log4js-node

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.

Changes in version 3.x

Migrating from log4js < v2.x?

There have been a few changes between log4js 1.x and 2.x (and 0.x too). You should probably read this migration guide if things aren’t working.

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
• TCP appender (useful when you’ve got multiple servers but want to centralise logging)
• 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.)
• built-in support for logging with node core’s cluster module
• third-party InfluxDB appender

Installation

npm install log4js

Usage

Minimalist version:

var log4js = require("log4js");
var logger = log4js.getLogger();
logger.level = "debug"; // default level is OFF - which means no logs at all.
logger.debug("Some debug messages");

Clustering

If you use node’s cluster, or passenger, or pm2, then you should read this clustering guide

Note for library makers

If you’re writing a library and would like to include support for log4js, without introducing a dependency headache for your users, take a look at log4js-api.

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.