Log-Tonic

Log-Tonic is an enterprise-grade, flexible logging utility for Node.js and TypeScript projects. It supports structured JSON logging, multiple transports (Console, File, etc.), log levels, and customizable formatting.

Features

• Enterprise Ready: Structured JSON logging out of the box for easy ingestion by tools like Splunk, ELK, etc.
• Transport System: Modular transport system. Writes to Console by default, but extensible to File, HTTP, etc.
• Rich Log Levels: Support for debug, info, warn, error, and fatal.
• Feature-Specific Logging: Create scoped loggers for different modules or features.
• TypeScript Support: Built with TypeScript for full type safety.

Installation

You can install Log-Tonic via npm:

npm install log-tonic

Usage

1. Initialize the Logger

Initialize the logger at the start of your application with the desired configuration:

import { LoggerFactory, ConsoleTransport, LogLevel } from 'log-tonic';

LoggerFactory.initialize({
  minLevel: LogLevel.DEBUG,
  appName: 'MyEnterpriseApp',
  transports: [
    new ConsoleTransport({ 
      useJson: true, // Enable structured JSON logging
      useColor: true // Enable colors for non-JSON output 
    })
  ]
});

2. Create Feature-Specific Loggers

Create a logger for a specific feature or module within your application:

const authLogger = LoggerFactory.createLogger('AuthService');

// Pass metadata object as the second argument
authLogger.info('User login successful', { userId: '12345', role: 'admin' });
authLogger.error('Login failed', { error: 'Invalid credentials' });

3. Log Levels

Available log levels in order of priority:

1. DEBUG
2. INFO
3. WARN
4. ERROR
5. FATAL

4. Custom Transports

You can create custom transports by implementing the Transport interface:

import { Transport, LogEntry } from 'log-tonic';

class MyCustomTransport implements Transport {
  log(entry: LogEntry): void {
    // Send log to external service
    console.log('Sending to cloud:', entry);
  }
}

Migration Guide (v1.0.x -> v1.1.0)

If you are upgrading from v1.0.1 or earlier, there are some breaking changes to support the new enterprise features.

1. Initialization Changes

The level property has been renamed to minLevel and now accepts a LogLevel enum instead of a string.

v1.0.0 (Old):

LoggerFactory.initialize({
  level: 'debug',
  appName: 'MyApp'
});

v1.1.0 (New):

import { LoggerFactory, LogLevel } from 'log-tonic';

LoggerFactory.initialize({
  minLevel: LogLevel.DEBUG, // Changed from string to Enum
  appName: 'MyApp'
  // Transports are optional, defaults to ConsoleTransport
});

2. Log Levels

We have moved from strict string types to an Enum for better type safety and added new levels.

• Old: 'debug', 'info', 'error'
• New: LogLevel.DEBUG, LogLevel.INFO, LogLevel.WARN, LogLevel.ERROR, LogLevel.FATAL

3. Creating Loggers

createLogger remains largely valid, but methods now support metadata objects.

// v1.0.0
logger.info('Message');

// v1.1.0
logger.info('Message'); // Still works
logger.info('Message', { meta: 'data' }); // New capability

Contributing

Contributions are welcome! Please follow these steps:

1. Fork the repository.
2. Create a feature branch (git checkout -b feature/my-feature).
3. Commit your changes (git commit -m 'Add my feature').
4. Push to the branch (git push origin feature/my-feature).
5. Open a pull request.

License

Log-Tonic is licensed under the Apache License, Version 2.0. See the LICENSE file for more details.

Links

• GitHub Repository
• npm Package