use fastify hook instead of reading from span name

Author: Lms24

dev-packages/e2e-tests/test-applications/node-fastify-app/tests/transactions.test.ts

@@ -56,6 +56,23 @@ test('Sends an API route transaction', async ({ baseURL }) => {
   expect(transactionEvent).toEqual(
     expect.objectContaining({
       spans: [
+        {
+          data: {
+            'plugin.name': 'fastify -> sentry-fastify-error-handler',
+            'fastify.type': 'middleware',
+            'hook.name': 'onRequest',
+            'otel.kind': 'INTERNAL',
+            'sentry.origin': 'manual',
+          },
+          description: 'middleware - fastify -> sentry-fastify-error-handler',
+          parent_span_id: expect.any(String),
+          span_id: expect.any(String),
+          start_timestamp: expect.any(Number),
+          status: 'ok',
+          timestamp: expect.any(Number),
+          trace_id: expect.any(String),
+          origin: 'manual',
+        },
         {
           data: {
             'plugin.name': 'fastify -> sentry-fastify-error-handler',

packages/node/src/integrations/tracing/fastify.ts

@@ -1,10 +1,8 @@
 import { registerInstrumentations } from '@opentelemetry/instrumentation';
-import type { FastifyRequestInfo } from '@opentelemetry/instrumentation-fastify';
 import { FastifyInstrumentation } from '@opentelemetry/instrumentation-fastify';
-import { captureException, defineIntegration, getIsolationScope, spanToJSON } from '@sentry/core';
+import { captureException, defineIntegration, getCurrentScope, getIsolationScope } from '@sentry/core';
 import type { IntegrationFn } from '@sentry/types';
 
-import type { Span } from '@opentelemetry/api';
 import { addOriginToSpan } from '../../utils/addOriginToSpan';
 
 const _fastifyIntegration = (() => {
@@ -14,9 +12,8 @@ const _fastifyIntegration = (() => {
       registerInstrumentations({
         instrumentations: [
           new FastifyInstrumentation({
-            requestHook(span, info) {
+            requestHook(span) {
               addOriginToSpan(span, 'auto.http.otel.fastify');
-              updateScopeTransactionName(span, info);
             },
           }),
         ],
@@ -25,22 +22,6 @@ const _fastifyIntegration = (() => {
   };
 }) satisfies IntegrationFn;
 
-function updateScopeTransactionName(span: Span, info: FastifyRequestInfo): void {
-  if (!span.isRecording()) {
-    return;
-  }
-
-  const attributes = spanToJSON(span).data;
-  if (!attributes || !attributes['http.route']) {
-    return;
-  }
-
-  const req = info.request as { method?: string };
-  const method = req.method?.toUpperCase() || 'GET';
-  const route = String(attributes['http.route']);
-  getIsolationScope().setTransactionName(`${method} ${route}`);
-}
-
 /**
  * Express integration
  *
@@ -54,6 +35,19 @@ interface Fastify {
   addHook: (hook: string, handler: (request: unknown, reply: unknown, error: Error) => void) => void;
 }
 
+/**
+ * Minimal request type containing properties around route information.
+ * Works for Fastify 3, 4 and presumably 5.
+ */
+interface FastifyRequestRouteInfo {
+  // since [email protected]
+  routeOptions?: {
+    url?: string;
+    method?: string;
+  };
+  routerPath?: string;
+}
+
 /**
  * Setup an error handler for Fastify.
  */
@@ -64,6 +58,20 @@ export function setupFastifyErrorHandler(fastify: Fastify): void {
         captureException(error);
       });
 
+      // registering `onRequest` hook here instead of using Otel `onRequest` callback b/c `onRequest` hook
+      // is ironically called in the fastify `preHandler` hook which is called later in the lifecycle:
+      // https://fastify.dev/docs/latest/Reference/Lifecycle/
+      fastify.addHook('onRequest', async (request, _reply) => {
+        const reqWithRouteInfo = request as FastifyRequestRouteInfo;
+
+        // Taken from Otel Fastify instrumentation:
+        // https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/plugins/node/opentelemetry-instrumentation-fastify/src/instrumentation.ts#L94-L96
+        const routeName = reqWithRouteInfo.routeOptions?.url || reqWithRouteInfo.routerPath;
+        const method = reqWithRouteInfo.routeOptions?.method || 'GET';
+
+        getIsolationScope().setTransactionName(`${method} ${routeName}`);
+      });
+
       done();
     },
     {