feat: Initial tracing setup (peer deps + utils) #13899

elliott-with-the-longest-name-on-github · 2025-06-17T21:15:26Z

Adds spans to load (on the server), server actions, and handle/resolve. It also adds a tracing object with enabled, root, and current to the RequestEvent, ServerLoadEvent, and LoadEvent types. This means you can get access to a span to annotate it pretty much anywhere -- including using getRequestEvent (this could be quite nice for library integrations!).

We're punting on clientside tracing for now, as we do not feel the o11y community has sufficiently converged on approaches (see https://github.com/open-telemetry/community/blob/main/projects/browser-phase-1.md). When OTEL provides a stable and truly browser-native tracing platform, we'll be all over it.

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elliott-with-the-longest-name-on-github · 2025-06-17T21:15:44Z

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changeset-bot · 2025-06-18T22:46:29Z

🦋 Changeset detected

Latest commit: 4b64316

The changes in this PR will be included in the next version bump.

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@sveltejs/kit	Minor

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andreiborza

This looks good to me. As discussed on Slack, it might be nice if users had the ability to modify the root span (e.g. via a requestHook).

Lms24

Nice! Thanks a lot for adding this!

Just had a minor concern about performance of dynamically importing @opentelemetry/api multiple times but I think overall, the implementation is great!

packages/kit/src/runtime/telemetry/get_tracer.spec.js

packages/kit/src/runtime/telemetry/record_span.js

Lms24 · 2025-07-09T10:11:07Z

packages/kit/src/runtime/telemetry/record_span.js

+				span.recordException({
+					name: 'HttpError',
+					message: error.body.message
+				});


does a HttpError also have a stack? If so, would be cool to also record the stack trace.

Furthermore, I'm not 100% sure if this applies here but in our SDK, when we capture HttpErrors, we ignore 4xx errors because usually you don't want to record exceptions for bad requests, 404s, etc. Might be worth a thought if they are valuable or too noisy but happy to leave the call up to you!

https://github.com/getsentry/sentry-javascript/blob/8beaa4ea602d3517c272f07b8546325059bcfc21/packages/sveltekit/src/client/load.ts#L23-L38

Yeah, lemme think about this one -- not sure if we should just exclude all 400s or give users the ability to filter status codes. My initial feeling is just exclude 400s and see if anyone ever asks for the ability to see them

~~We should probably share the logic contained in #13848~~

Don't think I agree -- this is just about setting the status of the span, not whether we capture the span at all. I adjusted the logic to only set an error status on >=500; otherwise it's captured as a normal span

svelte-docs-bot · 2025-07-16T23:09:20Z

Preview: https://svelte-dev-git-preview-kit-13899-svelte.vercel.app/

…13900) * feat: Add tracing to `load`, server actions, and `handle`/`resolve` * feat: add universal IDs to client nodes * approve otp dep build * add links for docs * since tags * clarify * explain util * import the rest of the types through jsdoc import statements * generate types --------- Co-authored-by: Chew Tee Ming <chew.tee.ming@nindatech.com>

eltigerchino · 2025-07-23T08:10:55Z

Thanks! This looks good. I think all we need is a changeset and some documentation on how to get started. The instructions could be similar to the setup in the demo of #13900 (comment) or we might want to try and get something like #13776 merged next

cc: @manuel3108 @AdrianGonz97 would we want to add some kind of OpenTelemetry or Sentry add-on to the Svelte CLI in the future to make the setup more seamless?

Rich-Harris

nice! mostly looks good but I think we can avoid passing tracer around etc

packages/kit/src/core/config/options.js

Rich-Harris · 2025-07-23T12:16:37Z

packages/kit/src/exports/public.d.ts

+		/**
+		 * Whether to enable server-side [OpenTelemetry](https://opentelemetry.io/) tracing for SvelteKit operations including the [`handle` hook](https://svelte.dev/docs/kit/hooks#Server-hooks-handle), [`load` functions](https://svelte.dev/docs/kit/load), and [form actions](https://svelte.dev/docs/kit/form-actions).
+		 * @default undefined
+		 * @since 2.26.0 // TODO: update this before publishing


Rich-Harris · 2025-07-23T12:16:58Z

packages/kit/src/exports/public.d.ts

+
+	/**
+	 * Access to spans for tracing. If tracing is not enabled or the function is being run in the browser, these spans will do nothing.\
+	 * @since 2.26.0 // TODO: update this before publishing


packages/kit/src/exports/public.d.ts

packages/kit/src/runtime/server/page/actions.js

packages/kit/test/apps/basics/test/server.test.js

packages/kit/test/utils.js

packages/kit/src/runtime/telemetry/record_span.js

Co-authored-by: Rich Harris <richard.a.harris@gmail.com>

elliott-with-the-longest-name-on-github · 2025-07-24T17:28:36Z

packages/kit/src/exports/public.d.ts

+
+	/**
+	 * Access to spans for tracing. If tracing is not enabled, these spans will do nothing.
+	 * @since 2.26.0 // TODO: update this before publishing


Rich-Harris

beautiful 😍

Rich-Harris · 2025-07-24T20:51:08Z

nervous about that test failure, not sure why that's happening suddenly

Rich-Harris

rescinding my earlier approval because i was reminded that this should probably have some docs

elliott-with-the-longest-name-on-github mentioned this pull request Jun 17, 2025

feat: add universal IDs to client nodes #13898

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elliott-with-the-longest-name-on-github mentioned this pull request Jun 17, 2025

feat: Add tracing to load, server actions, and handle/resolve #13900

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elliott-with-the-longest-name-on-github marked this pull request as ready for review June 17, 2025 21:17

elliott-with-the-longest-name-on-github marked this pull request as draft June 18, 2025 19:42

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andreiborza approved these changes Jul 7, 2025

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feat: Initial tracing setup (peer deps + utils)

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elliott-with-the-longest-name-on-github marked this pull request as ready for review July 17, 2025 04:01

Merge branch 'main' into elliott/init-tracing

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eltigerchino added the feature / enhancement New feature or request label Jul 23, 2025

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elliott-with-the-longest-name-on-github and others added 3 commits July 23, 2025 10:46

Update packages/kit/src/exports/public.d.ts

f65b78f

Co-authored-by: Rich Harris <richard.a.harris@gmail.com>

chore: Switch to tracing: { server: boolean }

77d447f

chore: Make enablement / importing of otel make more sense

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elliott-with-the-longest-name-on-github and others added 8 commits July 23, 2025 17:48

chore: merge_tracing function

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fix rich's bad comment that shouldn't have ever existed >:(

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test stuff

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Update packages/kit/test/utils.js

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Co-authored-by: Rich Harris <richard.a.harris@gmail.com>

i am truly among the dumbest

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Merge branch 'main' into elliott/init-tracing

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types

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elliott-with-the-longest-name-on-github added 3 commits July 24, 2025 11:51

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fix dumb import analysis

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