json-logger

A configurable, secure logging module built on Winston for Node.js applications. This logger formats logs as JSON objects, supports custom log levels, sanitizes sensitive data, colorizes output, and provides structured JSON formatting. Ideal for multi-environment setups with security-focused logging.

Features

• Customizable log output levels based on NODE_ENV to control which log levels are recorded in different environments
• Colorized console output for enhanced readability
• JSON formatting for structured logs, with pretty-print options
• Sensitive data sanitization to prevent plain-text logging of sensitive fields
• Uncaught Exception & Rejection Handling for robust error logging

Installation

npm install @mccann-hub/json-logger

Usage

Basic Setup

Initialize the logger with default settings:

import Logger from '@mccann-hub/json-logger';

const logger = Logger();

// Logging examples
logger.info('Informational message');
logger.error('An error occurred', { error: new Error('Sample error') });

Configuration Options

Application Name

The logger will attempt to retrieve the application name in the following order of precedence:

1. From package.json (if it exists), using the name field.
2. From deno.json (if it exists), using the name field.
3. From the LOGGER_APP_NAME environment variable.

Example for setting LOGGER_APP_NAME:

export LOGGER_APP_NAME="MyAppName"

Log Output Levels

The logger adjusts output levels based on NODE_ENV:

• local / development: Logs all levels (debug and higher).
• local-test: Logs only error level by default.
• production: Logs info, http, warn, and error levels only.

The default level can also be overridden by setting WINSTON_LEVEL:

export WINSTON_LEVEL=debug

Sensitive Data Sanitization

Sanitize sensitive fields by specifying keys to redact:

const logger = Logger(undefined, ['SECRET', 'PASSWORD', 'TOKEN']);
logger.info('User login', { password: 'secret123', token: 'abc' });

Fields like user_password and api_token will appear as ***REDACTED*** in the logs.