"Bad handler 'lambda_handler': not enough values to unpack (expected 2, got 1)",

Question

I am getting this error while uploading code on lambda using docker image. I don't know what is wrong everything seems fine.

My file structure is:
-DockerFile
-myfunction.py
-requirements.txt

myfunction.py file:

try:

    import json
    import sys
    import requests
    print("All imports ok ...")
except Exception as e:
    print("Error Imports : {} ".format(e))


def lambda_handler(event, context):

    print("Hello!")
    print("event = {}".format(event))
    return {
        'statusCode': 200,
    } 

DockerFile:

FROM public.ecr.aws/lambda/python:3.8

COPY requirements.txt ./
RUN pip3 install -r requirements.txt
COPY myfunction.py ./

CMD ["myfunction.lambda_handler"]

Requirements.txt:

requests==2.25.1

Answer 1

Try this

For someone that have the same problem.

In your Dockerfile

FROM public.ecr.aws/lambda/python:3.8

# app.py is the file where is your lambda function
COPY app.py ${LAMBDA_TASK_ROOT}

# Install the function's dependencies using file requirements.txt
# from your project folder.

# To configure the libraries you can check this link:
# https://note.nkmk.me/en/python-pip-install-requirements/
COPY requirements.txt  .
RUN  pip3 install -r requirements.txt --target "${LAMBDA_TASK_ROOT}"

# Set the CMD to your handler (could also be done as a parameter override outside of the Dockerfile)

# app => filename
# handler => the function name where the program starts
CMD [ "app.handler" ] 

In your app.py file

import json
import time
import os
import logging


logger = logging.getLogger()
logger.setLevel(logging.INFO)

def handler(event, context):

    token = event["token"]
    # HERE WHEREVER YOU WANT THIS IS JUST AN EXAMPLE
    print("Use token: ",token)
    print("Lambda function ARN:", context.invoked_function_arn)
    print("CloudWatch log stream name:", context.log_stream_name)
    print("CloudWatch log group name:",  context.log_group_name)
    print("Lambda Request ID:", context.aws_request_id)
    print("Lambda function memory limits in MB:", context.memory_limit_in_mb)
    # We have added a 1 second delay so you can see the time remaining in get_remaining_time_in_millis.
    time.sleep(1)
    print("Lambda time remaining in MS:", context.get_remaining_time_in_millis())
    json_region = None
    try:
        json_region = os.environ['AWS_REGION']
    except KeyError:
        json_region = "LOCAL ENVIRONMENT"
    else:
        json_region = "REGION NOT FOUND"
    
    logger.info('Use a the logger')
    
    return {
        'statusCode': 200,
         "headers": {
            "Content-Type": "application/json"
        },
        "body": json.dumps({
            "Region ": json_region
        })
    }

Run the docker commands

Build

docker build -t yourcontainername.

Run docker run -p 9000:8080 yourcontainername

Test with CLI

curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'

Note: If you are using windows use -d "{"""token""":"""mytoken"""}"

If everything goes fine the response is something like:

{"statusCode": 200, "headers": {"Content-Type": "application/json"}, "body": "{\"Region \": \"LOCAL ENVIRONMENT\"}"}

So...

In your case the problem is your Dockerfile

Should be like:

FROM public.ecr.aws/lambda/python:3.8

COPY myfunction.py ${LAMBDA_TASK_ROOT}

COPY requirements.txt .
RUN  pip3 install -r requirements.txt --target "${LAMBDA_TASK_ROOT}"

CMD ["myfunction.lambda_handler"]

According with the docs

Install any dependencies under the ${LAMBDA_TASK_ROOT} directory alongside the function handler to ensure that the Lambda runtime can locate them when the function is invoked.

Resources

https://docs.aws.amazon.com/lambda/latest/dg/python-image.html#python-image-clients

https://docs.aws.amazon.com/lambda/latest/dg/images-create.html