NestJS Logitron

A lightweight, high-performance logging utility for NestJS applications, built on Pino and Winston, with execution time tracking, request tracing, and Kafka trace interception.

🚀 Features

• Execution Time Tracking: Measure and log the execution time of controllers and methods automatically.
• Request Logging Middleware: Capture incoming HTTP requests, including metadata like headers, query params, and response time.
• Trace Middleware: Ensure every request has a unique trace ID for better debugging and correlation.
• Logger Factory: Easily create custom loggers with flexible configurations.
• Multiple Logger Support: Choose between Pino (lightweight, high-performance) and Winston (multi-transport support) based on your needs.
• Automatic Logging Middleware: Log both incoming requests and outgoing responses effortlessly.
• Kafka Trace Interceptor: Automatically attach trace IDs to Kafka messages, ensuring full traceability across distributed services.

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Installation

Install via npm:

npm install nestjs-logitron

or via yarn:

yarn add nestjs-logitron

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🛠️ Usage

Setting Up the Logger in main.ts

You can initialize the logger with either PINO or WINSTON as the logging backend.

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { LoggerService } from 'nestjs-logitron';

async function bootstrap() {
  const app = await NestFactory.create(AppModule, { bufferLogs: true });
  app.useLogger(app.get(LoggerService));
  await app.listen(3000);
}

bootstrap().catch(console.error);

Configuring the Logger in app.module.ts

import { Module } from '@nestjs/common';
import { LoggerType, LoggerModule } from 'nestjs-logitron';
import { AppController } from './app.controller';
import { AppService } from './app.service';

@Module({
  imports: [
    LoggerModule.forRoot({
      type: LoggerType.PINO,
      options: {
        transport: {
          targets: [
            {
              target: 'pino-pretty',
              options: {
                destination: 'api.log',
                singleLine: true,
                colorize: false,
                translateTime: 'yyyy-mm-dd HH:MM:ss',
              },
            },
            {
              target: 'pino-pretty',
              options: {
                colorize: true,
                translateTime: 'yyyy-mm-dd HH:MM:ss',
              },
            },
          ],
        },
      },
    }),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

Using Logger in a Controller

import { Controller, Get, Logger } from '@nestjs/common';
import { AppService } from './app.service';
import { TraceIdHandler } from 'nestjs-logitron';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  private readonly logger = new Logger(AppController.name);

  @Get()
  async getHello() {
    this.logger.debug({ traceId: TraceIdHandler.getTraceId() });
    return this.appService.getWorld();
  }
}

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🔍 Why We Use async_hooks for Trace ID Storage

The Problem:

Handling trace IDs in asynchronous environments (like HTTP requests, DB queries, and background tasks) is difficult because global variables do not retain execution context.

The Solution:

Node.js async_hooks enables continuation-local storage (CLS), ensuring that each trace ID is bound to its originating request, even in async operations.

How It Works:

• A new async context is created per request.
• The trace ID is stored in this context and is automatically retained across async calls.
• No manual propagation is needed—every log within the request cycle contains the trace ID.

Express Middleware for Trace Injection

import { Injectable, NestMiddleware } from '@nestjs/common';
import { Request, Response, NextFunction } from 'express';
import { v4 as uuidv4 } from 'uuid';
import { TraceIdHandler, withTraceId } from 'nestjs-logitron';

@Injectable()
export class TraceMiddleware implements NestMiddleware {
  use(req: Request, _: Response, next: NextFunction) {
    const traceId = req.headers['x-trace-id'] || uuidv4();
    withTraceId(traceId, () => next());
  }
}

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🛠️ Kafka Trace Interceptor

Why Do We Need This?

In microservices architectures, messages pass through Kafka, but they lose their original HTTP request trace IDs. This makes debugging very difficult.

How It Works:

• Extracts traceId from Kafka messages (if present) or generates a new one.
• Stores traceId using async_hooks.
• Ensures all logs from Kafka handlers contain the correct traceId.

Implementation

import { CallHandler, ExecutionContext, Injectable, NestInterceptor } from '@nestjs/common';
import { Observable } from 'rxjs';
import { v4 as uuidv4 } from 'uuid';
import { TraceIdHandler, withTraceId } from 'nestjs-logitron';

@Injectable()
export class KafkaTraceInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    const payload = context.switchToRpc().getData();
    const traceId = payload?.traceId ?? uuidv4();
    
    return new Observable((subscriber) => {
      withTraceId(traceId, () => {
        next.handle().subscribe({
          next: (value) => subscriber.next(value),
          error: (err) => subscriber.error(err),
          complete: () => subscriber.complete(),
        });
      });
    });
  }
}

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📜 Log Output Format

[yyyy-mm-dd HH:MM:ss.MS] [log_level] [app_name] [trace_id] [message] [payload] [time_taken_MS]

Example:

[2025-03-18T06:30:20.156Z] [ERROR] [NESTJS-LOGITRON] [12345-trace-id] [Something went wrong] [N/A] [N/A]

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🤝 Contribution

We welcome contributions from the community! 🚀

Steps to Contribute:

1. Fork the repository.
2. Create a feature branch: git checkout -b feature-name.
3. Commit your changes: git commit -m "Added new feature".
4. Push the branch: git push origin feature-name.
5. Open a Pull Request.

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📜 License

nestjs-logitron is licensed under the MIT License.

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📞 Contact & Support

Have questions? Found an issue? Open an issue on GitHub or reach out!

Happy logging! 📜✨