Is it possible to access the LambdaContext when using batch processing?

[mew1033]

If so, how? I followed the docs and my code now basically looks like this:

processor = BatchProcessor(event_type=EventType.SQS)


def record_handler(record: SQSRecord):
    """
    Handler for a single SQS record.
    """
    # Do some cool things with record.
    pass


@logger.inject_lambda_context
@event_source(data_class=SQSEvent)
@batch_processor(record_handler=record_handler, processor=processor)
def lambda_handler(event: Dict[str, SQSEvent], context: LambdaContext) -> Dict[str, Any]:
    return processor.response()

Is there any way to access the context object in the record_handler function? I'm having a hard time searching for the answer because every time I mention context and batch processing, all I find is how to do batch processing with the context manager method.

[michaelbrewer]

A work around would look something like this:

processor = BatchProcessor(event_type=EventType.SQS)


def lambda_handler(event, context: LambdaContext):
    def record_handler(record: SQSRecord):
        print(context.function_name)
        ...

    with processor(records=event["Records"], handler=record_handler):
        processor.process()

    return processor.response()

FYI, your code example typing for event should be SQSEvent

[mew1033]

Ah, I guess that'd work. I do wish there was a way to pass the LambdaContext into the record_handler directly.

And thanks for the tip on the event typing. I definitely missed that.

[heitorlessa]

Hey @mew1033, What information are you looking to use within Lambda Context?

Lambda runtime makes key Lambda Context data available as environment variables. If these are insufficient, please open up a feature request as it might be an useful exercise to think of ways to expose Lambda Context more generally across any utility.

Thank you!

[mew1033]

I'm looking to use the get_remaining_time_in_millis function specifically. In this case, the reason is that my batch size sometimes includes very large items that might time out if they are at the end of the batch. I want to add something to the top of the record_handler that checks the remaining time, and if it's below a threshold it just raises an exception for that record. Then the partial failure mechanism can put the failed items back on the queue.

As it is right now, if the function just times out, everything is put back, not just the failed items.

[michaelbrewer]

makes sense.

[heitorlessa]

Closing as this was released back then: https://docs.powertools.aws.dev/lambda/python/latest/utilities/batch/#accessing-lambda-context