CFN: add support for passing objects in GetAtt (#13206)

pinzon · baermat · commit eec5754e6343 · 2025-10-13T10:39:46.000+02:00
diff --git a/localstack-core/localstack/services/cloudformation/engine/v2/change_set_model_preproc.py b/localstack-core/localstack/services/cloudformation/engine/v2/change_set_model_preproc.py
@@ -276,10 +276,10 @@ def _deployed_property_value_of(
         property_value: Any | None = get_value_from_path(properties, property_name)
 
         if property_value:
-            if not isinstance(property_value, (str, list)):
-                # TODO: is this correct? If there is a bug in the logic here, it's probably
-                #  better to know about it with a clear error message than to receive some form
-                #  of message about trying to use a dictionary in place of a string
+            if not isinstance(property_value, (str, list, dict)):
+                # Str: Standard expected type. TODO validate bools and numbers
+                # List: Multiple resource types can return a list of values e.g. AWS::EC2::VPC.
+                # Dict: Custom resources in CloudFormation can return arbitrary data structures.
                 raise RuntimeError(
                     f"Accessing property '{property_name}' from '{resource_logical_id}' resulted in a non-string value nor list"
                 )
