errors in activity functions does not throw a FunctionFailedException back to the orchestrator function

[asanglard-se]

Description

With python, errors in activity functions does not throw a FunctionFailedException back to the orchestrator function. It throws a raw/system exception that must be parsed, that is quite complex to analyze...

Expected behavior

Implement what is documented in Azure Durable doc :
https://learn.microsoft.com/en-us/azure/azure-functions/durable/durable-functions-error-handling?tabs=python#errors-in-activity-functions

Azure Durable framework should provide a FunctionFailedException that should allow to easly identify the inner exception that was raised by the activity function.

Actual behavior

A raw/system exception is reported. We have to parse with somethings like that get the initial message.

Relevant source code snippets

   # e is the exception
   # the second line contains a json escaped
    escaped_json = e.args[0].split("\n")[1]
    # unescape the json string
    return json.loads(escaped_json)["Message"].split(":", 1)[1].lstrip()

Known workarounds

see snippet above that is actually easy to break if Azure Durable Function change the way that they report the exception

App Details

• Durable Functions extension version (e.g. v1.8.3): 2.13.5
• Azure Functions runtime version (1.0 or 2.0): 2.0
• Programming language used: python 3.11

Screenshots

Inside application insigths, we can see such message:

Exception while executing function: Functions.entity_function_name.....
{"$type":"System.Exception, System.Private.CoreLib","ClassName":"System.Exception","Message":"".....