1 files changed, 35 insertions, 0 deletions
diff --git a/keystoneclient/utils.py b/keystoneclient/utils.py
index 300ca54..5017431 100644
--- a/keystoneclient/utils.py
+++ b/keystoneclient/utils.py
@@ -18,6 +18,7 @@ import logging
 import sys
 
 from oslo_utils import encodeutils
+from oslo_utils import timeutils
 import prettytable
 import six
 
@@ -336,3 +337,37 @@ class positional(object):
             return func(*args, **kwargs)
 
         return inner
+
+
+_ISO8601_TIME_FORMAT_SUBSECOND = '%Y-%m-%dT%H:%M:%S.%f'
+_ISO8601_TIME_FORMAT = '%Y-%m-%dT%H:%M:%S'
+
+
+def isotime(at=None, subsecond=False):
+    """Stringify time in ISO 8601 format."""
+
+    # Python provides a similar instance method for datetime.datetime objects
+    # called isoformat(). The format of the strings generated by isoformat()
+    # have a couple of problems:
+    # 1) The strings generated by isotime are used in tokens and other public
+    #    APIs that we can't change without a deprecation period. The strings
+    #    generated by isoformat are not the same format, so we can't just
+    #    change to it.
+    # 2) The strings generated by isoformat do not include the microseconds if
+    #    the value happens to be 0. This will likely show up as random failures
+    #    as parsers may be written to always expect microseconds, and it will
+    #    parse correctly most of the time.
+
+    if not at:
+        at = timeutils.utcnow()
+    st = at.strftime(_ISO8601_TIME_FORMAT
+                     if not subsecond
+                     else _ISO8601_TIME_FORMAT_SUBSECOND)
+    tz = at.tzinfo.tzname(None) if at.tzinfo else 'UTC'
+    st += ('Z' if tz == 'UTC' else tz)
+    return st
+
+
+def strtime(at=None):
+    at = at or timeutils.utcnow()
+    return at.strftime(timeutils.PERFECT_TIME_FORMAT)