Node.js Winston logging

Question

In my node app I am using "Winston" Logging to print the errors in a separate file.

I followed this tutorial.

When I tried to access the logger from other files....

My code:

var winston = require('winston');
var fs = require('fs');

fs.mkdir('./logs', function(err) {
    if (err) throw err;
});

// Define levels to be like log4j in java
var customLevels = {
  levels: {
    debug: 0,
    info: 1,
    warn: 2,
    error: 3
  },
  colors: {
    debug: 'blue',
    info: 'green',
    warn: 'yellow',
    error: 'red'
  }
};

// create the main logger
var logger = new(winston.Logger)({
    level: 'debug',
    levels: customLevels.levels,
    transports: [
        // setup console logging
        new(winston.transports.Console)({
            level: 'info', // Only write logs of info level or higher
            levels: customLevels.levels,
            colorize: true
        }),
        // setup logging to file
        new(winston.transports.File)({
            filename: './logs/project-debug.log',
            maxsize: 1024 * 1024 * 10, // 10MB
            level: 'debug',
            levels: customLevels.levels
        })
    ]
});

// create the data logger - I only log specific app output data here
var datalogger = new (winston.Logger) ({
    level: 'info',
    transports: [
        new (winston.transports.File) ({
            filename: './logs/project-data.log',
            maxsize: 1024 * 1024 * 10 // 10MB
        })
    ]
});

// make winston aware of your awesome colour choices
winston.addColors(customLevels.colors);

var Logging = function() {
    var loggers = {};

    // always return the singleton instance, if it has been initialised once already.
    if (Logging.prototype._singletonInstance) {
        return Logging.prototype._singletonInstance;
    }

    this.getLogger = function(name) {
        return loggers[name];
    }

    Logging.prototype.get = this.getLogger;

    loggers['project-debug.log'] = logger;
    loggers['project-data.log'] = datalogger;

    Logging.prototype._singletonInstance = this;
};

new Logging(); // I decided to force instantiation of the singleton logger here

logger.info('Logging set up OK!');

module.exports = Logging;

Error is throwing:

Logging() is undefined.

Answer 1

The tutorial seems to have a bunch of errors. I got it working by calling

var logger = logging.Logging().get('project-debug.log');

Notice the .log in the argument. The argument has to match one of the names defined in the loggers array.

Answer 2

I spent hours on this, here is my solution: Do not create a new Logger, just change the default one.

Create a module lib/logger.js:

var logger = require('winston');
logger.setLevels({debug:0,info: 1,silly:2,warn: 3,error:4,});
logger.addColors({debug: 'green',info:  'cyan',silly: 'magenta',warn:  'yellow',error: 'red'});
logger.remove(logger.transports.Console);
logger.add(logger.transports.Console, { level: 'debug', colorize:true });
module.exports = logger;

Use in app.js:

var logger = require('./lib/log.js');  

Use from all other modules:

var logger = require('winston');        

Answer 3

The file I have created and explaind:

var winston = require('winston'),
    winstonRedis = require('winston-redis').Redis;

// TR: console'da sadece hepsi tutuluyor olacak çünkü info log seviyesinden sonra diğer tüm log seviyeleri sıralanmış
// EN: all log level will be shown in Console, because 'info' is on the top of list with 0 value.
var transportConsole = new winston.transports.Console({ json: false, timestamp: true, prettyPrint:true, colorize: true, level:'info' }),

// TR: File'da sadece i ve db tutuluyor olacak çünkü i den sonra db log seviyesi sıralanmış
// EN: 'i' and 'db' log levels will be shown in File, because db is after i and for File transport level is 'i'
transportFileDebug = new winston.transports.File({ filename: __dirname + '/debug.log', json: true }),
transportFileException = new winston.transports.File({ filename: __dirname + '/exceptions.log', json: false }),

// TR: rediste sadece db tutuluyor olacak çünkü db den sonra bir log seviyesi yok
// EN: only 'db' will be stored in rediste because 'db' is the last one 
transportRedis = new (winstonRedis)({host: '127.0.0.1', port: 6379, level:'db'});


var logger = new (winston.Logger)({
    levels: {
        info: 0,
        warn: 1,
        error: 2,
        verbose: 3,
        i: 4,
        db: 5
    },
    transports: [
        transportConsole,
        transportFileDebug,
        transportRedis
    ],
    exceptionHandlers: [
        transportConsole,
        transportFileException
    ],
    exitOnError: false
});

winston.addColors({
    info: 'green',
    warn: 'cyan',
    error: 'red',
    verbose: 'blue',
    i: 'gray',
    db: 'magenta'
});

logger.i('iiiii foobar level-ed message');
logger.db('dbbbbb foobar level-ed message');
logger.info('infoo foobar level-ed message');
logger.warn('warnnnn foobar level-ed message');
logger.error('errroor foobar level-ed message');

module.exports = logger;

Answer 4

I have used winston debug logging but it's not that effective. I faced similar problems as well as it crashed sometimes. I recently switched to an new module used by mopublish team. It's wonderful also support http logging via morgan. NPM module elogger - https://github.com/techunits/elogger