feat(tanstackstart-react): Trace server functions

[nicohrubec]

This PR adds tracing for tss server functions. To achieve this I added a new wrapFetchWithSentry wrapper that can be used to instrument the tss server entry point:

import { wrapFetchWithSentry } from '@sentry/tanstackstart-react';

import handler, { createServerEntry } from '@tanstack/react-start/server-entry';

const requestHandler = wrapFetchWithSentry({
  fetch(request: Request) {
    return handler.fetch(request);
  },
});

export default createServerEntry(requestHandler);

With this we get spans for server functions executed via fetch calls to the server. A limitation of this approach is that out-of-the-box this will only start a single span for the initial request made to the server. So for instance if a server function calls another server function, we will still only get a single span for the outer server function and users would need to wrap the inner call manually.

Screenshot from my sample app with the current state:

Tests added:

• E2E: Basic transaction test to verify that we get spans if a server function is executed.
• E2E: Another transaction test documenting that users need to manually wrap "nested" server functions.
• Unit: Tests to verify the sha256 extraction.

Closes #18287

[github-actions]

size-limit report 📦

⚠️ Warning: Base artifact is not the latest one, because the latest workflow run is not done yet. This may lead to incorrect results. Try to re-run all tests to get up to date results.

Path	Size	% Change	Change
@sentry/browser	24.81 kB	-	-
@sentry/browser - with treeshaking flags	23.3 kB	-	-
@sentry/browser (incl. Tracing)	41.58 kB	-	-
@sentry/browser (incl. Tracing, Profiling)	46.18 kB	-	-
@sentry/browser (incl. Tracing, Replay)	80.16 kB	-	-
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	69.9 kB	-	-
@sentry/browser (incl. Tracing, Replay with Canvas)	84.85 kB	-	-
@sentry/browser (incl. Tracing, Replay, Feedback)	97.08 kB	-	-
@sentry/browser (incl. Feedback)	41.52 kB	-	-
@sentry/browser (incl. sendFeedback)	29.49 kB	-	-
@sentry/browser (incl. FeedbackAsync)	34.48 kB	-	-
@sentry/react	26.52 kB	-	-
@sentry/react (incl. Tracing)	43.78 kB	-	-
@sentry/vue	29.27 kB	-	-
@sentry/vue (incl. Tracing)	43.39 kB	-	-
@sentry/svelte	24.82 kB	-	-
CDN Bundle	27.23 kB	-	-
CDN Bundle (incl. Tracing)	42.22 kB	-	-
CDN Bundle (incl. Tracing, Replay)	78.93 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback)	84.39 kB	-	-
CDN Bundle - uncompressed	80.02 kB	-	-
CDN Bundle (incl. Tracing) - uncompressed	125.37 kB	-	-
CDN Bundle (incl. Tracing, Replay) - uncompressed	241.91 kB	-	-
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	254.67 kB	-	-
@sentry/nextjs (client)	46 kB	-	-
@sentry/sveltekit (client)	41.95 kB	-	-
@sentry/node-core	51.6 kB	-	-
@sentry/node	161.48 kB	-0.01%	-1 B 🔽
@sentry/node - without tracing	93.03 kB	-	-
@sentry/aws-serverless	108.54 kB	-0.01%	-1 B 🔽

View base workflow run

[github-actions]

node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.

Scenario	Requests/s	% of Baseline	Prev. Requests/s	Change %
GET Baseline	8,883	-	8,745	+2%
GET With Sentry	1,794	20%	1,748	+3%
GET With Sentry (error only)	6,204	70%	6,043	+3%
POST Baseline	1,210	-	1,200	+1%
POST With Sentry	611	50%	580	+5%
POST With Sentry (error only)	1,077	89%	1,061	+2%
MYSQL Baseline	3,355	-	3,310	+1%
MYSQL With Sentry	561	17%	457	+23%
MYSQL With Sentry (error only)	2,706	81%	2,676	+1%

View base workflow run

[andreiborza]

LGTM overall, happy to go with this if you decide withSentry is the right api.