read tracestate data from incoming node requests

Author: lobsterkatie

packages/node/src/handlers.ts

@@ -1,7 +1,7 @@
 /* eslint-disable max-lines */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import { captureException, getCurrentHub, startTransaction, withScope } from '@sentry/core';
-import { extractSentrytraceData, Span } from '@sentry/tracing';
+import { extractSentrytraceData, extractTracestateData, Span } from '@sentry/tracing';
 import { Event, ExtractedNodeRequestData, Transaction } from '@sentry/types';
 import { forget, isPlainObject, isString, logger, normalize, stripUrlQueryAndFragment } from '@sentry/utils';
 import * as cookie from 'cookie';
@@ -55,17 +55,21 @@ export function tracingHandler(): (
     res: http.ServerResponse,
     next: (error?: any) => void,
   ): void {
-    // If there is a trace header set, we extract the data from it (parentSpanId, traceId, and sampling decision)
-    let traceparentData;
-    if (req.headers && isString(req.headers['sentry-trace'])) {
+    // Extract data from trace headers
+    let traceparentData, tracestateData;
+    if (req.headers?.['sentry-trace']) {
       traceparentData = extractSentrytraceData(req.headers['sentry-trace'] as string);
     }
+    if (req.headers?.tracestate) {
+      tracestateData = extractTracestateData(req.headers.tracestate as string);
+    }
 
     const transaction = startTransaction(
       {
         name: extractExpressTransactionName(req, { path: true, method: true }),
         op: 'http.server',
         ...traceparentData,
+        metadata: { tracestate: tracestateData },
       },
       { request: extractRequestData(req) },
     );

packages/node/test/handlers.test.ts

@@ -221,8 +221,11 @@ describe('tracingHandler', () => {
     expect(startTransaction).toHaveBeenCalled();
   });
 
-  it("pulls parent's data from tracing header on the request", () => {
-    req.headers = { 'sentry-trace': '12312012123120121231201212312012-1121201211212012-0' };
+  it('pulls data from tracing headers on the request', () => {
+    req.headers = {
+      'sentry-trace': '12312012123120121231201212312012-1121201211212012-0',
+      tracestate: 'sentry=doGsaREgReaT',
+    };
 
     sentryTracingMiddleware(req, res, next);
 
@@ -232,6 +235,7 @@ describe('tracingHandler', () => {
     expect(transaction.traceId).toEqual('12312012123120121231201212312012');
     expect(transaction.parentSpanId).toEqual('1121201211212012');
     expect(transaction.sampled).toEqual(false);
+    expect(transaction.metadata?.tracestate).toEqual({ sentry: 'sentry=doGsaREgReaT' });
   });
 
   it('extracts request data for sampling context', () => {