Socket.IO + Nest.JS's `platform-socket.io` integration doesn't work

[ValeriyMaslenikov]

What version of OpenTelemetry are you using?

    "@opentelemetry/api": "^1.9.0",
    "@opentelemetry/auto-instrumentations-node": "^0.64.1",
    "@opentelemetry/exporter-metrics-otlp-grpc": "^0.205.0",
    "@opentelemetry/exporter-trace-otlp-grpc": "^0.205.0",
    "@opentelemetry/instrumentation-socket.io": "^0.52.0",
    "@opentelemetry/resources": "^2.1.0",
    "@opentelemetry/sdk-metrics": "^2.1.0",
    "@opentelemetry/sdk-node": "^0.205.0",
    "@opentelemetry/sdk-trace-node": "^2.1.0",
    "@opentelemetry/semantic-conventions": "^1.37.0",

What version of Node are you using?

v23.11.0

What did you do?

I have nestjs-pino installed.

instrumentation.ts:

import { NodeSDK } from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
...

const sdk = new NodeSDK({
 ...,
 instrumentations: [
   getNodeAutoInstrumentations()
 ],
});

sdk.start();

WS Gateway:

@WebSocketGateway()
export class TestWebSocketGateway {
  private readonly logger = new Logger(TestWebSocketGateway.name);
  @SubscribeMessage('test-socket-io-event-name')
  async handleGetGameInfo(): Promise<WsResponseDto<GameInfoDto>> {
    this.logger.log('Test event');
  }
}

What did you expect to see?

I expected to have the trace_id/span_id logged with Test event message, in the way how it works when socket.io library is used with .on('event-name', cb) .

What did you see instead?

I see the log logged, without any additional context from the OTLP instrumentation.

Additional context

Looks like the problem is related to how the Nest.JS subscribes on the socket.io listener.
It uses the rxjs fromEvent(socket, message) to do that.

Under the hood that function tries to "guess" which methods are available on the target object to register the "listener". Based on my observations for Nest.JS it goes to the branch of "node style event emitter":

which means that the condition on whether methods addListener/removeListener are present on socket.io "Socket" instance.

So eventually it uses the addListener and removeListener methods.
Based on the source code it looks like "@opentelemetry/instrumentation-socket.io" patches only on and emit methods.

Also, they define both on and addListener in their separate component emitter library: https://github.com/socketio/emitter/blob/main/lib/esm/index.js#L35C1-L42C1

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[pichlermarc]

@mottibec (component owner) - would you mind looking into this one? 🙂
I think it's very likely that what you described is the issue.