A process in which we can run node apps with different environment settings which are declared in a different file. This helps in scalability and deployment.

node_environment_variables.md

How to run node in an environment aware setting.

1. Create a config folder /config
2. Create an /config/env.json in the config folder which will hold the environmental properties for each environment. example

	{
	    "development": {
	        "port": 3000
	    },
	    "production": {
	        "port": 80
	    }
	}  

3. Create a properties file in the config folder /config/properties.js
4. In the properties file add the following:

	var env = require('./env.json');
	exports.config = function () {
		var node_env = process.env.NODE_ENV || 'development';
		return env[node_env];
	};

4. In the main node file example app.js file, we need to start using the config properties. example usage below.

	var properties = require('./config/properties')
	var config = properties.config();
	var port = config.port;
	app.set('port', process.env.PORT || port);
	
	//we use the environment declared port here.
	http.createServer(app).listen(port, function () {
		console.log('Express server listening on port ' + port);
	});

5. Finally to run node with any of the environment properties, use any of the examples below:

    NODE_ENV=production node app.js
    NODE_ENV=production nodemon app.js
    NODE_ENV=production pm2 start app.js