barebone code for posting slack messages with AWS Lambda

slack_lambda.py

#!/usr/bin/env python3.7

import os
import json
import logging
from botocore.vendored import requests
import ec2

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


SLACK_WEBHOOK_URL = os.environ.get("slack_webhook_url")
SLACK_CHANNEL = os.environ.get("slack_channel")


def handle_custom_notification(message):
    text = message.get("text", "Error: missing text in the custom notification message")
    channel = message.get("channel", SLACK_CHANNEL)
    username = message.get("username", "Slack lambda")
    icon_emoji = message.get("icon_emoji", ":black_circle:")

    slack_message = dict(
        text=text,
        channel=channel,
        username=username,
        icon_emoji=icon_emoji
    )

    return slack_message


def post_slack_message(message):
    """Makes a http POST request to slack webhook url, posting a notification message.

    Args:
        message (dict): a payload with slack message data

    Returns:
        boolean: message has been sent successfully or not
    """

    response = requests.post(SLACK_WEBHOOK_URL,
                             data=json.dumps(message),
                             headers={'Content-Type': 'application/json'}
                             )

    if response.status_code != 200:
        raise ValueError('Request to slack returned an error: %s, the response is: %s' %
                         (response.status_code, response.text))
    return True


def main(event, context):
    """Main function handler.

    Args:
        event (?):?
        context (?): ?

    Returns:
        boolean: a function invocation succeeded or not
    """

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

    slack_message = handle_custom_notification(message)
    post_slack_message(slack_message)

    return True