AWS API Gateway, Python Lambda and HTTP status

Question

I'm struggling to understand how to setup proper http status codes and error messages using AWS API Gateway and a Lambda Function (python) as Integration type.

I'm working with a simple example, here the details:

Lambda function

def lambda_handler(event, context):

    return_json = {}
    if event["request-number"] == "":
        raise Exception("Error request-number can't be empty")
    elif event["request-number"] == "3":
        raise Exception("Value not accepted")
    else:
        return_json = {"service-activated": "TRUE"}

    return return_json

API /resourcetest POST

This is integrated with the lambda above.

Goal: return HTTP 400 and body with message Error request-number can't be empty when request-number = "".

Implementation:

1. I've created a new method response 400
2. In the lambda Error Regex I've mapped Error.* so to catch that string

3. In the body mapping templates: I've created a content-type as application/json and as a template I've used (there's an hashtag symbol before set, but that screw up the formatting of this page, so I've omitted it):

   set($inputRoot = $input.path('$')) { "message" : $input.json('$.errorMessage') }

4. I've checked to have the http status 400 in the method response (and I have it)

Test Through the AWS API Gateway console I've tested to have HTTP 400 and the message Error request-number can't be empty in the body. Good I achieved what I wanted:

I've decided to test also through Postman and the Chrome plugin Restlet Client and what I've got is http status 200 and error message not formatted properly:

Now, this is quite weird: from the AWS API Console all is good and nice, from an external service nothing work as expected.

Has anyone had to deal with something similar ?

Thanks!

Answer 1

Have you re-deployed your API?