Lambda script to notify cloudformation events to slack through SNS

aws_lambda_cloudformation_slack.js

// Adaptation from https://medium.com/cohealo-engineering/how-set-up-a-slack-channel-to-be-an-aws-sns-subscriber-63b4d57ad3ea
var https = require('https');
var util = require('util');

exports.handler = function(event, context) {
    console.log(JSON.stringify(event, null, 2));
    console.log('From SNS:', event.Records[0].Sns.Message);

    var postData = {
        "channel": "#aws_playground",
        "username": "AWS",
        "text": "*" + event.Records[0].Sns.Subject + "*",
        "icon_emoji": ":aws:"
    };

    var message = event.Records[0].Sns.Message;
    var splitMessage=message.split("\n");

    var severity = "good";

    var filterKeywords = [
        "LogicalResourceId",
        "ResourceStatus",
        "ResourceStatusReason",
        "Timestamp",
        "ResourceProperties"];

    var dangerMessages = [
        "ROLLBACK_IN_PROGRESS",
        "ROLLBACK_COMPLETE",
        " but with errors",
        " to RED",
        "During an aborted deployment",
        "Failed to deploy application",
        "Failed to deploy configuration",
        "has a dependent object",
        "is not authorized to perform",
        "Pending to Degraded",
        "Stack deletion failed",
        "Unsuccessful command execution",
        "You do not have permission",
        "Your quota allows for 0 more running instance"];

    var warningMessages = [
        "DELETE_IN_PROGRESS",
        "DELETE_COMPLETE",
        " aborted operation.",
        " to YELLOW",
        "Adding instance ",
        "Degraded to Info",
        "Deleting SNS topic",
        "is currently running under desired capacity",
        "Ok to Info",
        "Ok to Warning",
        "Pending Initialization",
        "Removed instance ",
        "Rollback of environment"        
        ];

    message = ""
    for(var filterKeywordsItem in filterKeywords) {
        for (var i = 0; i < splitMessage.length; i++) {
            if (splitMessage[i].indexOf(filterKeywords[filterKeywordsItem]) != -1) {
                message += (splitMessage[i] + "\n")
            }
        }
    }
    
    for(var dangerMessagesItem in dangerMessages) {
        if (message.indexOf(dangerMessages[dangerMessagesItem]) != -1) {
            severity = "danger";
            break;
        }
    }
    
    // Only check for warning messages if necessary
    if (severity == "good") {
        for(var warningMessagesItem in warningMessages) {
            if (message.indexOf(warningMessages[warningMessagesItem]) != -1) {
                severity = "warning";
                break;
            }
        }        
    }

    postData.attachments = [
        {
            "color": severity, 
            "text": message
        }
    ];

    var options = {
        method: 'POST',
        hostname: 'hooks.slack.com',
        port: 443,
        path: '/services/*******'
    };

    var req = https.request(options, function(res) {
      res.setEncoding('utf8');
      res.on('data', function (chunk) {
        context.done(null);
      });
    });
    
    req.on('error', function(e) {
      console.log('problem with request: ' + e.message);
    });    

    req.write(util.format("%j", postData));
    req.end();
};