📑 Structured Logger Module

A production-ready logging module for NestJS built on top of Winston. Features:

• ✅ Global NestJS module (StructuredLoggerModule)
• ✅ Works across HTTP, RPC, and WebSocket with an interceptor
• ✅ Correlation ID injection (via @nestified/correlation-id)
• ✅ Redaction of sensitive fields
• ✅ Console + File transports
• ✅ Environment-aware formatting (colorized in dev, JSON in prod)

📦 Installation

npm install @nestified/centralized-logger
# or
pnpm add @nestified/centralized-logger
# or
yarn add @nestified/centralized-logger

🛠 Setup

Register the logger module in your root module:

import { Module } from '@nestjs/common';
import { StructuredLoggerModule } from './logger/structured-logger.module';

@Module({
  imports: [
    StructuredLoggerModule.registerAsync({
      imports: [ConfigModule],
      useFactory: async (configService: ConfigService) => ({
        serviceName: configService.get('serviceName', 'serviceName'),
        injectCorrelationId: true, // install and setup @nestified/correlation-id
        level: configService.get('LOG_LEVEL', 'info'),
        logDir: configService.get('LOG_DIR'),
        environment: configService.get('ENV', 'development'),
        redactFields: ['password', 'authorization'],
      }),
      inject: [ConfigService],
    }),
  ],
})
export class AppModule {}

🚀 Use Logger in Bootstrap

Enable the structured logger in your main.ts bootstrap file:

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  app.useLogger(app.get(StructuredLoggerService));

  await app.listen(3000);
}

🔌 Usage

Inject logger into any provider

import { Injectable } from '@nestjs/common';

@Injectable()
export class UsersService {
  constructor(private readonly logger: Logger) {}

  getUser(id: string) {
    this.logger.log(`Fetching user ${id}`, UsersService.name); // now you're using StructuredLoggerService
    return { id, name: 'John Doe' };
  }
}

Logging methods

this.logger.log('hello world', 'MyContext');
this.logger.error('something went wrong', 'stacktrace here', 'AuthService');
this.logger.warn('deprecated method used', 'LegacyModule');
this.logger.debug('payload received', 'WebhookService');
this.logger.verbose('detailed debug info', 'JobProcessor');

🌐 Request/Response Logging

StructuredLoggerInterceptor automatically logs incoming requests and responses for HTTP, RPC, and WS.

Example log (production mode):

```json
{
  "context": "StructuredLoggerInterceptor",
  "correlationId": "b186776f-8d68-4745-b5b2-4b711d4ddfe3",
  "level": "info",
  "message": {
    "context": "HTTP",
    "message": "[HTTP] GET / - incoming",
    "metadata": {
      "headers": {
        "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,_/_;q=0.8",
        "accept-encoding": "gzip, deflate, br, zstd",
        "accept-language": "en-US,en;q=0.5",
        "connection": "keep-alive",
        "host": "localhost:8000",
        "if-none-match": "W/\"38-EkWGXeI7T6OCd6tPcOz4ZqERshw\"",
        "priority": "u=0, i",
        "sec-fetch-dest": "document",
        "sec-fetch-mode": "navigate",
        "sec-fetch-site": "none",
        "sec-fetch-user": "?1",
        "upgrade-insecure-requests": "1",
        "user-agent": "Mozilla/5.0 (X11; Linux x86_64; rv:141.0) Gecko/20100101 Firefox/141.0"
      },
      "ip": "::ffff:127.0.0.1"
    },
    "payload": {}
  },
  "service": "my-service",
  "timestamp": "2025-08-24T12:23:18.007Z"
}

{
  "context": "StructuredLoggerInterceptor",
  "correlationId": "b186776f-8d68-4745-b5b2-4b711d4ddfe3",
  "level": "info",
  "message": {
    "context": "HTTP",
    "message": "[HTTP] GET / - completed in 0ms",
    "response": { "PING": "PONG" }
  },
  "service": "my-service",
  "timestamp": "2025-08-24T12:23:18.007Z"
}

🔒 Redaction

Redacts sensitive fields in both string messages and structured objects.

redactFields: ['password', 'authorization'];

Output:

{
  "timestamp": "2025-08-24T11:00:00.000Z",
  "level": "info",
  "message": "User login",
  "payload": {
    "username": "john",
    "password": "[REDACTED]"
  }
}

🧩 Options

export interface ILoggerOptions {
  serviceName: string;
  injectCorrelationId: boolean;
  environment?: 'development' | 'production' | 'staging';
  level?: 'info' | 'debug' | 'warn' | 'error';
  redactFields?: string[];
  logDir?: string;
}

📂 Log Files

When logDir is set:

• combined.log → all logs
• error.log → error logs only

✅ Summary

• Import StructuredLoggerModule once (global).
• Inject Logger wherever you need it.
• Request/response logging is automatic with the interceptor.
• Logs are structured, redact sensitive data, and include correlation IDs.

📄 License

MIT © 2025 — Nestified