This is a conversion of the log4js
Out of the box it supports the following features:
coloured console logging to stdout or stderr
replacement of node's console.log functions (optional)
file appender, with configurable log rolling based on file size or date
Logstash UDP 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.)
Important changes in 1.0
The default appender has been changed from console to stdout - this alleviates a memory problem that happens when logging using console. If you're using log4js in a browser (via browserify), then you'll probably need to explicitly configure log4js to use the console appender now (unless browserify handles process.stdout).
I'm also trying to move away from vows for the tests, and use tape instead. New tests should be added to test/tape, not the vows ones.
log4js also no longer supports node versions below 0.12.x.
NOTE: from log4js 0.5 onwards you'll need to explicitly enable replacement of node's console.log functions. Do this either by calling log4js.replaceConsole() or configuring with an object or json file like this:
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 fromreadme.js):
var log4js = require('log4js');
//console log is loaded bydefault, so you won't normally need to do this
var logger = log4js.getLogger('cheese');
logger.trace('Entering cheese testing');
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.');
[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.
The first 5 lines of the code above could also be written as:
You can configure the appenders and log levels manually (as above), or provide a
configuration file (log4js.configure('path/to/file.json')), or a configuration object. The
configuration file location may also be specified via the environment variable
LOG4JS_CONFIG (export LOG4JS_CONFIG=path/to/file.json).
An example file can be found in test/vows/log4js.json. An example config file with log rolling is in test/vows/with-log-rolling.json.
You can configure log4js to check for configuration file changes at regular intervals, and if changed, reload. This allows changes to logging levels to occur without restarting the application.
If you have already defined an absolute path for one of the FileAppenders in the configuration file, you could add a "absolute": true to the particular FileAppender to override the cwd option passed. Here is an example configuration file:
Contributions welcome, but take a look at the rules first.
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