From 411420d94ffa3b891a717bca4ee2ca0525311a61 Mon Sep 17 00:00:00 2001
From: Katie Byers <lobsterkatie@gmail.com>
Date: Thu, 20 May 2021 22:25:21 -0700
Subject: [PATCH] continue transaction from headers

---
 packages/nextjs/src/utils/instrumentServer.ts | 26 ++++++++++++++-----
 packages/node/src/handlers.ts                 |  1 +
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/packages/nextjs/src/utils/instrumentServer.ts b/packages/nextjs/src/utils/instrumentServer.ts
index acdf9af234b5..d1effd5003ee 100644
--- a/packages/nextjs/src/utils/instrumentServer.ts
+++ b/packages/nextjs/src/utils/instrumentServer.ts
@@ -1,7 +1,7 @@
 import { deepReadDirSync } from '@sentry/node';
-import { getActiveTransaction, hasTracingEnabled } from '@sentry/tracing';
+import { extractTraceparentData, getActiveTransaction, hasTracingEnabled } from '@sentry/tracing';
 import { Event as SentryEvent } from '@sentry/types';
-import { fill, logger } from '@sentry/utils';
+import { fill, isString, logger } from '@sentry/utils';
 import * as domain from 'domain';
 import * as http from 'http';
 import { default as createNextServer } from 'next';
@@ -200,6 +200,13 @@ function makeWrappedReqHandler(origReqHandler: ReqHandler): WrappedReqHandler {
 
         // We only want to record page and API requests
         if (hasTracingEnabled() && shouldTraceRequest(req.url, publicDirFiles)) {
+          // If there is a trace header set, extract the data from it (parentSpanId, traceId, and sampling decision)
+          let traceparentData;
+          if (req.headers && isString(req.headers['sentry-trace'])) {
+            traceparentData = extractTraceparentData(req.headers['sentry-trace'] as string);
+            logger.log(`[Tracing] Continuing trace ${traceparentData?.traceId}.`);
+          }
+
           // pull off query string, if any
           const reqPath = req.url.split('?')[0];
 
@@ -207,11 +214,16 @@ function makeWrappedReqHandler(origReqHandler: ReqHandler): WrappedReqHandler {
           // name; requests to API routes could be GET, POST, PUT, etc, so do include it there
           const namePrefix = req.url.startsWith('/api') ? `${(req.method || 'GET').toUpperCase()} ` : '';
 
-          const transaction = Sentry.startTransaction({
-            name: `${namePrefix}${reqPath}`,
-            op: 'http.server',
-            metadata: { requestPath: req.url.split('?')[0] },
-          });
+          const transaction = Sentry.startTransaction(
+            {
+              name: `${namePrefix}${reqPath}`,
+              op: 'http.server',
+              metadata: { requestPath: req.url.split('?')[0] },
+              ...traceparentData,
+            },
+            // extra context passed to the `tracesSampler`
+            { request: req },
+          );
 
           currentScope.setSpan(transaction);
 
diff --git a/packages/node/src/handlers.ts b/packages/node/src/handlers.ts
index 361d16efa0c2..fec2a2846b05 100644
--- a/packages/node/src/handlers.ts
+++ b/packages/node/src/handlers.ts
@@ -65,6 +65,7 @@ export function tracingHandler(): (
         op: 'http.server',
         ...traceparentData,
       },
+      // extra context passed to the tracesSampler
       { request: extractRequestData(req) },
     );