AWS Lambda function for forwarding SNS notifications to Slack

function.js

console.log('Loading function');

const https = require('https');
const url = require('url');
// to get the slack hook url, go into slack admin and create a new "Incoming Webhook" integration
const slack_url = 'https://hooks.slack.com/services/...';
const slack_req_opts = url.parse(slack_url);
slack_req_opts.method = 'POST';
slack_req_opts.headers = {'Content-Type': 'application/json'};

exports.handler = function(event, context) {
  (event.Records || []).forEach(function (rec) {
    if (rec.Sns) {
      var req = https.request(slack_req_opts, function (res) {
        if (res.statusCode === 200) {
          context.succeed('posted to slack');
        } else {
          context.fail('status code: ' + res.statusCode);
        }
      });
      
      req.on('error', function(e) {
        console.log('problem with request: ' + e.message);
        context.fail(e.message);
      });
      
      req.write(JSON.stringify({text: JSON.stringify(rec.Sns.Message, null, '  ')})); // for testing: , channel: '@vadim'
      
      req.end();
    }
  });
};

Not sure if you'd find it useful, but I modified this to show more information about CloudWatch alerts pushed via SNS: It parses the message JSON to see if it's a cloudwatch alert, and if so, it uses slack's attachment formatting.

Non-CloudWatch messages are still just displayed normally.

@benyanke good fork! I also change it for CodeCommit, might fork it to show the code as well later

for those that need a nice icon to their Slack channel, here's the new one for AWS, and crops as a square nicely in Slack Incoming Hooks settings

another trick is to use environment variables so you can actually add your slack channel in the function variables so you can use the script in another function to dump to another channels without change the code itself, like

const slack_url = process.env.SLACK_WEBHOOK_URL || 'https://hooks.slack.com/services/default/link';

and set up as:

Works! Just what I needed, thank you! 😄

How to add 2 slack urls?

How do I update "rec.Sns.Message" to be some custom text? Can I set "rec.Sns.Message" from somewhere in the AWS dashboard?

Newbie here - Can someone explain in little more detail on how to add this into a Lambda? I created a Lambda function, chose its runtime to be Nodejs 10.x and it opens with a default file of index.js. I assume I can not copy and paste this code into the index.js? Anything else special needed to call this from SNS?