See: https://qiita.com/ma2shita/items/8f1b4b12faa99dd17063 | Slack via API Gateway -> this function

max1click-demo_JF2018_response.py

"""
INPUT: API Gateway
required ENVs;
- OUTGOING_TOKEN: Slack's Outgoing Webhook Token

"""

import json
import logging
logger = logging.getLogger()
logger.setLevel(logging.INFO)
import urllib.parse
import os
import boto3

NAME_IDX = {
    'ma2shita': 'max',
    'moto': 'moto',
    'katayama': 'yaman'
}

def lambda_handler(event, context):
    logger.info('Received event: ' + json.dumps(event))    
    b = urllib.parse.parse_qs(event['body'])
    if b['token'][0] != os.environ['OUTGOING_TOKEN']:
        return {
            'statusCode': 403,
            'body': json.dumps('Invalid Token')
        }
    
    shadowDoc = {'state':{'reported':{'status':'running'}}}
    iot = boto3.client('iot-data')
    thingName = NAME_IDX[b['user_name'][0]]
    iot.update_thing_shadow(thingName=thingName, payload=json.dumps(shadowDoc))

    f = boto3.client("lambda")
    f.invoke(
        FunctionName='max1click-demo_JF2018_transiton_to_idle',
        InvocationType='Event',
        Payload=json.dumps({
            'thing_name': thingName,
            'transition_wating_sec': 15
        })
    )
    
    return {"statusCode": 204}