lambda.py

import urllib
import json

def lambda_handler(event, context):
    json_text = json.dumps({
        "text": "Tea is ready at Corestom", 
        "icon_url": "https://emoji.slack-edge.com/T026J8X3T/corestum/30c38516350c8fc6.png",
        "username": "Corestom Teabot"
    })
    params = urllib.urlencode({'payload': json_text})
    f = urllib.urlopen("<insert hook URL here>", params)
    print f.read()