Fastify instrumentation not working for named import for ESM

[andreiborza]

What version of OpenTelemetry are you using?

@opentelemetry/instrumentation-fastify 0.36.1

What version of Node are you using?

v18.19

What did you do?

opentelemetry.mjs:

import { register } from 'module';
register('@opentelemetry/instrumentation/hook.mjs', import.meta.url);

import {
  diag,
  DiagConsoleLogger,
  DiagLogLevel,
} from '@opentelemetry/api';

diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.WARN);

import { HttpInstrumentation } from '@opentelemetry/instrumentation-http';
import { FastifyInstrumentation } from '@opentelemetry/instrumentation-fastify';

import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-proto';
import { OTLPMetricExporter } from '@opentelemetry/exporter-metrics-otlp-proto';
import { NodeSDK, metrics } from '@opentelemetry/sdk-node';

const sdk = new NodeSDK({
  instrumentations: [
    HttpInstrumentation,
    new FastifyInstrumentation(),
  ],
  traceExporter: new OTLPTraceExporter(),
  metricReader: new metrics.PeriodicExportingMetricReader({
    exporter: new OTLPMetricExporter(),
  }),
});

process.on('beforeExit', async () => {
  await sdk.shutdown();
});

sdk.start();

app.mjs with named import:

import { fastify } from "fastify";
import { isWrapped} from "@opentelemetry/core";

const app = fastify()
app.listen({ port: 3000 })

console.log(isWrapped(app.addHook)) 
// -> false

app.mjs with default import:

import fastify from "fastify";
import { isWrapped} from "@opentelemetry/core";

const app = fastify()
app.listen({ port: 3000 })

console.log(isWrapped(app.addHook))
// -> true

ran with
node --import ./opentelemetry.mjs app.mjs

What did you expect to see?

The named export of fastify to be correctly instrumented (isWrapped(app.addHook) to return true), like the second instance of app.mjs with the default import of fastify.

What did you see instead?

fastify was not instrumented correctly, isWrapped(app.addHook) returned false.

Additional context

First came up in our SDK: getsentry/sentry-javascript#12119