Add created_datetime to schema1 format

image/docker/schema1.py

@@ -11,6 +11,8 @@ import logging
 from collections import namedtuple, OrderedDict
 from datetime import datetime
 
+import dateutil.parser
+
 from jsonschema import validate as validate_schema, ValidationError
 
 from jwkest.jws import SIGNER_ALGS, keyrep
@@ -268,6 +270,18 @@ class DockerSchema1Manifest(ManifestInterface):
   def leaf_layer(self):
     return self.layers[-1]
 
+  @property
+  def created_datetime(self):
+    created_datetime_str = self.leaf_layer.v1_metadata.created
+    if created_datetime_str is None:
+      return None
+
+    try:
+      return dateutil.parser.parse(created_datetime_str).replace(tzinfo=None)
+    except:
+      # parse raises different exceptions, so we cannot use a specific kind of handler here.
+      return None
+
   @property
   def layers(self):
     if self._layers is None: