[Feature Request][Bug?] Request-scope LoggingUtils setting of keys

[humanzz]

Is your feature request related to a problem? Please describe.
My team uses Powertools core utilities (Logging, Metrics and Tracing) in one of our Lambda functions.
In that, we rely on LoggingUtils.appendKeys and metricsLogger().putProperty to append specific request-related key/value pairs that improve our ability to debug issues and run adhoc queries using CloudWatch Logs Insights.

We've discovered an issue with our logging that values set via LoggingUtils.appendKeys are not cleared after the request is done, they instead get carried over to the following requests unless those key/value pairs are overridden which led to wrong key/value pairs being associated with a given request's log lines.

This is an unexpected behaviour, our assumption was that logging properties set in a given request, would just be scoped to that request.

Describe the solution you'd like
Setting logging properties via LoggingUtils.appendKeys should be scoped to a request i.e. they should be automatically cleared after the request is completed.

The behaviour where properties are carried over from one request to the next, opens a door for logging bugs as in Lambda.

Describe alternatives you've considered
The main alternative, and current mitigation, is to explicitly clear the logging properties using LoggingUtils.removeKeys. While it achieves the same result, it's cumbersome - as it requires tracking the keys to clear.

[humanzz]

I've had a look at both Java and Python versions documentation

• Java: https://awslabs.github.io/aws-lambda-powertools-java/core/logging.html#appending-additional-keys
• Python: https://awslabs.github.io/aws-lambda-powertools-python/latest/core/logger/#appending-additional-keys

The python version's documentation is clear about the expected behaviour but also provides a way to achieve the behaviour I described as desired https://awslabs.github.io/aws-lambda-powertools-python/latest/core/logger/#clearing-all-state

[pankajagrawal16]

Thanks for opening the issue and findings. I will bring in feature parity with python version 👍🏼

[pankajagrawal16]

@humanzz Here you go! #453

[humanzz]

This is great! Thanks a lot for the quick action @pankajagrawal16

A small question, this should work even if LoggingUtils.appendKeys call is made outside of the handler function, right? As along as it's within the same thread (ThreadContext), right?

[pankajagrawal16]

This is great! Thanks a lot for the quick action @pankajagrawal16

A small question, this should work even if LoggingUtils.appendKeys call is made outside of the handler function, right? As along as it's within the same thread (ThreadContext), right?

Yes it will work either way, since we are clearing the MDC context of log4j