AWS Lambda Post To Slack Channel from DynamoDB

slack_postback_lambda.js

var AWS = require('aws-sdk');
var path = require('path');
var https = require('https');

/**
 * This assumes that messages are added to DynamoDB
 * with parameters `name` and `message`. 
 *
 * To get this to work with your slack channel, you 
 * first need to configure Incoming Webhook for your 
 * Slack organization. 
 * 
 * See the Bonus Activity from [Lab 4 from the AWS Lambda Zombie Workshop](https://github.com/awslabs/aws-lambda-zombie-workshop/blob/master/README.md#lab-4---slack-integration)
 * for the context.
 **/
exports.handler = function(event, context) { 
    console.log(JSON.stringify(event, null, '  '));
    event.Records.forEach(function(record) {
        if (typeof record.dynamodb.NewImage != 'undefined') {
            postToSlack(
                record.dynamodb.NewImage.name.S,
                record.dynamodb.NewImage.message.S,
                function (status) { 
                    context.done(null, status);
                }
            );
        } else {
            console.log('skipping non-inserts');
        }
    });
};

function postToSlack(from, body, completedCallback) {
    
    var message = {
        username: from, 
        text: body,
        icon_emoji: ":ghost:"
    };
    
    var messageString = JSON.stringify(message);
    console.log("message sent to slack: ", messageString);
    
    // Options and headers for the HTTP request   
    var options = {
        host: 'hooks.slack.com',
        port: 443,
        path: '/services/POST/YOUR/SERVICES_URL',
        method: 'POST',
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
            'Content-Length': Buffer.byteLength(messageString)
        }
    };
    
    // Setup the HTTP request
    var req = https.request(options, function (res) {

        res.setEncoding('utf-8');
              
        // Collect response data as it comes back.
        var responseString = '';
        res.on('data', function (data) {
            responseString += data;
        });
        
        // Log the responce received from Slack.
        // Or could use JSON.parse(responseString) here to get at individual properties.
        res.on('end', function () {
            console.log('Slack Response: ' + responseString);
            completedCallback('API request sent successfully.');
        });
    });
    
    // Handler for HTTP request errors.
    req.on('error', function (e) {
        console.error('HTTP error: ' + e.message);
        completedCallback('API request completed with error(s).');
    });
    
    // Send the HTTP request to the Slack API.
    // Log the message we are sending to Slack.
    console.log('Slack API call: ' + messageString);
    req.write(messageString);
    req.end();
}