AWS CloudFormation Custom Resource - Spot (Part 1 - lambda creator)

AWS CF Custom Spot lambda - part 1

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

AWS.config.apiVersions = {
    ec2: '2015-10-01'
};

exports.handler = function(event, context) {
    var ec2 = new AWS.EC2({ region: event.ResourceProperties.Region });
    if (event.RequestType === 'Delete') {
        ec2.terminateInstances({ InstanceIds: [ event.PhysicalResourceId ] }, function(err, data) {
            if (err) context.fail(err);
            else {
                sendResponse(event, function(err){
                    if (err) context.fail(err);
                    else context.done();
                });
            }
        });
    } else if(event.RequestType === 'Create') {
        // create spot request
        ec2.requestSpotInstances(event.ResourceProperties.params, function(err, data) {
            if (err) context.fail(err);
            else {
                var parsedUrl = url.parse(event.ResponseURL);
                // store ResponseURL as tag for spot request
                var _params = {
                    Resources: [ data.SpotInstanceRequests[0].SpotInstanceRequestId ],
                    Tags: [ 
                        { Key: 'cf_hostname', Value: parsedUrl.hostname },
                        { Key: 'cf_access', Value: parsedUrl.query },
                        { Key: 'cf_stack', Value: event.StackId },
                        { Key: 'cf_request', Value: event.RequestId },
                        { Key: 'cf_resource', Value: event.LogicalResourceId }
                    ]
                };
                ec2.createTags(_params, function(err, data) {
                    if (err) context.fail(err);
                    else context.done();
                });
            }
        });
    } else { // assume Update
        context.done();
    }
};

// Sends a response to the pre-signed S3 URL
var sendResponse = function(event, callback) {
    var _body = JSON.stringify({
        Status: 'SUCCESS',
        StackId: event.StackId,
        RequestId: event.RequestId,
        LogicalResourceId: event.LogicalResourceId,
        PhysicalResourceId: event.PhysicalResourceId
    });

    var parsedUrl = url.parse(event.ResponseURL);
    var options = {
        hostname: parsedUrl.hostname,
        port: 443,
        path: parsedUrl.path,
        method: 'PUT',
        headers: {
            'Content-Type': '',
            'Content-Length': _body.length
        }
    };

    var req = https.request(options, function(res) {
        console.log('STATUS:', res.statusCode);
        callback(null);
    });

    req.on('error', function(err) {
        callback(err);
    });

    req.write(_body);
    req.end();
};