🪓 trace-reaper

> Distributed tracing decorator for NestJS (HTTP + Microservices) powered by OpenTelemetry —
> brought to you by Hell Factory 🔥


---

✨ Features

- ✅ @Span() decorator to auto-create spans for methods
- ✅ Supports both HTTP and NestJS microservice handlers
- ✅ Automatically extracts trace context from incoming headers or payload
- ✅ Integrates seamlessly with OpenTelemetry SDK
- ✅ Minimal + Flexible — zero business logic coupling

---

📦 Installation

``bash
npm install @hell-factory/trace-reaper
`

Example

`ts
// Register instead of Client Proxy
// attach headers in payload automation
import { Module } from '@nestjs/common';
import { Transport } from '@nestjs/microservices';
import { ReaperClientProxy } from '@hell-factory/trace-reaper';
import { AppController } from './app.controller';

@Module({
controllers: [AppController],
providers: [
{
provide: 'TODO_SERVICE',
useFactory: () => {
return new ReaperClientProxy({
transport: Transport.RMQ,
options: {
urls: ['amqp://@localhost:5672'],
queue: 'todo_queue',
},
});
},
},
],
})
export class AppModule {}

// Nestjs Http
import { Span } from '@hell-factory/trace-reaper';
import { Controller, Get, Req } from '@nestjs/common';
import { Request } from 'express';

@Controller()
export class HelloController {
@Get('/hello')
@Span() // ⬅️ Automatically creates a span named 'getHello'
getHello(@Req() req: Request) {
return 'Hello World!';
}
}
`

`ts
// NestJS Microservice (e.g. RMQ / TCP)
import { Span } from '@hell-factory/trace-reaper';
import { Controller } from '@nestjs/common';
import { MessagePattern, Payload } from '@nestjs/microservices';

@Controller()
export class UserEvents {
@MessagePattern('user.created')
@Span() // ⬅️ Span created using payload.headers as parent context
handleEvent(@Payload() payload: any) {
// payload._headers is removed by interceptor or span
return 'OK';
}
}
`

`ts
// Register as global interceptor
import { TraceInterceptor } from '@hell-factory/trace-reaper';

async function bootstrap() {
const app = await NestFactory.create(AppModule);
app.useGlobalInterceptors(new TraceInterceptor());
await app.listen(3000);
}

// Use Controller
@UseInterceptors(TraceInterceptor)
@Controller('user')
export class UserController {
@Get(':id')
getUser(@Param('id') id: string) {
return { id };
}
}
``