Make the datetime utility function coerce to UTC

Getting datetime objects from existing sources (i.e. sqlalchemy)
is problematic because they're "timezone naive". Make the utility
function coerce these to UTC for easier conversion.

Related to blueprint unified-object-model

Change-Id: I61bc6b13f9bd9441d64cc6930e43e921af72a342

2 files changed, 17 insertions, 3 deletions

diff --git a/nova/objects/utils.py b/nova/objects/utils.py
index dd654045c..21ef6faeb 100644
--- a/nova/objects/utils.py
+++ b/nova/objects/utils.py
@@ -15,6 +15,7 @@
 """Utility methods for objects"""
 
 import datetime
+import iso8601
 import netaddr
 
 from nova.openstack.common import timeutils
@@ -22,8 +23,16 @@ from nova.openstack.common import timeutils
 
 def datetime_or_none(dt):
     """Validate a datetime or None value."""
-    if dt is None or isinstance(dt, datetime.datetime):
-        return dt
+    if dt is None:
+        return None
+    elif isinstance(dt, datetime.datetime):
+        if dt.utcoffset() is None:
+            # NOTE(danms): Legacy objects from sqlalchemy are stored in UTC,
+            # but are returned without a timezone attached.
+            # As a transitional aid, assume a tz-naive object is in UTC.
+            return dt.replace(tzinfo=iso8601.iso8601.Utc())
+        else:
+            return dt
     raise ValueError('A datetime.datetime is required here')
 
 
diff --git a/nova/tests/objects/test_objects.py b/nova/tests/objects/test_objects.py
index cbaf8cb17..e7508ba38 100644
--- a/nova/tests/objects/test_objects.py
+++ b/nova/tests/objects/test_objects.py
@@ -15,6 +15,7 @@
 import contextlib
 import datetime
 import gettext
+import iso8601
 import netaddr
 
 gettext.install('nova')
@@ -118,8 +119,12 @@ class TestMetaclass(test.TestCase):
 
 class TestUtils(test.TestCase):
     def test_datetime_or_none(self):
-        dt = datetime.datetime.now()
+        naive_dt = datetime.datetime.now()
+        dt = timeutils.parse_isotime(timeutils.isotime(naive_dt))
         self.assertEqual(utils.datetime_or_none(dt), dt)
+        self.assertEqual(utils.datetime_or_none(dt),
+                         naive_dt.replace(tzinfo=iso8601.iso8601.Utc(),
+                                          microsecond=0))
         self.assertEqual(utils.datetime_or_none(None), None)
         self.assertRaises(ValueError, utils.datetime_or_none, 'foo')