AWS Lambda function for forwarding SNS notifications to Slack

sns-to-slack.js

// Added by Ben Yanke
// from https://gist.github.com/benyanke/862e446e5a816551928d8acc2d98b752
console.log('Loading function');

const https = require('https');
const url = require('url');

// SETUP
// urlToUse = in this environment variable, place the name of another environment variable which contains the key. 
// This allows easy dev/prod switching.

// For example:
// urlToUse = 'devkey'
// devkey = 123456
// prodkey = 654321
// Easily switch between dev and prod by changing urlToUse.


// 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/" + process.env[process.env.urlToUse]

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);
            });



            const has = Object.prototype.hasOwnProperty; // cache the lookup once, in module scope.

            try {
                // var msg = JSON.parse(rec.Sns.Message);
                var msg = rec.Sns.Message;
                console.log(msg);
            } catch (err) {
                console.log(err)
            }


            // If event is a CodeDeploy event
            if (has.call(msg, "deploymentId")) {
                deploymentOverview = JSON.parse(msg.deploymentOverview);


                // Check state
                if (deploymentOverview.Message.Failed > 0 || msg.status == 'FAILED') {
                    color = "danger";
                } else {
                    color = "good";
                }

                // Output error msg if it exists
                if (has.call(msg, "errorInformation")) {
                    errorInformation = JSON.parse(msg.errorInformation);
                    textMsg = errorInformation.ErrorMessage;
                } else {
                    textMsg = "Message not set";
                }

                // Send to slack

                req.write(JSON.stringify({
                    "attachments": [{
                        "fallback": "CodeDeploy: " + cloudWatchMessage.AlarmName + " was triggered in " + cloudWatchMessage.Region,
                        "pretext": "CodeDeploy",
                        "title": "CodeDeploy: Status Updated to '" + msg.status + "' for deployment " + msg.deploymentId,
                        "title_link": 'TITLE LINK',
                        "text": textMsg,
                        "color": color,
                        "author_name": "Application: " + msg.applicationName,
                        "author_link": 'LINK',
                        "fields": [{
                                "title": "Instances Succeeded",
                                "value": deploymentOverview.Succeeded,
                                "short": true
                            },
                            {
                                "title": "Instances Failed",
                                "value": deploymentOverview.Failed,
                                "short": true
                            },
                            {
                                "title": "Instances Skipped",
                                "value": deploymentOverview.Skipped,
                                "short": true
                            },
                            {
                                "title": "Instances In Progress",
                                "value": deploymentOverview.InProgress,
                                "short": true
                            },
                            {
                                "title": "Instances Pending",
                                "value": deploymentOverview.Pending,
                                "short": true
                            }

                        ]
                    }]
                }))

            }

            // If event is a CloudWatch event
            else if (rec.Sns.Subject.startsWith("ALARM:") || rec.Sns.Subject.startsWith("OK:")) {

                cloudWatchMessage = JSON.parse(rec.Sns.Message)

                linkToInstance = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/ec2/v2/home?region=" +
                    cloudWatchMessage.Region.toLowerCase() + "#Instances:" +
                    cloudWatchMessage.Trigger.Dimensions[0].name +
                    "=" + cloudWatchMessage.Trigger.Dimensions[0].value +
                    ";sort=tag:Name";

                linkToAllInstances = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/ec2/v2/home?region=" +
                    cloudWatchMessage.Region.toLowerCase() + "#Instances:sort=tag:Name";

                linkToVpnConnections = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/vpc/home?region=" +
                    cloudWatchMessage.Region.toLowerCase() + "#VpnConnections";

                linkToConsole = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/console/home?region=" +
                    cloudWatchMessage.Region.toLowerCase();

                // Handle different types of errors

                // EC2
                if (cloudWatchMessage.Trigger.Namespace == "AWS/EC2") {
                    consoleLink = "<" + linkToInstance + "|Click here to open affected EC2 instance>";

                    // VPN
                } else if (cloudWatchMessage.Trigger.Namespace == "AWS/VPN") {
                    consoleLink = "<" + linkToVpnConnections + "|Click here to open VPN connections>";

