Hosting nodejs server at dotcloud

<<<Original poster here →>

Ok I got this to work on Dotcloud. I'm just going to post what you need to know. If you encounter this problem, the final solution will be posted. I want to thank Ken at dotcloud for being on the right track. Thanks to him I found out about environment.yml, environment.json files. Moreover, by doing

console.log(process.env);

      

        
        
        
      

    

there was a HUUGE helper on the server side. Here KK makes a decision:

First, I want you to see how I declare my requirements and variables:

var webSocketServer = require('websocket').server; // websocket
var server = require('http').createServer();
var expr = require("express"); // load the express module
var xpress = expr(); // xpress now holds the server object

      

        
        
        
      

    

Ok, now that you know what this is, I must tell you that I decided to use ejs to create a template. The problem I am facing is that I need my client to be able to "know" on which port to connect to the server via WebSocket. Without a websocket connection already in place, how else am I going to provide the client with a "port" type variable. Keep in mind that the port can change, so I couldn't just hardcode the port like 50234 or something at the end of my ws: // url. The solution was to use "ejs".

ejs is a module (ie "npm install ejs"). I'm not going to explain how to use it. But here is the website I used to find out: http://embeddedjs.com/

Here are some things you need to know: When a client points their browser to your dotcloud url, this is how you send them a file, in my case I changed my .html file to an .ejs file so that I can render it as a template.

xpress.get('/', function(req, res) {
    res.render('game', 
    {
        answer: superCoolPort
    });
});

      

        
        
        
      

    

"game" means that in whatever folder I told the server to look for templates, there should be a file named game.ejs. Notice how I am handling a template named game.ejs with some data. In this case, the data is a local variable in my server.js file called "superCoolPort". This is what this variable is:

var superCoolPort = process.env['DOTCLOUD_WWW_SERVER_PORT'];

      

        
        
        
      

    

Ok now the expression ("xpress" in my case) needs to listen on port 8080.

xpress.listen(8080);

      

        
        
        
      

    

This is NOT the port your WebSocket will try to connect to. This is the port on which your browser tries to connect to the page. But Dotcloud doesn't let you put anything on port 80, so if you put it on 8080, they'll redirect it to 80 for you. This way you don't need to enter url: 8080 in the browser.

Now let me explain how the http server becomes wsServer. Basically you have created an http server and make it listen on a port. Then you connect this http server to your websocket server. See where I declare "server" at the top?

This is the port on which the HTTP server will listen. Note that this means the websocket server will also listen on that port.

var webSocketsServerPort = process.env['PORT_SERVER'] || 4242;
server.listen(webSocketsServerPort, function() {
    console.log((new Date()) + "The http server is listening on port " + webSocketsServerPort);
});

// WebSocket Server
var wsServer = new webSocketServer({
    // WebSocket server is tied to a HTTP server. WebSocket request is just
    // an enhanced HTTP request.
    httpServer: server
});

      

        
        
        
      

    

Before going to the client, I want you to know how I set up my express configurations.

xpress.configure(function() {
     // Sets the directory to look for templates
     xpress.set('views', __dirname + '/public');
     // This line tells Express that we are using the ejs engine to render templates
     xpress.set('view engine', 'ejs');
     xpress.use(expr.static(__dirname + "/public"));
     xpress.set("view options", {layout: false});
});

      

        
        
        
      

    

All of the above has been added to the server.js file.

Ok, I'll go over the template. I used to have a file called game.html. Well, I wanted this to be a template that I could display with some data (the port number that the website has to connect). So first I changed the filename to game.ejs. Then I made some changes like this:

<body onload="init()">

      

        
        
        
      

    

became

<body data-port="<%=answer%>" onload="init()">

      

        
        
        
      

    

See how onload = "init ()"? This means that init will not be called until the page is loaded. This is important because when we want to access a port, you are not guaranteed that it is available unless you are inside init (). I know this because I tried to access it before I defined init () and said the variable is null.

Now, inside init (), you can access the port number like this:

var port = $('body').data('port');

      

        
        
        
      

    

My client.js file can now initialize a website connection like this:

this.connection = new WebSocket('ws://pirate-captainlonate.dotcloud.com:' + this.thePort);

      

        
        
        
      

    

where "this.thePort" is the same as "port" at the top.

I want to make this solution as complete as I can, here is my dotcloud.yml file. Its this one directory above the server.js file:

www:
    type: nodejs
    approot: app
    ports:
        server: tcp
    processes:
        app: node app.js
    config:
        node_version: v0.8.x

db:
    type: mongodb

      

        
        
        
      

    

Here is my package.json file. It's in the same directory as my server.js file (which in my case is called app.js):

{
  "name": "app",
  "version": "0.0.0",
  "scripts": {
    "start" : "node app.js",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "dependencies":{
      "express" : "",
      "mongodb" : "",
      "fs": "",
      "ejs": "",
      "ws": "",
      "websocket": ""
  },
  "repository": "",
  "author": "",
  "license": "BSD"
}

      

        
        
        
      

    

Finally, I honestly don't know if this is needed or not, but here is my supervisord.conf file. It is located in the same directory as server.js.

[program:node]
command = node app.js
directory = /home/dotcloud/current

      

        
        
        
      

    

Okay, I think that's all. I hope I left nothing behind. Ultimately though these changes were necessary for me to have my nodejs application use "websocket" to deploy and run in Dotcloud.