @@ class GnocchiStorage(storage.BaseStorage):
         except gexceptions.MetricNotFound:
             return
         if len(r) > 0:
-            # (aolwas) According http://gnocchi.xyz/rest.html#metrics,
-            # gnocchi always returns measures ordered by timestamp
-            return ck_utils.dt2ts(dateutil.parser.parse(r[-1][0]))
+            # NOTE(lukapeschke) Since version 5.0.0, gnocchiclient returns a
+            # datetime object instead of a timestamp. This fixture is made
+            # to ensure compatibility with all versions
+            try:
+                # (aolwas) According http://gnocchi.xyz/rest.html#metrics,
+                # gnocchi always returns measures ordered by timestamp
+                return ck_utils.dt2ts(dateutil.parser.parse(r[-1][0]))
+            except TypeError:
+                return ck_utils.dt2ts(r[-1][0])
 
     def get_total(self, begin=None, end=None, tenant_id=None,
                   service=None, groupby=None):
@@ -316,9 +322,16 @@ class GnocchiStorage(storage.BaseStorage):
             project_id=None)
 
     def _to_cloudkitty(self, res_type, resource_data, measure):
-        begin = dateutil.parser.parse(measure[0])
-        end = (dateutil.parser.parse(measure[0]) +
-               datetime.timedelta(seconds=self._period))
+        # NOTE(lukapeschke) Since version 5.0.0, gnocchiclient returns a
+        # datetime object instead of a timestamp. This fixture is made
+        # to ensure compatibility with all versions
+        try:
+            begin = dateutil.parser.parse(measure[0])
+            end = (dateutil.parser.parse(measure[0]) +
+                   datetime.timedelta(seconds=self._period))
+        except TypeError:
+            begin = measure[0]
+            end = begin + datetime.timedelta(seconds=self._period)
         cost = decimal.Decimal(measure[2])
         # Rating informations
         rating_dict = {}