Expected Behaviour

The logger_handler argument for a Logger instance should set the provided logger as the registered handler, regardless of what handlers are already set on logging.getLogger() outputs.

Current Behaviour

When providing a custom logger via the logger_handler argument, the custom log handler is ignored when the logger returned by logging.getLogger(name) already has a handler configured. This is problematic since environments like Serverless Framework cause getLogger to return a logger with a StreamHandler preconfigured.

Code snippet

from logging import Handler
from aws_lambda_powertools import Logger

class CustomHandler(Handler):
    """
    A custom handler class. (Truncated for clarity, contents don't matter)
    """
logger = Logger(logger_handler=CustomHandler())
print(logger.registered_handler) # This prints <StreamHandler <stdout> (NOTSET)>

def handler(event, context):
    print("Lambda running")

Possible Solution

aws_lambda_powertools can override getLogger default handlers, with or without user-provided arguments, instead of assuming the returned logger's handler list is empty.

Steps to Reproduce

1. Create a custom log handler
2. Create a Logger instance using the custom handler in the logging_handler parameter.
3. Deploy and run lambda using Serverless Framework with serverless-python-requirements in a lambda layer config.

Powertools for AWS Lambda (Python) version

latest

AWS Lambda function runtime

3.10

Packaging format used

Lambda Layers

Debugging logs

No response