An asynchronously executed AWS Lambda function doesn't return the result of execution. If an asynchronous invocation request is successful (i.e. there were no errors due to permissions, etc), AWS Lambda immediately returns the HTTP status code 202 ACCEPTED and bears no further responsibility for communicating any information about the outcome of this asynchronous invocation.

From the documentation of AWS Lambda Invoke action:

Response Syntax

HTTP/1.1 StatusCode
X-Amz-Function-Error: FunctionError
X-Amz-Log-Result: LogResult

Payload

Response Elements

If the action is successful, the service sends back the following HTTP response.

StatusCode

The HTTP status code will be in the 200 range for successful request. For the RequestResponse invocation type this status code will be 200. For the Event invocation type this status code will be 202. For the DryRun invocation type the status code will be 204.

[...]

The response returns the following as the HTTP body.

Payload

It is the JSON representation of the object returned by the Lambda function. This is present only if the invocation type is RequestResponse.

If you don't want to update your lambda function, just simulate APIGateway event object by boto3 client:

If your api looks like https://linktolambda/{id} (ex: https://linktolambda/123456)

You will invoke with this code:

        payload = { "pathParameters": { "id":"123456" } } 
        result = client.invoke(FunctionName=conf.lambda_function_name,
                    InvocationType='RequestResponse',                                      
                    Payload=json.dumps(payload))

Or your API look like https://linktolambda?id=123456

        payload = { "queryStringParameters": { "id":"123456" } } 
        result = client.invoke(FunctionName=conf.lambda_function_name,
                    InvocationType='RequestResponse',                                      
                    Payload=json.dumps(payload))

Manuel,

as mentioned, the return info is inside the Payload element in the returned json. Payload is a boto3 object type that you need to access it's contents through it's read() method.

The code I used to get the python dictionary that I return from my lambda functions is this:

payload = json.loads(response['Payload'].read())

statusCode = payload.get('statusCode')
message = payload.get('message')
results = payload.get('results')