aws_lambda_sns_to_slack.js

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/XXXX/XXXXX/XXXXXX';
const slack_req_opts = url.parse(slack_url);
const slack_channel = '@user_name'; //or channel name
slack_req_opts.method = 'POST';
slack_req_opts.headers = {'Content-Type': 'application/json'};

exports.handler = function(event, context, callback) {
  (event.Records || []).forEach(function (rec) {
    if (rec.Sns) {
      var req = https.request(slack_req_opts, function (res) {
        if (res.statusCode !== 200) {
          callback('failed to post message, status code: ' + res.statusCode);
        } 
      });
      
      req.on('error', function(e) {
        callback(e);
      });
      
      req.write(JSON.stringify(
          { 
          channel: slack_channel,
          username: 'AWS',
          attachments: [{
              fallback: JSON.stringify(rec.Sns.Subject, null, '  '),
              pretext: rec.Sns.Subject,
              text: rec.Sns.Message
          }]      
          })); 
      
      req.end();
    }
  });
};