AWS CloudWatch slack python script

'''

Follow these steps to configure the webhook in Slack:

  1. Navigate to https://<your-team-domain>.slack.com/services/new

  2. Search for and select "Incoming WebHooks".

  3. Choose the default channel where messages will be sent and click "Add Incoming WebHooks Integration".

  4. Copy the webhook URL from the setup instructions and use it in the next section.

To encrypt your secrets use the following steps:

  1. Create or use an existing KMS Key - http://docs.aws.amazon.com/kms/latest/developerguide/create-keys.html

  2. Click the "Enable Encryption Helpers" checkbox

  3. Paste <SLACK_CHANNEL> into the slackChannel environment variable

  Note: The Slack channel does not contain private info, so do NOT click encrypt

  4. Paste <SLACK_HOOK_URL> into the kmsEncryptedHookUrl environment variable and click encrypt

  Note: You must exclude the protocol from the URL (e.g. "hooks.slack.com/services/abc123").

  5. Give your function's role permission for the kms:Decrypt action.

     Example:

{

    "Version": "2012-10-17",

    "Statement": [

        {

            "Sid": "Stmt1443036478000",

            "Effect": "Allow",

            "Action": [

                "kms:Decrypt"

            ],

            "Resource": [

                "<your KMS key ARN>"

            ]

        }

    ]

}

'''

from __future__ import print_function

import boto3

import json

import logging

import os

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))

    message = json.loads(event['Records'][0]['Sns']['Message'])

    # logger.info("Message: " + str(message))

    alarm_name = message['AlarmName']

    #old_state = message['OldStateValue']

    new_state = message['NewStateValue']

    reason = message['NewStateReason']

    color = '#00e200'

    username = 'AWS-CloudWatch'

    

    if new_state == 'ALARM':

        color = '#ff0000'

    slack_message = {

        'channel': SLACK_CHANNEL,

        'username': username,

        'pretext': "[AWS - %s] : state - %s" % (alarm_name, new_state),

        'color': color,

        'text': "%s state is now %s: %s" % (alarm_name, new_state, reason)

    }

    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)