                    // All others
                } else {
                    consoleLink = "<" + linkToConsole + "|Click here to open AWS console>";
                }

                if (rec.Sns.Subject.startsWith("OK:")) {
                    var color = "good";
                    var type = "Alarm resolved";
                } else {
                    var color = "danger"
                    var type = "ALARM TRIGGERED";
                }

                req.write(JSON.stringify({
                    "attachments": [{
                        "fallback": "CloudWatch " + type + ": " + cloudWatchMessage.AlarmName + " in " + cloudWatchMessage.Region,
                        "pretext": "New CloudWatch Alert",
                        "title": "CloudWatch Alarm: " + cloudWatchMessage.AlarmName,
                        "title_link": linkToAllInstances,
                        "text": cloudWatchMessage.NewStateReason,
                        "color": color,
                        "author_name": "Service: " + cloudWatchMessage.Trigger.Namespace,
                        "author_link": linkToAllInstances,
                        "fields": [{
                                "title": "Alarm",
                                "value": cloudWatchMessage.AlarmName,
                                "short": true
                            },
                            {
                                "title": "Alarm Description",
                                "value": cloudWatchMessage.AlarmDescription,
                                "short": true
                            },
                            {
                                "title": "Alarm Status",
                                "value": type,
                                "short": true
                            },
                            {
                                "title": "Region",
                                "value": cloudWatchMessage.Region,
                                "short": true
                            },
                            {
                                "title": "Environment",
                                "value": cloudWatchMessage.Trigger.Namespace,
                                "short": true
                            },
                            {
                                "title": "AWS Console",
                                "value": consoleLink,
                                "short": true
                            }

                        ]
                    }]
                }))

            }

            // If event is an autoscale Event
            else if (rec.Sns.Subject.startsWith("Auto Scaling: launch")) {

                cloudWatchMessage = JSON.parse(rec.Sns.Message)

                linkToInstance = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/ec2/v2/home?region=" +
                    cloudWatchMessage.Region.toLowerCase() + "#Instances:" +
                    cloudWatchMessage.Trigger.Dimensions[0].name +
                    "=" + cloudWatchMessage.Trigger.Dimensions[0].value +
                    ";sort=tag:Name";

                linkToAllInstances = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/ec2/v2/home?region=" +
                    cloudWatchMessage.Region.toLowerCase() + "#Instances:sort=tag:Name";

                linkToVpnConnections = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/vpc/home?region=" +
                    cloudWatchMessage.Region.toLowerCase() + "#VpnConnections";

                linkToConsole = "https://" + cloudWatchMessage.Region.toLowerCase() +
                    ".console.aws.amazon.com/console/home?region=" +
                    cloudWatchMessage.Region.toLowerCase();

                // Handle different types of errors

                // EC2
                if (cloudWatchMessage.Trigger.Namespace == "AWS/EC2") {
                    consoleLink = "<" + linkToInstance + "|Click here to open affected EC2 instance>";

                    // VPN
                } else if (cloudWatchMessage.Trigger.Namespace == "AWS/VPN") {
                    consoleLink = "<" + linkToVpnConnections + "|Click here to open VPN connections>";

                    // All others
                } else {
                    consoleLink = "<" + linkToConsole + "|Click here to open AWS console>";
                }


                req.write(JSON.stringify({
                    "attachments": [{
                        "fallback": "Scaling Alert: " + cloudWatchMessage.AlarmName + " was triggered in " + cloudWatchMessage.Details,
                        "pretext": "New AutoScaling Alert",
                        "title": "AutoScaling Up: " + cloudWatchMessage.Service,
                        "title_link": linkToAllInstances,
                        "text": cloudWatchMessage.NewStateReason,
                        "color": "danger",
                        "author_name": "Service: " + cloudWatchMessage.Trigger.Namespace,
                        "author_link": linkToAllInstances,
                        "fields": [{
                                "title": "Alarm",
                                "value": cloudWatchMessage.AlarmName,
                                "short": true
                            },
                            {
                                "title": "Alarm Description",
                                "value": cloudWatchMessage.AlarmDescription,
                                "short": true
                            },
                            {
                                "title": "Region",
                                "value": cloudWatchMessage.Region,
                                "short": true
                            },
                            {
                                "title": "Environment",
                                "value": cloudWatchMessage.Trigger.Namespace,
                                "short": true
                            },
                            {
                                "title": "AWS Console",
                                "value": consoleLink,
                                "short": true
                            }

                        ]
                    }]
                }))

            }

            // If event is an RDS Event
            else if (rec.Sns.Subject.startsWith("RDS")) {

                message = JSON.parse(rec.Sns.Message)

                var messagesToIgnore = ["Finished DB Instance backup", "Backing up DB instance"]
                var eventMsg = message['Event Message'];

                // Ignore certain types of message
                if (messagesToIgnore.includes(eventMsg)) {
                    console.log("Event message was " + eventMsg + " - ignoring and not sending notification to slack");
                    return;
                }

                req.write(JSON.stringify({
                    text: "RDS Notification: \n      DB '" + message['Source ID'] + "' : " + eventMsg
                }))

            }

            // Otherwise, if not a CloudWatch event, send full alert subject and message
            else {

                req.write(JSON.stringify({
                    text: "*Subject:*   " + rec.Sns.Subject + "\n *Message:* " + rec.Sns.Message
                }))

            }

            req.end();
        }
    });
};