fix(node): Add conditions to TracingHandler.startTransaction

packages/node/src/handlers.ts

@@ -33,6 +33,24 @@ export function tracingHandler(): (
     res: http.ServerResponse,
     next: (error?: any) => void,
   ): void {
+    const hub = getCurrentHub();
+    const options = hub.getClient()?.getOptions();
+
+    if (!options || req.method?.toUpperCase() === 'OPTIONS' || req.method?.toUpperCase() === 'HEAD') {
+      return next();
+    }
+
+    // TODO: This is the `hasTracingEnabled` check, but we're doing it manually since `@sentry/tracing` isn't a
+    // dependency of `@sentry/node`. Long term, that function should probably move to `@sentry/hub.
+    if (!('tracesSampleRate' in options) && !('tracesSampler' in options)) {
+      __DEBUG_BUILD__ &&
+        logger.warn(
+          'Sentry `tracingHandler` is being used, but tracing is disabled. Please enable tracing by setting ' +
+            'either `tracesSampleRate` or `tracesSampler` in your `Sentry.init()` options.',
+        );
+      return next();
+    }
+
     // If there is a trace header set, we extract the data from it (parentSpanId, traceId, and sampling decision)
     const traceparentData =
       req.headers && isString(req.headers['sentry-trace']) && extractTraceparentData(req.headers['sentry-trace']);
@@ -53,7 +71,7 @@ export function tracingHandler(): (
     );
 
     // We put the transaction on the scope so users can attach children to it
-    getCurrentHub().configureScope(scope => {
+    hub.configureScope(scope => {
       scope.setSpan(transaction);
     });
 

packages/node/test/handlers.test.ts

@@ -150,14 +150,16 @@ describe('tracingHandler', () => {
 
   const sentryTracingMiddleware = tracingHandler();
 
-  let req: http.IncomingMessage, res: http.ServerResponse, next: () => undefined;
+  let hub: Hub, req: http.IncomingMessage, res: http.ServerResponse, next: () => undefined;
 
   function createNoOpSpy() {
     const noop = { noop: () => undefined }; // this is wrapped in an object so jest can spy on it
     return jest.spyOn(noop, 'noop') as any;
   }
 
   beforeEach(() => {
+    hub = new Hub(new NodeClient(getDefaultNodeClientOptions({ tracesSampleRate: 1.0 })));
+    jest.spyOn(sentryCore, 'getCurrentHub').mockReturnValue(hub);
     req = {
       headers,
       method,
@@ -181,6 +183,33 @@ describe('tracingHandler', () => {
     expect(startTransaction).toHaveBeenCalled();
   });
 
+  it("doesn't create a transaction when handling a `HEAD` request", () => {
+    const startTransaction = jest.spyOn(sentryCore, 'startTransaction');
+    req.method = 'HEAD';
+
+    sentryTracingMiddleware(req, res, next);
+
+    expect(startTransaction).not.toHaveBeenCalled();
+  });
+
+  it("doesn't create a transaction when handling an `OPTIONS` request", () => {
+    const startTransaction = jest.spyOn(sentryCore, 'startTransaction');
+    req.method = 'OPTIONS';
+
+    sentryTracingMiddleware(req, res, next);
+
+    expect(startTransaction).not.toHaveBeenCalled();
+  });
+
+  it("doesn't create a transaction if tracing is disabled", () => {
+    delete hub.getClient()?.getOptions().tracesSampleRate;
+    const startTransaction = jest.spyOn(sentryCore, 'startTransaction');
+
+    sentryTracingMiddleware(req, res, next);
+
+    expect(startTransaction).not.toHaveBeenCalled();
+  });
+
   it("pulls parent's data from tracing header on the request", () => {
     req.headers = { 'sentry-trace': '12312012123120121231201212312012-1121201211212012-0' };