[Lambda] e.g. DatadogMonitor->SNS->Lambda->Slack

convertDistributionId.py

from __future__ import print_function

import boto3
import json
import logging
import os
import re

from base64 import b64decode
from urllib2 import Request, urlopen, URLError, HTTPError


# The base-64 encoded, encrypted key (CiphertextBlob) stored in the kmsEncryptedHookUrl environment variable
ENCRYPTED_HOOK_URL = os.environ['kmsEncryptedHookUrl']
# The Slack channel to send a message to stored in the slackChannel environment variable
SLACK_CHANNEL = os.environ['slackChannel']

HOOK_URL = "https://" + boto3.client('kms').decrypt(CiphertextBlob=b64decode(ENCRYPTED_HOOK_URL))['Plaintext']

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


def lambda_handler(event, context):
    logger.info("Event: " + str(event))
    snstext = event['Records'][0]['Sns']

    subject = snstext['Subject']
    message = snstext['Message']

    result = re.sub(r'\n', "", message)
    result = re.sub(r'^.*distributionid:', "", result)
    distributionid = re.sub(r' was .*$', "", result).upper()
    logger.info("DistributionId: " + distributionid)

    cf = boto3.client('cloudfront')
    response = cf.get_distribution(Id=distributionid)

    distributionconfig = response['Distribution']['DistributionConfig']
    
    try:
        alias = distributionconfig['Aliases']['Items'][0]
    except:
        alias = '-'
    originname = distributionconfig['Origins']['Items'][0]['DomainName']
    post_message = "DistributionId: " + distributionid + "\n"
    post_message = post_message + "CNAME[0]: " + alias + "\n"
    post_message = post_message + "Origin[0]: " + originname + "\n"
    logger.info("Post Message: " + post_message)

    slack_message = {
        'channel': SLACK_CHANNEL,
        'text': "%s\n```\n%s```" % (subject, post_message)
    }

    req = Request(HOOK_URL, json.dumps(slack_message))
    try:
        response = urlopen(req)
        response.read()
        logger.info("Message posted to %s", slack_message['channel'])
    except HTTPError as e:
        logger.error("Request failed: %d %s", e.code, e.reason)
    except URLError as e:
        logger.error("Server connection failed: %s", e.reason)