diff --git a/magnum/api/controllers/root.py b/magnum/api/controllers/root.py
index 0d29117dd..64eaf9979 100644
--- a/magnum/api/controllers/root.py
+++ b/magnum/api/controllers/root.py
@@ -94,7 +94,7 @@ def get(self):
         return Root.convert()
 
     @pecan.expose()
-    def _route(self, args):
+    def _route(self, args, request):
         """Overrides the default routing behavior.
 
         It redirects the request to the default version of the magnum API
diff --git a/magnum/api/controllers/v1/__init__.py b/magnum/api/controllers/v1/__init__.py
index a8d694105..dec6c4f9c 100644
--- a/magnum/api/controllers/v1/__init__.py
+++ b/magnum/api/controllers/v1/__init__.py
@@ -211,7 +211,7 @@ def _check_version(self, version, headers=None):
                 min_version=str(MIN_VER))
 
     @pecan.expose()
-    def _route(self, args):
+    def _route(self, args, request):
         version = ver.Version(
             pecan.request.headers, MIN_VER_STR, MAX_VER_STR)
 
diff --git a/magnum/api/controllers/v1/cluster_template.py b/magnum/api/controllers/v1/cluster_template.py
index c45ef4de7..59c5a1d67 100644
--- a/magnum/api/controllers/v1/cluster_template.py
+++ b/magnum/api/controllers/v1/cluster_template.py
@@ -435,10 +435,14 @@ def post(self, cluster_template):
         # check root volume size
         boot_volume_size = cluster_template_dict['labels'].get(
             'boot_volume_size', CONF.cinder.default_boot_volume_size)
-        attr_validator.validate_flavor_root_volume_size(
-            cli, cluster_template_dict['flavor_id'], boot_volume_size)
-        attr_validator.validate_flavor_root_volume_size(
-            cli, cluster_template_dict['master_flavor_id'], boot_volume_size)
+        if 'flavor_id' in cluster_template_dict:
+            attr_validator.validate_flavor_root_volume_size(
+                cli, cluster_template_dict['flavor_id'], boot_volume_size)
+        if 'master_flavor_id' in cluster_template_dict:
+            attr_validator.validate_flavor_root_volume_size(
+                cli,
+                cluster_template_dict['master_flavor_id'],
+                boot_volume_size)
 
         if (cluster_template.docker_storage_driver in ('devicemapper',
                                                        'overlay')):
diff --git a/magnum/tests/unit/api/controllers/v1/test_cluster_template.py b/magnum/tests/unit/api/controllers/v1/test_cluster_template.py
index eeae713c7..f085ba656 100644
--- a/magnum/tests/unit/api/controllers/v1/test_cluster_template.py
+++ b/magnum/tests/unit/api/controllers/v1/test_cluster_template.py
@@ -1135,6 +1135,19 @@ def test_create_cluster_template_with_flavor(self,
         self.assertEqual(bdict['master_flavor_id'],
                          response.json['master_flavor_id'])
 
+    @mock.patch('magnum.api.attr_validator.validate_image')
+    def test_create_cluster_template_without_flavor(self,
+                                                    mock_image_data):
+        mock_image_data.return_value = {'name': 'mock_name',
+                                        'os_distro': 'fedora-coreos'}
+        bdict = apiutils.cluster_template_post_data()
+        del bdict['flavor_id']
+        del bdict['master_flavor_id']
+        response = self.post_json('/clustertemplates', bdict)
+        self.assertEqual(201, response.status_int)
+        self.assertIsNone(response.json['flavor_id'])
+        self.assertIsNone(response.json['master_flavor_id'])
+
     @mock.patch('magnum.api.attr_validator.validate_image')
     def test_create_cluster_template_with_no_exist_flavor(self,
                                                           mock_image_data):