kitten-logger v0.3.1

kitten-logger

Features

• Cluster Mode
• Log rotation
• Custom formatters by namespaces
• Support Debug library variables
• Filtering at runtime

Get started

Install

npm install kitten-logger

Log

const kittenLogger = require('kitten-logger');

kittenLogger.init();

let logger = kittenLogger.createPersistentLogger('http');

logger.info('My message to log');

Philosophy

A master process initializes kitten-logger (kittenLogger.init) to capture stdout and stderr from master process and forked processes if it is run in cluster mode. Then, it logs entries in log file in CSV format or directly in the terminal.

API

Log levels

• DEBUG
• INFO
• WARN
• ERROR

Environment variables

Initialisation kittenLogger.init

The initialisation function create the logs directory where the process has been launched. If it is in TTY mode, the logs are redirected to the terminal. Otherwise, the logs are writted to the file out.log. A rotation log system is enabled to rotate logs by day.

Loggers

kitten-logger differenciates two types of logger:

• persitent logger
• simple logger

kittenLogger.createPersistentLogger({String} namespace) -> {LoggerObject}

Create a persistent logger. It returns a logger Object.

Example

const kittenLogger = require('kitten-logger');

let logger = kittenLogger.createPersistentLogger('http');

logger.error(err);

kittenLogger.createLogger({String} namespace) -> {LoggerObject}

Create a persistent logger. It returns a logger Object.

Example

const kittenLogger = require('kitten-logger');

let logger = kittenLogger.createLogger('http');

logger.error(err);

LoggerObject

Methods

• LoggerObject.debug({String/Object} msg, {Object} options): log given message with level DEBUG.
• LoggerObject.info({String/Object} msg, {Object} options): log given message with level INFO.
• LoggerObject.warn({String/Object} msg, {Object} options): log given message with level WARN.
• LoggerObject.error({String/Object} msg, {Object} options): log given message with level ERROR.
• LoggerObject.extend({String} namespace) -> {LoggerObject}: extend the current logger, the namespace of the final LoggerObject will be the concatenation of the current one with the given parameter as parentNamespace:childNamespace. options is an Object, the key isKittenLogger can be set to follow logs through a chain of actions.

Terminal formatters

When displaying logs in terminal, formatters can be applied by namespaces.

kittenLogger.addFormatter({String} namespace, {Function} formatterFn)

Example

const kittenLogger = require('kitten-logger');

let logger = kittenLogger.createLogger('http');

kittenLogger.addFormatter('http', msg => {
  return msg.method + ' ' + msg.url;
});

...

// Logger, log the `req` object of an HTTP request
logger.log({ method : req.method, url : req.url });

kittenLogger.formattersCollection -> Object

Return a list of predefined formatters (/lib):

• http_start, log HTTP request
• http_end, log HTTP request's result

Filter

Kitten-logger allows you to filter namespaces & levels at runtime.

Static

Define the variable KITTEN_LOGGER.

process.env.KITTEN_LOGGER = 'onlyMyNamespace';

Define the variable KITTEN_LOGGER_LEVEL.

process.env.KITTEN_LOGGER_LEVEL = 'INFO';

Programatic

kittenLogger.filter({String} filter)

kittenLogger.filter('onlyMyNamespace');

kittenLogger.filterLevel({String} level)

kittenLogger.filterLevel('INFO');

Receive actions from outside the process

kitten-logger is allow to communicate between its pairs if exist in sub dependencies via socket.

To send action to kittenLogger instances, a process must connect to the given path, ex: /tmp/kitten_logger_<inode>. Where <inode> is the file descriptor's value of the master process.

The message must be of JSON type aand follow the given format :

{
  action : <ACTION>,
  value  : <value>
}

Where <ACTION> is a string, and <value> is the value for the action.

kittenLogger.listen()

Start a socket server. It must be run once in the master process.

kittenLogger.connect()

Connect to the socket server. It must be run once in the child process. If will attemp to connect to the socket server for 20 seconds.