Error when I'm invoking an AWS lambda, using python. Error: positional arguments but 2 were given

Question

I'm using a lambda to invoke another one with this piece of code:

import boto3
import json

# Lambda Handler
def lambla_handler(event,context):

    lam = boto3.client('lambda', region_name='sa-east-1')

    try:
        response = lam.invoke(FunctionName='water_types', InvocationType='RequestResponse') 
    except Exception as e:
        print(e)
        raise e
    print(response)

Everything is working fine, however when the lambda 'water_types' is getting this error:

water_types() takes 0 positional arguments but 2 were given: TypeError
Traceback (most recent call last):
File "/var/runtime/awslambda/bootstrap.py", line 250, in handle_event_request
result = request_handler(json_input, context)
TypeError: water_types() takes 0 positional arguments but 2 were given

As I can see, I'm not sending any arguments. Any idea how to fix it?

def water_types(): 
   return print("water updated: 90")

Can you please show the handler of water_types? I thinks you're missing the mandatory (event, context) arguments — yorodm
– yorodm, Commented Apr 8, 2019 at 19:39

yorodm · Accepted Answer · 2019-04-08 19:55:37Z

3

If water_types is the handler of a function (which according to your code it is) you need to follow AWS guidelines on how to create lambda functions with Python

A lambda handler needs to have an structure similar to

def handler_name(event, context): 
    ...
    return some_value

The lambda runtime will provide values for event and context when it calls the handler.

So TL;DR, your function needs to look like this

def water_types(event, context): 
   return print("water updated: 90")

You're not required to do anything with those parameters, but they need to be there.

answered Apr 8, 2019 at 19:55

yorodm

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