Lambda Handler to invoke Python script directly-CodePudding

I'm not a Python developer but I got stuck with taking over the maintenance of a Python 3.9 project that currently runs as a cronjob on an EC2 instance. I need to get it running from AWS Lambda. Currently the crontab on the EC2 instance invokes a cronjob/run.py script that looks a little like this:

import os
import sys

from dotenv import load_dotenv
load_dotenv()
sync_events = get_sync_events()
# lots more stuff down here

The important thing here is that there is no __main__ method invoked. The crontab just treats this Python source file like a script and executes it from top to bottom.

My understanding is that the Lambda Handler needs a main method to be invoked. So I need a way to run the existing cronjob/run.py (that again, has no main entry point) from inside the Lambda Handler, somehow:

def lambda_handler(event, context):
    try:
        # run everything thats in cronjob/run.py right here
        raise e
    except Exception as e:
        raise e

if __name__ == '__main__':
    lambda_handler(None, None)

So my question: do I need my Lambda Handler to have a __main__ method like the above, or is it possible to configure my Lambda to just call cronjob/run.py directly? If not, what are the best options here? Thanks in advance!

CodePudding user response：

do I need my Lambda Handler to have a main method

No, you don't.

If you just want to run run.py with lambda, you can keep things simple and just use:

import os
import sys
from dotenv import load_dotenv

def main(event, context):         
    load_dotenv()
    sync_events = get_sync_events()
    # lots more stuff down here

and configure the lambda function to have run.main as the handler.

The name of the handler function, in this case main, can be anything, but it must have event and context as arguments.

You can find more information on lambda handler here: https://docs.aws.amazon.com/lambda/latest/dg/python-handler.html