AWS Lambda function template

lambda_template.py

#!/usr/bin/env python
"""Describe the function

The following environment variables can be used to steer behavior:
  - LOGLEVEL:        set the loglevel (INFO when not defined / missing), this
                     is based on the Python `logging` module
"""
import logging
import os

# setup logging, the environment variabel LOGLEVEL
# can be used for a (non-default) loglevel
DEFINED_LOGLEVELS = {
    'CRITICAL': logging.CRITICAL,
    'ERROR': logging.ERROR,
    'WARNING': logging.WARNING,
    'INFO': logging.INFO,
    'DEBUG': logging.DEBUG,
    'DEFAULT': logging.INFO
}
LOGGER = logging.getLogger()
LOGLEVEL = os.getenv('LOGLEVEL', 'DEFAULT')
if LOGLEVEL.upper() in DEFINED_LOGLEVELS:
    LOGGER.setLevel(DEFINED_LOGLEVELS[LOGLEVEL])
else:
    LOGGER.setLevel(DEFINED_LOGLEVELS['DEFAULT'])


def lambda_handler(event, context):
    """Lambda handler doing the work.
    
    For the Python programming model, see:
        http://docs.aws.amazon.com/lambda/latest/dg/python-programming-model.html

    :type event: dict
    :param event: AWS Lambda uses this parameter to pass in event data to the
        handler. This parameter is usually of the Python `dict` type. It can
        also be `list`, `str`, `int`, `float`, or `NoneType` type.

    :type event:  LambdaContext
    :param event: AWS Lambda uses this parameter to provide runtime
        information to your handler.
        See: http://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html

    :rtype: dict
    :return: Optional return of the handler. What happens to the returned value
        depends on the invocation type you use when invoking the Lambda function.
        See: http://docs.aws.amazon.com/lambda/latest/dg/python-programming-model-handler-types.html
    """
    # do the work
    
    return {'result': 'some message or data'}


if __name__ == '__main__':
    os.environ[LOGLEVEL] = 'DEBUG'
    loglevel = logging.DEBUG
    LOGGER.setLevel(loglevel)
    console_handler = logging.StreamHandler()
    console_handler.setFormatter(logging.Formatter("%(asctime)s [%(levelname)s] %(message)s"))
    console_handler.setLevel(loglevel)
    LOGGER.addHandler(console_handler)
    lambda_handler(None, None)