how to setup Winston logger by nconf

setupLogger.js

/**
 * Setup multiple winston logger:
 * https://github.com/flatiron/winston#working-with-multiple-loggers-in-winston
 * 
 * by nconf:
 * https://github.com/flatiron/nconf
 */
 
var winston = require('winston'),
    nconf = require('nconf');


var config = nconf.argv()
    .env()
    .file({ file: 'scripts/config/local_settings.json' })
    .file({ file: 'scripts/config/global_settings.json' });

var loggerConfig = config.get('logger');
Object.keys(loggerConfig).forEach(function(key) {
    winston.loggers.add(key, loggerConfig[key]);
});

/**
 * global_settings.json
 */
 
{
    "logger": {
        "db": {
            "console": {
                "level": "info",
                "colorize": true,
                "label": "db"
            }
        },
        "express": {
            "console": {
                "level": "info",
                "colorize": true,
                "label": "express"
            }
        },
        "passport": {
            "console": {
                "level": "info",
                "colorize": "true",
                "label": "passport"
            }
        }
    }
}

/**
 * usage
 */
 
 var logger = require('winston').loggers.get('express');
 logger.info('hello world!');