Logging Facility

Application Logging Abstraction Layer

$ yarn add logging-facility
$ npm install logging-facility --save

Features

• Abstraction Layer/Wrapper to easily exchange your logging backend without breaking your code
• Common used syslog levels are exposed as functions (emergency, alert, critical, error, warning, notice, info, debug)
• Multiple Loggers identified by name
• Ability to use multiple Backends
• All Logging functions are aggregated into a single callback

Usage

1. Application Startup/Configuration

This code sets up the logging-backend and should be executed within the application bootstrap

const _loggingFacility = require('logging-facility');
 
// use fancy colored cli output
_loggingFacility.addBackend('fancy-cli');

2. Logging

Within each of your application files you can access the global named loggers

// create/get a logger named "mylogger"
const _logger = require('logging-facility').getLogger('mylogger');
 
// log something
_logger.info('Initializing module X1', 'Additional Payload');
_logger.emergency('fatal error');

3. Custom Logging Backend

const _loggingFacility = require('logging-facility');
 
// only required for styling 
const _colors = require('colors/safe');
 
// set the logging backend/upstream
// every log message is passed to this function
_loggingFacility.setBackend(function(facility, level, args){
    // simple console output
    
    // log, info, debug
    if (level > 5){
        console.log(_colors.grey(facility.trim() + '~'), args.join(' '));
 
    // errors
    }else{
        console.log(_colors.red(facility.trim() + '~'), args.join(' '));
    }
});

Multiple Backends

const _loggingFacility = require('logging-facility');
 
// add logging backend for fatal errors
_loggingFacility.addBackend(function(facility, level, args){
   
   // send a e-mail on fatal errors occured
   if (level > 3){
        Mailer.notify(args[0]);
   }
});
 
// add fancy console output
_loggingFacility.addBackend('fancy-cli');

Methods/Syntax

::getLogger()

Description: Create a new logger

Syntax: logger:object = getLogger(name)

Arguments:

• name:string - the instance name of the logger, passed as first argument to the backend function

Returns:

An object with the following logging-functions

• emerg(...messages),
• emergency(...messages),
• alert(...messages),
• crit(...messages),
• critical(...messages),
• error(...messages),
• err(...messages),
• warning(...messages),
• warn(...messages),
• notice(...messages),
• log(...messages),
• info(...messages),
• debug(...messages),

Example:

// create/get a logger named "mylogger"
const _logger = require('logging-facility').getLogger('mylogger');
 
// log something
_logger.info('Initializing module X1', 'Additional Payload');
_logger.emergency('fatal error');

::addBackend()

Description: Adds a new backend logger to the stack

Syntax: setBackend(backend:function|string, [minLogLevel:int=99])

Arguments:

• backend:(function|string) - a callback function which will receive all log messages. all default loggers can be accessed by name (allowed values: fancy-cli, cli).
• minLogLevel:int=99 (optional) - the minimum log-level of the backend in case it's initialized by name not function

Example:

const _loggingFacility = require('logging-facility');
 
// add logging backend for fatal errors
_loggingFacility.addBackend(function(facility, level, args){
   
   // send a e-mail on fatal errors occured
   if (level > 3){
        Mailer.notify(args[0]);
   }
});
 
// add fancy console output
_loggingFacility.addBackend('fancy-cli');
 
// add simple cli output
_loggingFacility.addBackend('cli');

::setBackend()

DEPRECATED

Description: Removes all exsiting backends and add a new one to the stack

Syntax: setBackend(backend:function|string)

Arguments:

• backend:(function|string) - a callback function which will receive all log messages. all default loggers can be accessed by name.

Example:

const _loggingFacility = require('logging-facility');
 
// add fancy console output
_loggingFacility.addBackend('fancy-cli');
 
// add logging backend for fatal errors - WILL REMOVE the fancy-cli backend added previously!
_loggingFacility.setBackend(function(facility, level, args){
   
   // send a e-mail on fatal errors occured
   if (level > 3){
        Mailer.notify(args[0]);
   }
});

::LEVEL

Description: Constants used for different log-levels @see lib/loglevel.js

EMERGENCY: 0
ALERT: 1
CRITICAL: 2
ERROR: 3
WARNING: 4
NOTICE: 5
INFO: 6
DEBUG: 7

Example:

const _loggingFacility = require('logging-facility');
 
// get warning log-level
console.log(_loggingFacility.LEVEL.WARNING);

::LOGGER

Description: Build-In logging backends

CLI - simple cli logging
FANCY - colorized cli output
DEFAULT - alias of CLI

Example:

const _loggingFacility = require('logging-facility');
 
// add logging function with min-loglevel of 5
_loggingFacility.addBackend(_loggingFacility.LOGGER.CLI(_loggingFacility.LEVEL.NOTICE));

Any Questions ? Report a Bug ? Enhancements ?

Please open a new issue on GitHub

License

Logging-Facility is OpenSource and licensed under the Terms of The MIT License (X11). You're welcome to contribute!