caterpillar

Caterpillar

Caterpillar is the ultimate logging system for Node.js, based on transform streams you can log to it and pipe the output off to different locations, including some pre-made ones. Caterpillar also supports log levels according to the RFC standard, as well as line, method, and file fetching for messages. You can even use it in web browsers with the Browser Transform.

Install

NPM

• Use: require('caterpillar')
• Install: npm install --save caterpillar

Browserify

• Use: require('caterpillar')
• Install: npm install --save caterpillar
• CDN URL: //wzrd.in/bundle/caterpillar@2.0.9

Ender

• Use: require('caterpillar')
• Install: ender add caterpillar

Usage

Example with the Filter and Human transforms

// Import
var level   = process.argv.indexOf('-d') === -1 ? 6 : 7;
var logger  = require('caterpillar').createLogger({level:level});
var filter  = require('caterpillar-filter').createFilter();
var human   = require('caterpillar-human').createHuman();

// Where to output?
if ( process.title === 'browser' ) {
	// Include the browser compatibility layer
	var browser = require('caterpillar-browser').createBrowser();

	// Pipe to filter to human to browser
	logger.pipe(filter).pipe(human).pipe(browser);
}
else {
	// Pipe to filter to human to stdout
	logger.pipe(filter).pipe(human).pipe(process.stdout);

	// If we are debugging, then write the original logger data to debug.log
	if ( level === 7 ) {
		logger.pipe(require('fs').createWriteStream('./debug.log'));
	}
}

// Log messages
logger.log('emergency', 'this is level 0');
logger.log('emerg', 'this is level 0');
logger.log('alert', 'this is level 1');
logger.log('critical', 'this is level 2');
logger.log('crit', 'this is level 2');
logger.log('error', 'this is level 3');
logger.log('err', 'this is level 3');
logger.log('warning', 'this is level 4');
logger.log('warn', 'this is level 4');
logger.log('notice', 'this is level 5');
logger.log('note', 'this is level 5');
logger.log('info', 'this is level 6');
logger.log('default', 'this is level 6');
logger.log('debug', 'this is level 7');
logger.log('this is level 6, the default level');
logger.log('you','can','also','use','as','many','arguments','as','you','want',1,[2,3],{four:5});

Result with log level 6 (info):

Result with log level 7 (debug):

Result with log level 7 (debug) in the browser with the Browser Transform

Transform API, extends stream.Transform

new (require('caterpillar').Transform)(config)

• Methods
  • constructor(config?) create our new instance with the config, config is optional
  • pipe(child) pipe our stream to the child, also sync our config to it
  • setConfig(config) set the configuration and emit the config event
  • getConfig() get the configuration
  • format(entry) format the caterpillar logger entry
• Configuration
  • none by default
• Events
  • config(config) emitted once our configuration has updated

Logger API, extends Transform API

new (require('caterpillar').Logger)(config)

• Methods

  • constructor(config?) create our new instance with the config, config is optional

  • log(args...) write a log message, the first argument is suppose to be the level (will use the default level if it isn't)

  • format(level, args...) create a log entry ready for writing to the logger stream, output is as follows:

    {
    	"args": ["this is emergency and is level 0"],
    	"date": "2013-04-25T10:18:25.722Z",
    	"levelNumber": 0,
    	"levelName": "emergency",
    	"line": "59",
    	"method": "Task.fn",
    	"file": "/Users/balupton/Projects/caterpillar/out/test/caterpillar-test.js"
    }
    

  • getLevelNumber(name) get the level number for the level name

  • getLevelName(number) get the level name for the level number

  • getLevelInfo(nameOrNumber) get the level name and number for either a level name or number

  • getLineInfo() get the file, method, and line that the log method was called on

• Configuration

  • lineOffset the amount of lines to offset when doing our line detection, useful for wrappers, defaults to 0

  • levels the level names and their associated number, also includes default for when no level was specified, defaults to:

    {
    	emergency: 0,
    	alert: 1,
    	critical: 2,
    	error: 3,
    	warning: 4,
    	notice: 5,
    	info: 6,
    	debug: 7,
    
    	emerg: 0,
    	crit: 2,
    	err: 3,
    	warn: 4,
    	note: 5,
    
    	default: 6
    }
    

• Events

  • only those inherited

History

Discover the change history by heading on over to the HISTORY.md file.

Backers

Maintainers

These amazing people are maintaining this project:

• Benjamin Lupton [e-mail] (https://github.com/balupton)

Sponsors

No sponsors yet! Will you be the first?

Contributors

These amazing people have contributed code to this project:

• Benjamin Lupton [e-mail] — view contributions
• t-visualappeal — view contributions
• thelfensdrfer — view contributions

Become a contributor!

License

Licensed under the incredibly permissive MIT license

Copyright © 2012+ Bevry Pty Ltd [e-mail] (http://bevry.me)
Copyright © 2011 Benjamin Lupton [e-mail] (http://balupton.com)

Changelog

v2.0.9 2015 February 18

• Fixed an issue when fetching (new Error()).stack would fail
• More robust stack parsing