sentry and open telemetry with standard OTEL/W3CT propagation nodejs/nextjs

sentry.server.config.ts

// this file is loaded instrumentation.js via something like this:
// export async function register() {if (process.env.NEXT_RUNTIME === "nodejs"){await import("../sentry.server.config");}}

import { OTLPTraceExporter } from "@opentelemetry/exporter-trace-otlp-http";
import { Resource, resourceFromAttributes } from "@opentelemetry/resources";
import {
  W3CTraceContextPropagator,
  CompositePropagator,
} from "@opentelemetry/core";

import {
  NodeTracerProvider,
  SimpleSpanProcessor,
  ConsoleSpanExporter,
  BatchSpanProcessor,
} from "@opentelemetry/sdk-trace-node";
import * as Sentry from "@sentry/nextjs";
import { ATTR_SERVICE_NAME } from "@opentelemetry/semantic-conventions";
import { env } from "next-runtime-env";
import {
  SentryPropagator,
  SentrySampler,
  SentrySpanProcessor,
} from "@sentry/opentelemetry";
import { registerInstrumentations } from "@opentelemetry/instrumentation";
import { UndiciInstrumentation } from "@opentelemetry/instrumentation-undici";
import { Context, propagation, TextMapSetter } from "@opentelemetry/api";
// import { trace } from "@opentelemetry/api";

// uncomment this to see some extra debug info
// import { diag, DiagConsoleLogger, DiagLogLevel } from "@opentelemetry/api";
// diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.DEBUG);

// Initialize Sentry with custom OpenTelemetry setup
const sentryClient = Sentry.init({
  dsn: env("NEXT_PUBLIC_SENTRY_DSN"),
  environment: env("ENVIRONMENT"),
  skipOpenTelemetrySetup: true,
  tracesSampleRate: 1.0,

  // Setting this option to true will print useful information to the console while you're setting up Sentry.
  // true will only work if disableLogger is false in next.config.ts
  debug: false,
});

const otlpExporter = new OTLPTraceExporter({
  url: process.env.OTEL_EXPORTER_OTLP_ENDPOINT
    ? `${process.env.OTEL_EXPORTER_OTLP_ENDPOINT}/v1/traces`
    : "http://localhost:4318/v1/traces",
});

// https://docs.sentry.io/platforms/javascript/guides/node/opentelemetry/custom-setup/
const provider = new NodeTracerProvider({
  resource: resourceFromAttributes({
    [ATTR_SERVICE_NAME]: "your-service-name",
  }),
  // @ts-expect-error - SentrySampler is not typed correctly
  sampler: sentryClient ? new SentrySampler(sentryClient) : undefined,
  spanProcessors: [
    // new SimpleSpanProcessor(new ConsoleSpanExporter()),  // useful for debugging
    // @ts-expect-error - SentrySpanProcessor is not typed correctly
    new SentrySpanProcessor(),
    new BatchSpanProcessor(otlpExporter),
  ],
});

provider.register({
  propagator: new CompositePropagator({
    // W3CTraceContextPropagator is OTEL stadnard, makes sure that e.g. `traceparent` is included in requests
    propagators: [new W3CTraceContextPropagator(), new SentryPropagator()],
  }),
  contextManager: new Sentry.SentryContextManager(),
});

Sentry.validateOpenTelemetrySetup();

registerInstrumentations({
  // actually adds traceparent into headers when calling fetch
  instrumentations: [new UndiciInstrumentation()],
});


// ways to instrument your specific calls/code/... would be somewhere on the BE of your Node app (or e.g. NextJS backend)

// trace.getTracer("cohort-portal").startActiveSpan("test", (span) => {
//   console.log("test", span);
//   fetch("http://example.com")  // example.com should receive a request with header that has sentry-trace and traceparent
//   span.end();
// });

// also works, sentry recommends this
// Sentry.getClient()?.tracer.startActiveSpan("test", (span) => {
//   console.log("test 2", span);
//   span.end();
// });