log4js-node

NOTE: this documentation is for version 2.x, which is a work-in-progress. You probably want to look at version 1.1.1 docs instead.

This is a conversion of the log4js framework to work with node. I started out just stripping out the browser-specific code and tidying up some of the javascript to work better in node. It grew from there. Although it's got a similar name to the Java library log4j, thinking that it will behave the same way will only bring you sorrow and confusion.

The full documentation is available here.

Out of the box it supports the following features:

coloured console logging to stdout or stderr
file appender, with configurable log rolling based on file size or date
SMTP appender
GELF appender
Loggly appender
Logstash UDP appender
logFaces (UDP and HTTP) appender
multiprocess appender (useful when you've got worker processes)
a logger for connect/express servers
configurable log message layout/patterns
different log levels for different log categories (make some parts of your app log as DEBUG, others only ERRORS, etc.)

installation

npm install log4js

usage

Minimalist version:

var log4js = require('log4js');
var logger = log4js.getLogger();
logger.debug("Some debug messages");

By default, log4js outputs to stdout with the coloured layout (thanks to masylum), so for the above you would see:

[2010-01-17 11:43:37.987] [DEBUG] [default] - Some debug messages

See example.js for a full example, but here's a snippet (also in examples/fromreadme.js):

const log4js = require('log4js');
log4js.configure({
  appenders: { cheese: { type: 'file', filename: 'cheese.log' } },
  categories: { default: { appenders: ['cheese'], level: 'error' } }
});

const logger = log4js.getLogger('cheese');
logger.setLevel('ERROR');

logger.trace('Entering cheese testing');
logger.debug('Got cheese.');
logger.info('Cheese is Gouda.');
logger.warn('Cheese is quite smelly.');
logger.error('Cheese is too ripe!');
logger.fatal('Cheese was breeding ground for listeria.');

Output (in cheese.log):

[2010-01-17 11:43:37.987] [ERROR] cheese - Cheese is too ripe!
[2010-01-17 11:43:37.990] [FATAL] cheese - Cheese was breeding ground for listeria.

Documentation

Available here.

There's also an example application.

Contributing

Contributions welcome, but take a look at the rules first.

License

The original log4js was distributed under the Apache 2.0 License, and so is this. I've tried to keep the original copyright and author credits in place, except in sections that I have rewritten extensively.

zhuxindaba / log4js-node