AWS Lambda function to call API Gateway with IAM auth

lambda_function.py

# Note: Allow Lambda action "execute-api:*" on your AWS API Gateway resources

import os
import requests
from requests_aws4auth import AWS4Auth

REGION = 'ap-southeast-2'
METHOD = 'POST'
SERVICE = 'execute-api'
DATA = {'key':'value'}
URL = "https://xyz.execute-api.ap-southeast-2.amazonaws.com/stage/method"

def handler(event,context):
  aws_auth = AWS4Auth(
    os.environ['AWS_ACCESS_KEY_ID'],
    os.environ['AWS_SECRET_ACCESS_KEY'],
    REGION,
    SERVICE,
    session_token=os.environ['AWS_SESSION_TOKEN']
  )
  r = requests.request(METHOD, URL,data=DATA,auth=aws_auth)