feat: transactions in withSentry handler

Author: HazAT

packages/nextjs/src/utils/handlers.ts

@@ -1,7 +1,10 @@
-import { captureException, flush, Handlers, withScope } from '@sentry/node';
-import { addExceptionMechanism } from '@sentry/utils';
+import { captureException, flush, getCurrentHub, Handlers, startTransaction, withScope } from '@sentry/node';
+import { extractTraceparentData, getActiveTransaction, hasTracingEnabled } from '@sentry/tracing';
+import { addExceptionMechanism, isString, logger, stripUrlQueryAndFragment } from '@sentry/utils';
 import { NextApiHandler } from 'next';
 
+import { addRequestDataToEvent, NextRequest } from './instrumentServer';
+
 const { parseRequest } = Handlers;
 
 // purely for clarity
@@ -12,9 +15,43 @@ export const withSentry = (handler: NextApiHandler): WrappedNextApiHandler => {
   // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
   return async (req, res) => {
     try {
-      // TODO: Start Transaction
+      const currentScope = getCurrentHub().getScope();
+
+      if (currentScope) {
+        currentScope.addEventProcessor(event => addRequestDataToEvent(event, req as NextRequest));
+
+        // We only want to record page and API requests
+        if (hasTracingEnabled()) {
+          // 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 ${traceparentData?.traceId}.`);
+          }
+
+          const url = `${req.url}`;
+          // pull off query string, if any
+          const reqPath = stripUrlQueryAndFragment(url);
+
+          // requests for pages will only ever be GET requests, so don't bother to include the method in the transaction
+          // name; requests to API routes could be GET, POST, PUT, etc, so do include it there
+          const namePrefix = `${(req.method || 'GET').toUpperCase()} `;
+
+          const transaction = startTransaction(
+            {
+              name: `${namePrefix}${reqPath}`,
+              op: 'http.server',
+              metadata: { requestPath: reqPath },
+              ...traceparentData,
+            },
+            // extra context passed to the `tracesSampler`
+            { request: req },
+          );
+          currentScope.setSpan(transaction);
+        }
+      }
+
       return await handler(req, res); // Call Handler
-      // TODO: Finish Transaction
     } catch (e) {
       withScope(scope => {
         scope.addEventProcessor(event => {
@@ -27,6 +64,17 @@ export const withSentry = (handler: NextApiHandler): WrappedNextApiHandler => {
       });
       throw e;
     } finally {
+      const transaction = getActiveTransaction();
+      if (transaction) {
+        transaction.setHttpStatus(res.statusCode);
+
+        // we'll collect this data in a more targeted way in the event processor we added above,
+        // `addRequestDataToEvent`
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+        delete transaction.metadata.requestPath;
+
+        transaction.finish();
+      }
       await flush(2000);
     }
   };