How to cache an AWS S3 file on a node.js server and serve it on request?

For my website, I am deploying all the assets (fonts/images/js etc) to an S3 bucket. The index.html (a single-page Ember.js application), is deployed on an elastic beanstalk node.js server. The node app.js takes any request to www.domain.com/* and serves the locally stored index.html. I would like to be able to cut out the process of deploying a new application to elastic beanstalk for every production build and simply deploy all assets and the index.html to the S3 bucket.

This is what I have so far:

var AWS = require('aws-sdk'),
    fs = require('fs');
/*
 * AWS Security credentials
 */
AWS.config.loadFromPath('./config.json');

var port = process.env.PORT || 3000,
    http = require("http");

var static = require('node-static');


/*
* Create a node-static server instance
* to serve the './public' folder
*/
var file = new static.Server();

/*
 * Fetch .index.html from S3
 * and cache it locally
 */
var s3 = new AWS.S3();
var params = {Bucket: 'assets', Key: 'index.html'};
var file = fs.createWriteStream('index.html');

s3.getObject(params).
    on('httpData', function(chunk) { file.write(chunk); }).
    on('httpDone', function() { file.end(); }).
    send();

var server = http.createServer(function (request, response) {
    request.addListener('end', function () {
        file.serveFile('index.html', 200, {}, request, response);
    }).resume();
}).listen(port);

This I assume will only get the index.html from S3 when the server first fires up. What would be the best practice for caching, preferably with a 1 minute expiry.

Thanks!