Introduction to Kosher Logger

The kosher-logger is a highly configurable and efficient logging library for Node.js applications. It offers a wide range of APIs to meet all your logging needs, making debugging and monitoring a breeze.

Why Choose Kosher Logger?

Kosher Logger is designed to be easy to use, extendable, and powerful. Whether you are building a small app or an enterprise-level service, this logger provides everything you need.

Installation

npm install kosher-logger

Basic Usage

Here’s a basic example of how to use Kosher Logger in your application.

const KosherLogger = require('kosher-logger');
const logger = new KosherLogger();

logger.info('This is an info message');
logger.error('This is an error message');
logger.debug('This is a debug message');

Configuration

You can customize the logger to suit your requirements.

const logger = new KosherLogger({
	level: 'debug',
	transport: 'console',
	timestamp: true,
	format: 'json'
});

Setting Log Levels

Log levels help in filtering the messages based on their severity.

logger.setLevel('warn');
logger.info('This info will not be logged');
logger.warn('This is a warning message');
logger.error('This is an error message');

Custom Transports

You can define custom transports to log messages in different ways (e.g., to a file, over HTTP).

const fileTransport = {
	type: 'file',
	options: {
		filename: 'logs/app.log',
	}
};

logger.addTransport(fileTransport);
logger.info('This message will be logged to a file');

Using Context

Context can be added to the logs for better traceability.

logger.withContext({ requestId: '12345' }).info('Request received');

Log Rotation

Log rotation prevents log files from becoming too large.

const rotatedFileTransport = {
	type: 'file',
	options: {
		filename: 'logs/app-%DATE%.log',
		datePattern: 'YYYY-MM-DD',
		maxSize: '20m',
		maxFiles: '14d'
	}
};

logger.addTransport(rotatedFileTransport);
logger.info('This message will be logged to a rotated file');

Error Handling

Systematically catch and log errors in your application.

process.on('uncaughtException', (error) => {
	logger.error('Uncaught Exception', { error });
});

process.on('unhandledRejection', (reason) => {
	logger.error('Unhandled Rejection', { reason });
});

Complete App Example

Below is a complete example of an application utilizing multiple features of the Kosher Logger.

const express = require('express');
const KosherLogger = require('kosher-logger');

const app = express();
const logger = new KosherLogger({
	level: 'debug',
	transports: [
		{ type: 'console' },
		{ type: 'file', options: { filename: 'logs/app.log' } }
	]
});

app.use((req, res, next) => {
	logger.withContext({ method: req.method, url: req.url }).debug('Request received');
	next();
});

app.get('/', (req, res) => {
	logger.info('Handling root route');
	res.send('Hello, world!');
});

app.use((err, req, res, next) => {
	logger.error('Error handling request', { err });
	res.status(500).send('Something went wrong');
});

app.listen(3000, () => {
	logger.info('Server started on port 3000');
});

With these configurations and examples, you now have a powerful and flexible logging setup for your Node.js applications using Kosher Logger!

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