Pass configuration to controller - node.js

Question

I am building a node.js app that will upload files to my S3 bucket using knox. I am able to interact with S3 as expected, but I would like to make my controller to receive configuration so I can dynamically construct my client with configuration values.
My questions is how do I get configuration paramters down the call stack to my controller without being careless?
Disclaimer: I am rather new to Node.js so it could be simply my lack of knowledge in the difference between exports. and module.exports.*
Here is an example of how the interaction works with my code:
app.js
...
config = require('./config/config')['env'];
require('./config/router')(app, config);
...
router.js
module.exports = function(app, config) {
...
var controller = require('../app/controllers/home'); //Is there a way for me to pass config here?
app.post('/upload', controller.upload); //Or here?
...
}
home.js
var knox = require('knox');
var client = knox.createClient({ ... }); //I want to use config.key, config.secret, etc instead of hard-coded values
...
exports.upload = function(req, res) {
//Use client
}
...

Answer 1

Try doing something like this...
var config = require('./config/config')['env'];
// The use function will be called before your
// action, because it is registered first.
app.use(function (req, res, next) {
// Assign the config to the req object
req.config = config;
// Call the next function in the pipeline (your controller actions).
return next();
});
// After app.use you register your controller action
app.post('/upload', controller.upload);
And then in your controller action...
exports.upload = function(req, res) {
//Your config should be here...
console.log(req.config);
}
Ps. I can not try it right now, but I solved a similar issue like this.

Answer 2

You can pass the configuration in as a parameter to you controller
Controller
// controller.js file
module.exports = function(req, res, config) {
console.log('config parameter passed to controller', config);
res.end('config passed')
}
App
// index.js file with the express app
var controller = require('./controller');
var config = {
key1: 'foo'
};
var express = require('express');
var app = express();
var port = 3000;
app.get('/', function(req, res){
controller(req, res, config);
});
app.listen(port);
console.log('app listening on port', 3000);
Demo
You can check out the github repo for a complete example

Answer 3

Alternative approach if you want to call multiple functions from one single route, this will do it.
Route
var users = require('../controllers/users');
app.route('/login').post(function(req, res){
if(users.authenticate()){
console.log('valid user');
if(users.createUser())
{
console.log('user created');
}
}
});
Controller
exports.authenticate = function(req, res, next) {
return true;
};
exports.createUser = function(req, res, next) {
return true;
};