Logger Helper

Powerful, flexible logging built on Winston - supports multiple transports, log levels, and hierarchical scopes.

Quick Reference

Feature	Description
Factory Method	LoggerFactory.getLogger(['scope1', 'scope2'])
Log Levels	error, alert, emerg, warn, info, http, verbose, debug, silly
Transports	Console (default), DailyRotateFile, UDP/Dgram
Scopes	Hierarchical context tracking (e.g., ['MyService', 'MyMethod'])

Common Methods

logger.info('message');      // Informational
logger.error('message');     // Error
logger.warn('message');      // Warning
logger.debug('message');     // Debug

Getting a Logger Instance

The recommended way to get a logger instance is by using the LoggerFactory.

import { LoggerFactory } from '@venizia/ignis';

const logger = LoggerFactory.getLogger(['MyService']);

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

Scopes

You can provide an array of scopes to the getLogger method to create a hierarchical logger. This is useful for identifying the source of log messages.

const logger = LoggerFactory.getLogger(['MyService', 'MyMethod']);
logger.info('This message is from MyService-MyMethod');

Configuration

The logger is configured through environment variables and the defineCustomLogger function, which sets up the winston instance.

Log Levels

The logger supports the following log levels (from highest to lowest priority): error, alert, emerg, warn, info, http, verbose, debug, silly.

Transports

Ignis comes with three main types of transports:

1. Console: Logs messages to the console. Enabled by default.
2. DailyRotateFile: Logs messages to files that are rotated on a daily or hourly basis.
3. Dgram (UDP): Sends log messages over UDP to a remote log aggregation service.

Environment Variables for Configuration

• APP_ENV_LOGGER_FOLDER_PATH: The directory to store log files.
• APP_ENV_APPLICATION_NAME: Used as a prefix for log files and as a label in log messages.
• APP_ENV_LOGGER_DGRAM_HOST: The host for the UDP log transport.
• APP_ENV_LOGGER_DGRAM_PORT: The port for the UDP log transport.
• APP_ENV_LOGGER_DGRAM_LABEL: A label to identify the source of UDP logs.
• APP_ENV_LOGGER_DGRAM_LEVELS: A comma-separated list of log levels to be sent via UDP (e.g., error,warn,info).

Example .env file:

APP_ENV_LOGGER_FOLDER_PATH=./app_data/logs
APP_ENV_LOGGER_DGRAM_HOST=127.0.0.1
APP_ENV_LOGGER_DGRAM_PORT=5000
APP_ENV_LOGGER_DGRAM_LABEL=my-app
APP_ENV_LOGGER_DGRAM_LEVELS=error,warn,info,debug

Custom Logger

While the default logger is powerful, you can create your own custom logger by extending the Logger class and providing a custom winston.Logger instance.

import { Logger, defineCustomLogger, applicationLogFormatter } from '@venizia/ignis';
import winston from 'winston';

const myCustomWinstonLogger = defineCustomLogger({
  loggerFormatter: applicationLogFormatter,
  transports: {
    info: { file: { prefix: 'my-app', folder: './logs' } },
    error: { file: { prefix: 'my-app-error', folder: './logs' } },
  },
});

const myLogger = new Logger({ customLogger: myCustomWinstonLogger });
myLogger.withScope('CustomScope').info('This is a custom log message.');