Logger NestJS

A powerful and flexible logger module for NestJS with support for multiple transports, CLS integration, and daily log rotation.

Features

• Multiple Transports: Console and file transports
• Daily Log Rotation: Automatic daily log file creation
• CLS Integration: Request ID tracking via continuation-local storage
• Configurable Log Levels: Fine-grained control over log verbosity
• TypeScript Support: Fully typed for better developer experience
• Flexible Configuration: Easy to configure and extend

Installation

npm install logger-nestjs
# or
yarn add logger-nestjs
# or
pnpm add logger-nestjs

Quick Start

1. Register the Module

import { Module } from '@nestjs/common'
import { LoggerModule, LogLevel } from 'logger-nestjs'

@Module({
  imports: [
    LoggerModule.register({
      level: LogLevel.LOG,
      transports: [
        {
          type: 'console',
          enabled: true,
          options: {
            colorize: true,
          },
        },
        {
          type: 'file',
          enabled: true,
          options: {
            dirname: 'logs',
          },
        },
      ],
    }),
  ],
})
export class AppModule {}

2. Use the Logger

import { Injectable } from '@nestjs/common'
import { LoggerService } from 'logger-nestjs'

@Injectable()
export class AppService {
  constructor(private readonly logger: LoggerService) {
    this.logger.setContext('AppService')
  }

  getHello(): string {
    this.logger.log('Hello World')
    this.logger.error('Something went wrong')
    this.logger.warn('Warning message')
    this.logger.debug('Debug message')
    return 'Hello World'
  }
}

Configuration

LoggerConfig

interface LoggerConfig {
  level: LogLevel
  transports: TransportConfig[]
  clsRequestIdKey?: string
}

Log Levels

enum LogLevel {
  FATAL = 0,
  ERROR = 1,
  WARN = 2,
  LOG = 3,
  VERBOSE = 4,
}

Transport Types

Console Transport

{
  type: 'console',
  enabled: true,
  options: {
    colorize: boolean
  }
}

File Transport

{
  type: 'file',
  enabled: true,
  options: {
    dirname: string // Directory to store log files
  }
}

File transport automatically creates daily log files in the format: app-YYYY-MM-DD.log

CLS Integration

The logger integrates with nestjs-cls to track request IDs across your application.

Setup CLS

import { Module } from '@nestjs/common'
import { ClsModule } from 'nestjs-cls'
import { LoggerModule, LogLevel } from 'logger-nestjs'

@Module({
  imports: [
    ClsModule.forRoot({
      global: true,
      middleware: { mount: true },
    }),
    LoggerModule.register({
      level: LogLevel.LOG,
      transports: [
        {
          type: 'console',
          enabled: true,
        },
      ],
      clsRequestIdKey: 'Request-Id-In-App', // Optional, defaults to 'Request-Id-In-App'
    }),
  ],
})
export class AppModule {}

Set Request ID

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common'
import { Observable } from 'rxjs'
import { ClsService } from 'nestjs-cls'

@Injectable()
export class RequestIdInterceptor implements NestInterceptor {
  constructor(private readonly cls: ClsService) {}

  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    const request = context.switchToHttp().getRequest()
    const requestId = request.headers['x-request-id'] || generateUniqueId()
    this.cls.set('Request-Id-In-App', requestId)
    return next.handle()
  }
}

Decorators

LoggerContext

Use the @LoggerContext() decorator to set the logger context:

import { Injectable } from '@nestjs/common'
import { LoggerService, LoggerContext } from 'logger-nestjs'

@Injectable()
@LoggerContext('MyService')
export class MyService {
  constructor(private readonly logger: LoggerService) {}

  doSomething() {
    this.logger.log('This will have context "MyService"')
  }
}

License

MIT