jayakarra / log4js-node

A port of log4js to node.js

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've mainly stripped out the browser-specific code and tidied up some of the javascript. 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.

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.

You can also see a full Express application example in log4js-example.

Documentation for most of the core appenders can be found on the wiki, otherwise take a look at the tests and the examples.

Documentation

See the wiki. Improve the wiki, please.

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.