NestJS Instrumentation Library not Collecting Trace Data

[Nathan-Bernardo]

Hey guys,

I recently picked up opentelemetry and Jaeger for adding observability to my projects. I'm using NestJs as my backend platform. Previously, I was using the auto instrumentation library to use all the available instrumentations to collect any sort of trace data. I noticed that it had a nestjs-core instrumentation library to collect trace data of the controllers, but it never seems to show in Jaeger.

This is how I have everything setup:

tracer.ts

import { Resource } from '@opentelemetry/resources';
import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
import { SemanticResourceAttributes } from '@opentelemetry/semantic-conventions';
import * as opentelemetry from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { dockerCGroupV1Detector } from '@opentelemetry/resource-detector-docker';

const traceExporter = new OTLPTraceExporter();
const sdk = new opentelemetry.NodeSDK({
  traceExporter,
  instrumentations: [
    getNodeAutoInstrumentations({
      '@opentelemetry/instrumentation-express': {
        requestHook: (span, reqInfo) => {
          span.setAttribute(
            'request-headers',
            JSON.stringify(reqInfo.request.headers),
          );
        },
      },
    }),
  ],
  resourceDetectors: [dockerCGroupV1Detector],
  resource: new Resource({
    [SemanticResourceAttributes.SERVICE_NAME]: 'item_service',
  }),
});

sdk
  .start()
  .then(() => console.log('Tracing initialized'))
  .catch((error) => console.log('Error initializing tracing', error));

// gracefully shut down the SDK on process exit
process.on('SIGTERM', () => {
  sdk
    .shutdown()
    .then(() => console.log('Tracing terminated'))
    .catch((error) => console.log('Error terminating tracing', error))
    .finally(() => process.exit(0));
});

export default sdk;

main.ts

import { NestFactory } from '@nestjs/core';
import { Transport, MicroserviceOptions } from '@nestjs/microservices';
import { AppModule } from './app.module';
import tracer from './tracer';

async function bootstrap() {
  await tracer.start();
  const app = await NestFactory.create(AppModule);
  const microservice = app.connectMicroservice({
    transport: Transport.REDIS,
    options: {
      host: 'localhost',
      port: 6379,
    },
  });

  await app.startAllMicroservices();
  await app.listen(8080);
}
bootstrap();

I made no other configurations to the other files because I expected the auto instrumentation library to handle everything for me. The only trace data I get are from HTTP and Express instrumentation.

Any advice on things I may be missing?

Thanks!

[Flarna]

import tracer from './tracer'; should be the very first line in main.ts to ensure instrumentations are registered before the actual module is loaded. Once it's loaded it's to late...

Also tracer.start() should be called before you import nestjs,...

[Nathan-Bernardo]

This worked! Thanks for the advice @Flarna.

[behrad-kzm]

thanks helps a lot. the sdk must start before everything

[georg-schwarz]

I just had a similar issue. The problem was that we used a mono repo setup and bundle apps with esbuild.
That makes it hard to control whether the tracing is actually loaded before all other imports.

We ended up specifying an additionalEntryPoint to transpile a instrumatation.ts file side-by-side to our main.ts file.
Further, we used the node flag --require <path-to-instrumation.js> to preload the instrumentation.
This makes sure it also works with bundled setups (I assume it generalizes to other bundling processes as well).

You can find a working example here (last test app):
https://github.com/georg-schwarz/nestjs-instrumentation-example