1. import { Controller, Get } from '@nestjs/common';
2. import { AppService } from './app.service';
3. import {
4.   trace,
5.   Span,
6.   propagation,
7.   context,
8.   createContextKey,
9. } from '@opentelemetry/api';
10.  
11. @Controller()
12. export class AppController {
13.   constructor(private readonly appService: AppService) {}
14.  
15.   @Get()
16.   async getHello() {
17.     const newTracer = trace.getTracer('user-serive');
18.  
19.     const ctx = context.active();
20.     const ctxKey = createContextKey('First ctx key');
21.     ctx.setValue(ctxKey, 'ctx1');
22.     const output = {};
23.     propagation.inject(ctx, output);
24.     console.log(output, ctx);
25.  
26.     const span1 = newTracer.startSpan('start1', {}, ctx);
27.     const spanCtx = span1.spanContext();
28.     await this.appService.getHello(spanCtx);
29.     span1.end();
30.  
31.     // let activeContext = propagation.extract(context.active(), {});
32.     // activeContext.getValue();
33.     const span2 = newTracer.startSpan('start2');
34.     this.appService.getHello2();
35.     span2.end();
36.   }
37. }