Node Winston instantiate each instance with a name

Question

This is my winston logger class:

const winston = require('winston');
const config = require('../config');
const env = process.env;

winston.setLevels({
    debug:0,
    info: 1,
    silly:2,
    warn: 3,
    error:4,
});

winston.addColors({
    debug: 'green',
    info:  'cyan',
    silly: 'magenta',
    warn:  'yellow',
    error: 'red'
});

let transports = [];
transports.push(new (winston.transports.File)({filename: config.logger.fileName}));
if (env.CONSOLE == 'true' || config.logger.consoleLog) {
    transports.push(new (winston.transports.Console)({colorize:true}));
}

winston.configure({
    transports: transports
});

if (config.logger.debug || env.DEBUG == 'true') {
    winston.level = 'debug';
}


module.exports = winston;

I use this like so:

const logger = require('src/logger');
logger.info("Hello there");

The problem is all files would then append to the same file without any distinction; I want to be able to set the "name" so that in my log, I see something like "[Name1] ..." "[Name2] ..." etc.

How do I accomplish this?

Answer 1

Winston has a concept of 'categories'. But there is no easy way to put the category name into a log message.

Here is a workaround that leverages 'label' property to achieve this:

'use strict';

const winston = require('winston');

winston.setLevels({
	debug: 0,
	info: 1,
	silly: 2,
	warn: 3,
	error: 4,
});

winston.addColors({
	debug: 'green',
	info: 'cyan',
	silly: 'magenta',
	warn: 'yellow',
	error: 'red'
});

const getLogger = function (category) {
	//If we call .get it'll create a default logger
	//We don't need a default one, we want to configure the
	//transports/labels, so we check if it exists
	//and return only if it's configured properly
	if (winston.loggers[category]) {
		return winston.loggers.get(category);
	}

	//Apply your logic to identify log level here.
	let level = 'silly';

	//Set up the transports you need (omit console if needed)
	let transports = [
		new (winston.transports.File)({
			filename: './logs.txt',
			//Notice this 'label' property
			label: category,
			level
		}),
		new (winston.transports.Console)({
			colorize: true,
			label: category,
			level
		})
	];

	return winston.loggers.add(category, {transports});
};

module.exports = {getLogger};

const generalLogger = getLogger('general');
const appleLogger = getLogger('apple');
const orangeLogger = getLogger('orange');

generalLogger.log('info', 'general logger');
appleLogger.log('info', 'apple logger');
orangeLogger.log('info', 'orange logger');

So you export getLogger instead of just winston and then you'll get log messages like these:

info: [general] general logger
info: [apple] apple logger
info: [orange] orange logger

{"level":"info","message":"general logger","label":"general","timestamp":"2017-03-06T07:08:04.959Z"}
{"level":"info","message":"apple logger","label":"apple","timestamp":"2017-03-06T07:08:04.962Z"}
{"level":"info","message":"orange logger","label":"orange","timestamp":"2017-03-06T07:08:04.963Z"}

Hope this helps. Also here's a similar thread.