Bug: `log_uncaught_exceptions` only works locally and not on lambda

[bellis-ai]

Expected Behaviour

When log_uncaught_exceptions=True, uncaught exceptions in a lambda are handled and transformed to a structured log.

Current Behaviour

Uncaught exceptions are printed unstructured.

Code snippet

from aws_lambda_powertools import Logger
from aws_lambda_powertools.utilities.typing import LambdaContext

logger = Logger(log_uncaught_exceptions=True)

def lambda_handler(event: dict, context: LambdaContext) -> str:
    raise(Exception("asdf"))

Possible Solution

Probably none. Document this behavior.

I don't think sys.excepthook can be overridden in a lambda container, but I have no proof because the original forum thread that details this has been deleted by AWS with no replacement.

Steps to Reproduce

Set log_uncaught_exceptions=True in an actual running lambda. If log_uncaught_exceptions=True on a local machine, the behavior runs just as intended.

AWS Lambda Powertools for Python version

latest

AWS Lambda function runtime

3.9

Packaging format used

Lambda Layers

Debugging logs

No response

[boring-cyborg]

Thanks for opening your first issue here! We'll come back to you as soon as we can.
In the meantime, check out the #python channel on our AWS Lambda Powertools Discord: Invite link

[bellis-ai]

Crossposted this on the re:Post forum: https://repost.aws/questions/QUlMvn9vDzRiyDsGnQ0SoztQ/how-do-i-override-the-sys-excepthook-in-a-lambda-python-container

[leandrodamascena]

Hello @bellis-ai. Thanks for reporting this bug and posting the helpful links for review. We were able to reproduce the error in our local tests and are looking into how to resolve it. This failure was most likely because we made this update and we didn't have E2E tests for it.

We'll be back with an update here as soon as possible.

[leandrodamascena]

Coming back here with feedback. We tried to find a solution and ran into the same problem: we couldn't get the excepthook to work inside the Lambda runtime and we couldn't catch exceptions using log_uncaught_exceptions=True.
We are reaching out internally to the Lambda team to understand if there is any workaround to do in this case or if we are missing something.

Not sure if this is suitable for you, but for now you can use Middleware Factory to catch all exceptions and log them centrally. We had a discussion about this on our Discord Server and it might be helpful in your case.

Thank you for your patience @bellis-ai and we are working to resolve this as soon as possible.

[leandrodamascena]

Updating this issue...
We're working closely with the Lambda team to investigate the issue and determine if we have a workaround to resolve the issue.

I'll come back here as soon as I have an update. In the meantime, I'll update the documentation to suggest not using this code in production and putting this issue in a blocking state.

[heitorlessa]

Update: @leandrodamascena updated the docs!

Adding this to our board of activities so we can do bi-weekly follow ups with the Lambda team - (no update beyond acknowledge yet).