Missing handler error in AWS Lambda

Question

My apologies for basic question. I am completely new to AWS as well as Python. I am trying to do sample code given in https://boto3.readthedocs.io/en/latest/guide/migrations3.html#accessing-a-bucket but facing a error.

import botocore
import boto3
s3 = boto3.resource('s3')
bucket = s3.Bucket('bucketname')
exists = True


try:
    s3.meta.client.head_bucket(Bucket='bucketname')
except botocore.exceptions.ClientError as e:
    # If a client error is thrown, then check that it was a 404 error.
    # If it was a 404 error, then the bucket does not exist.
    error_code = int(e.response['Error']['Code'])
    if error_code == 404:
        exists = False

Error in logs is

"errorMessage": "Handler 'lambda_handler' missing on module 'lambda_function'"

Possible duplicate - stackoverflow.com/questions/40741822/… — Rishikesh Dhokare
– Rishikesh Dhokare, Commented Jan 15, 2018 at 15:39

krishna_mee2004 · Accepted Answer · 2018-01-15 15:43:18Z

48

You need to define a function in your code. The code is missing the function named lambda_handler. Your code should look like:

    import botocore
    import boto3

    def lambda_handler(event, context):
        s3 = boto3.resource('s3')
        bucket = s3.Bucket('bucketname')
        exists = True

        try:
            s3.meta.client.head_bucket(Bucket='bucketname')
        except botocore.exceptions.ClientError as e:
            # If a client error is thrown, then check that it was a 404 error.
            # If it was a 404 error, then the bucket does not exist.
            error_code = int(e.response['Error']['Code'])
            if error_code == 404:
                exists = False

answered Jan 15, 2018 at 15:43

krishna_mee2004

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Comments

Lalit Kumar B · Accepted Answer · 2022-05-09 16:50:23Z

7

Move your code inside a python function. You can give it any name but that will become your handler. Go to lambda function basic settings and change the default handler to <yourfilename>_<yourfunctionname>. By default when you create a lambda function, the file name will be lambda_function_name.py (you can change it) and your handler method will be lambda_handler (you can change it), so the entry point is lambda_function_name.lambda_handler.

edited May 9, 2022 at 16:50

Lalit Kumar B

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answered Sep 30, 2020 at 14:31

ajith633

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Comments

LJᛃ · Accepted Answer · 2018-12-27 18:15:56Z

-6

Kishna_mee2004 is right you need to define lambda_handler without this it never work but if you getting below error:

Handler 'py' missing on module 'jobdata_rdcmedia_s3_Etl_job_scheduler_lambda': 'module' object has no attribute 'py'

Then you need to check handler info whether you have mention lambda_function_name.lambda_handler or not.

edited Dec 27, 2018 at 18:15

LJᛃ

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answered Dec 27, 2018 at 16:50

ashutosh singh

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