HetrixTools - Make Twilio calls through webhooks with AWS Lambda

lambda_function.py

#
# This microservice links HetrixTools and Twilio together through webhooks.
# If HetrixTools detects downtime, this microservice is called, which calls your phone/SIP number
# and announces which monitor detected an issue using TTS.
#
# GET Parameters:
# - token = Must match SecretKey
# - repeat = How many times should the message be repeated (optional, default 2)
# - to = Which number / SIP destination to call
#
# Environment variables:
# - ApplicationSid = Twilio ApplicationSid
# - TwilioAuthToken = self explanatory
# - SecretKey = An auth token, see the get parameter "token"
# - From = A Twilio verified phone number, alternatively an arbitrary string if calling SIP
#
# Runtime: Python2.7.
# Have to manually install requests, Lambda doesn't support it by default
# `pip install requests -t .` and then upload the whole directory (including lambda_function.py)
# to Lambda in a ZIP.


import json
import logging
import os
import requests
from requests.auth import HTTPBasicAuth

secret_key = os.environ['SecretKey']

logger = logging.getLogger()
logger.setLevel(logging.INFO)

def respond(err, res=None):
    return {
        'statusCode': '400' if err else '200',
        'body': err.message if err else json.dumps(res),
        'headers': {
            'Content-Type': 'application/json',
        },
    }


def lambda_handler(event, context):
    decoded = json.loads(event['body'])

    if(secret_key != event['queryStringParameters']['token']):
        return respond("Invalid token")

    if 'repeat' not in event['queryStringParameters']:
        repeats = 2
    else:
        repeats = int(event['queryStringParameters']['repeat'])

    # TTS response
    msg = '<Response><Say voice="alice">'
    msg += 'Hello Administrator, a downtime event has been detected......'
    for i in range(0, repeats):
        msg += 'Warning.....'
        msg += 'Monitor %s is OFFLINE...' % decoded['monitor_name']
        msg += '...'
    
    msg += 'Hope you have a wonderful day.'
    msg += '</Say></Response>'

    data = {
        'To': event['queryStringParameters']['to'],
        'From': os.environ['From'],
        'Twiml': msg
    }

    
    auth = HTTPBasicAuth(os.environ['ApplicationSid'], os.environ['TwilioAuthToken'])
    response = requests.post('https://api.twilio.com/2010-04-01/Accounts/%s/Calls.json' % os.environ['ApplicationSid'], data=data, auth=auth)
    
    print(response)

    return respond(None, "OK")