cedar

Cedar

TL;DR

Cedar is a Node.js logger, designed to be fast, extensible, and super useful.

Powerful features

• Modifiable logging prefixes, formatters, and stringify functions.
• Loggers which are functions, allowing shorthand calls.
• A console transport with color unicode symbols and helpful code snippets inside stack traces.
• A file transport that can rotate by day, hour or minute.
• A multi transport, which supports cluster, sending worker logs to the master process.

Quick Start

Add cedar to your dependencies.

npm install --save cedar

Create a logger, and use it.

var log = require('cedar')([
  {
    transport: 'console' // Default.
    level: 'trace' // Default.
  },
  {
    transport: 'file',
    level: 'info',
    path: 'log/${YYYY}/${MM}/${DD}/app_${HOST}.log'
  }
]);

log('Log a string'); // Shorthand.
log.debug(['or', 'an', 'array']);
log.trace({or: 'JSON of course'});
log.log('and', 'multiple', 'arguments', 'are', 'supported.', true);
log.info('This message will also log to file, based on `level`.')

log.trace('This gets formatted as a trace message, with a stack trace');
log.debug('This gets formatted as a debug message.');
log.log('This gets formatted as a log message.');
log.info('This gets formatted as an info message.');
log.warn('This gets formatted as a warning message.', error);
log.error('This gets formatted as an error message.', error);
log.alert('This gets formatted as an alerting message.', error);

Convention & Configuration

Each Cedar transport has properties with defaults that can be overridden using a config object. They also have getters and setters, allowing you to change them later.

For example:

// Set the log `level` in a configuration object.
var log = require('cedar')({level: 'warn'}); // "warn", "error" and "alert".

log('log');         // Ignore.
log.error('error'); // Log "error".

// Assign the `level`, thereby invoking its setter.
log.level = 'debug';

log('log');         // Log "log".
log.error('error'); // Log "error".
log.trace('trace'); // Ignore.

log.level string

Configures the minimum level of logging that is shown (default: trace).

var log = require('cedar')();
log.level = 'debug';

Setting to a level from this list will enable logs of that level and all of the levels after it: debug, trace, log, info, warn, error. Setting the level to nothing will stop all logs.

log.prefixes object

Customize prefixes for the color log messages.

require('colors');

var log = require('cedar')();
log.prefixes = {
  trace: 'TRACE: '.cyan,
  debug: 'DEBUG: '.magenta,
  log:   'LOG:   '.grey,
  info:  'INFO:  '.green,
  warn:  'WARN:  '.yellow,
  error: 'ERROR: '.red,
  alert: 'ALERT: '.red
};

log.space string

Configures the spacing that stringify uses.

var log = require('cedar')();
log.space = '  ';

The default is two spaces.

log.format function

Customize the message format, given 3 arguments.

var log = require('cedar')();
log.format = function (message, prefix, type) {
  return prefix + message + ' from log.' + type + '!';
});
log.info('Hello'); // "INFO Hello from log.info!"

Transports

Cedar currently supports 4 main transports: "base", "console", "file" and "multi". Each transport takes an optional configuration object.

Base

The base transport writes to a stream, and other transports extend it.

var fs = require('fs');
var writeStream = fs.createWriteStream('my.log');
var base = require('cedar')('base', {stream: writeStream});
base.log('Write this string to `my.log`');

Console

The console logger writes to process.stdout with pretty colors.

Console is the default transport, so the following are equivalent:

logger = require('cedar')();
logger = require('cedar')('color');

File

The file logger writes JSON messages to a file. In addition, it acts as a simple event emitter so you can receive notifications when file rotation events occur.

var file = require('cedar')('file', {
  path: 'log/app_${YYYY}-${MM}-${DD}_${HH}:${NN}_${HOST}.log'
});
file.info('This will go into a file.');

var console = require('cedar')();

file.on('open', function (path) {
  console.log('Opened "' + path + '" for logging.');
});

file.on('close', function (path) {
  console.log('Closed "' + path + '".');
});

Multi

The multi logger writes to multiple loggers at once. Its configuration object is an array of configurations with transports specified by a transport property.

var log = require('cedar')([
  {transport: 'console'},
  {transport: 'file', level: 'info', path: 'log/app_${YYYY}-${MM}-${DD}_${HOST}.log'},
  {transport: 'file', level: 'error', path: 'log/${YYYY}/${MM}/${DD}/error_${HOST}.log'}
]);

Acknowledgements

We would like to thank all of the amazing people who use, support, promote, enhance, document, patch, and submit comments & issues. Cedar couldn't exist without you.

Additionally, huge thanks go to TUNE for employing and supporting Cedar project maintainers, and for being an epically awesome place to work (and play).

MIT License

Copyright (c) 2014 Sam Eubank

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

How to Contribute

We welcome contributions from the community and are happy to have them. Please follow this guide when logging issues or making code changes.

Logging Issues

All issues should be created using the new issue form. Please describe the issue including steps to reproduce. Also, make sure to indicate the version that has the issue.

Changing Code

Code changes are welcome and encouraged! Please follow our process:

1. Fork the repository on GitHub.
2. Fix the issue ensuring that your code follows the style guide.
3. Add tests for your new code, ensuring that you have 100% code coverage. (If necessary, we can help you reach 100% prior to merging.)
   • Run npm test to run tests quickly, without testing coverage.
   • Run npm run cover to test coverage and generate a report.
   • Run npm run report to open the coverage report you generated.
4. Pull requests should be made to the master branch.

Contributor Code of Conduct

As contributors and maintainers of Cedar, we pledge to respect all people who contribute through reporting issues, posting feature requests, updating documentation, submitting pull requests or patches, and other activities.

If any participant in this project has issues or takes exception with a contribution, they are obligated to provide constructive feedback and never resort to personal attacks, trolling, public or private harassment, insults, or other unprofessional conduct.

Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, edits, issues, and other contributions that are not aligned with this Code of Conduct. Project maintainers who do not follow the Code of Conduct may be removed from the project team.

Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by opening an issue or contacting one or more of the project maintainers.

We promise to extend courtesy and respect to everyone involved in this project regardless of gender, gender identity, sexual orientation, ability or disability, ethnicity, religion, age, location, native language, or level of experience.