Reusable Winston Logger

A professional, opinionated Winston logger module for NestJS, featuring daily file rotation and environment-aware configuration.

Features

• Daily File Rotation: Automatically manages log files with rotation (combined and error logs).
• Environment Aware: Configurable via .env variables or standard NestJS module options.
• Bootstrapping Support: Easily use the logger as the main NestJS application logger from the start.
• Async Configuration: Supports forRootAsync for integration with ConfigService.
• Pre-configured Formats: Professional "Nest-like" console output for development and JSON for production.

Installation

npm install reusable-winston-logger

Quick Start (Bootstrap)

To use this logger as the primary NestJS logger for bootstrapping:

// main.ts
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { LoggerModule } from 'reusable-winston-logger';
 
async function bootstrap() {
  const app = await NestFactory.create(AppModule, {
    // This ensures even the internal NestJS logs use your custom Winston logger
    logger: LoggerModule.createLogger({
      serviceName: 'my-app-name',
    }),
  });
  await app.listen(3000);
}
bootstrap();

Configuration

Synchronous Usage

// app.module.ts
import { Module } from '@nestjs/common';
import { LoggerModule } from 'reusable-winston-logger';
 
@Module({
  imports: [
    LoggerModule.forRoot({
      level: 'debug',
      serviceName: 'my-app',
      logDir: 'logs',
      maxFiles: '14d',
      maxSize: '20m',
    }),
  ],
})
export class AppModule {}

Asynchronous Usage (Recommended)

// app.module.ts
import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { LoggerModule } from 'reusable-winston-logger';
 
@Module({
  imports: [
    ConfigModule.forRoot(),
    LoggerModule.forRootAsync({
      imports: [ConfigModule],
      useFactory: (configService: ConfigService) => ({
        level: configService.get('LOG_LEVEL'),
        serviceName: 'my-app',
      }),
      inject: [ConfigService],
    }),
  ],
})
export class AppModule {}

Options

| Option | Type | Default | Description | | :--- | :--- | :--- | :--- | | level | string | info (prod) / debug (dev) | Minimum logging level | | serviceName | string | nestjs-app | Name of the service for meta data | | logDir | string | logs | Directory where log files will be stored | | maxFiles | string | 14d | Retention period for log files | | maxSize | string | 20m | Maximum size of a single log file | | winstonOptions| winston.LoggerOptions | undefined | Custom winston options to merge | | instance | winston.Logger | undefined | Pre-created winston instance |

Environment Variables

The package automatically looks for these variables if options are not provided:

• LOG_LEVEL
• LOG_MAX_FILES
• LOG_MAX_SIZE
• SERVICE_NAME
• LOG_DIR
• NODE_ENV (used to toggle console colors and level defaults)

Usage in Services

import { Injectable } from '@nestjs/common';
import { AppLoggerService } from 'reusable-winston-logger';
 
@Injectable()
export class MyService {
  constructor(private readonly logger: AppLoggerService) {}
 
  doSomething() {
    this.logger.log('Doing something...', 'MyService');
    this.logger.error('Something went wrong!', 'Stacktrace', 'MyService');
    this.logger.debug('Debugging info...', 'MyService');
  }
}