Logger.js

var winston = require('winston'),
    fs = require('fs'),
    logDir = 'log', // Or read from a configuration
    env = process.env.NODE_ENV || 'development',
    logger;

var Logentries = require('winston-logentries');

winston.setLevels(winston.config.npm.levels);
winston.addColors(winston.config.npm.colors);

if (!fs.existsSync(logDir))
{
    // Create the directory if it does not exist
    fs.mkdirSync(logDir);
}

logger = new(winston.Logger)(
{
    transports: [
        new winston.transports.Console(
        {
            level: 'debug',
            colorize: true,
            prettyPrint: true
        }),
        new winston.transports.Logentries(
        {
            level: 'debug',
            handleExceptions: true,
            colorize: true,
            token: process.env.LOGENTRIES_TOKEN
        }),
        new winston.transports.File(
        {
            level: env === 'development' ? 'debug' : 'info',
            filename: logDir + '/logs.json',
            json: true,
            handleExceptions: true,
            maxsize: 1024 * 1024 * 10 // 10MB,
        })
    ],
    exceptionHandlers: [
        new winston.transports.File(
        {
            json: true,
            filename: 'log/exceptions.json'
        })
    ]
});

process.on('uncaughtException', function (err)
{
    logger.error('uncaughtException',
    {
        message: err.message,
        stack: err.stack
    });
    process.exit(1);
});

module.exports = logger;

// Use this singleton instance of logger like:
// logger = require( 'logHandler.js' );
// logger.debug( 'your debug statement' );
// logger.warn( 'your warning' );