sugoi-logger

📝 Javascript logging module with support for syslog RFC5424 and json log format.

Features

• Supports syslog and json logging format.
• Custom format is also supported with options.formatter
• Adds an unique requestId to log messages. Can be used with express APIs.
• Adds info about line number and filename to log messages.
• Logging levels: {emergency|alert|critical|error|warning|notice|info|debug}
• Supports custom transports. By default it prints messages as stdout/stderr

Installation

npm install sugoi-logger --save

Usage

Set LOGGING_TYPE env variable to set logType. Logtype defaults to SYSLOG if not set.

export LOGGING_TYPE=JSON

Create your own logger and export it:

// main.js
import { Logger, setRequestId } from 'logging';

// create logger instance 
export const logger = new Logger({
    application: 'my-application' // custom application name
});

// Use setRequestId function to persist messageId in CLS within the callback function. Logger will pick up the context from this.
// example as express middleware
app.use((_req, _res, next) => setRequestId(next));

// example with other functions
function doSomething() {
   setRequestId(() => {
      doingSomething();
   })
}

// example with custom messageId
app.use((req, _res, next) => setRequestId(next, req.headers.messageId));

Use the logger instance:

// routes/list.js
import { logger } from './main';
import { v4 as uuidv4 } from 'uuid';

function getList () {
    // log the message. by default it will format messages into syslog RFC5424 and prints it in stdout
    logger.info('log message');

    // usage with structured data (can be set in data field)
    logger.error('log message', { meta: { user: { id: '1234' } } });
}

Options

Syntax

logger.info('log message', { key: value })

key	value	note
data	{ [ sdId : string ] : Record < string | number , any > }	additional properties for this logger. If LOGGING_TYPE is syslog, this will be printed as structured data.
context	{ [key:string]: any }	context of this log message in key-value format. Can be used in custom formatter
transports	(( arg : FormatterOptions ) => void)[]	set of logging transport functions
formatter	( arg : FormatterOptions ) => string	formatter function for log message