fix: carry the tracing span in the request store instead of copying the event

.changeset/olive-donkeys-relax.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: keep one request event identity across `handle`, `load` and `handleFetch`

packages/kit/src/exports/hooks/sequence.js

@@ -1,9 +1,5 @@
 /** @import { Handle, RequestEvent, ResolveOptions } from '@sveltejs/kit' */
-import {
-	merge_tracing,
-	get_request_store,
-	with_request_store
-} from '@sveltejs/kit/internal/server';
+import { get_request_store, with_request_store } from '@sveltejs/kit/internal/server';
 
 /**
  * A helper function for sequencing multiple `handle` calls in a middleware-like manner.
@@ -98,11 +94,10 @@ export function sequence(...handlers) {
 			return state.tracing.record_span({
 				name: `sveltekit.handle.sequenced.${handle.name ? handle.name : i}`,
 				attributes: {},
-				fn: async (current) => {
-					const traced_event = merge_tracing(event, current);
-					return await with_request_store({ event: traced_event, state }, () =>
+				fn: async () =>
+					with_request_store({ event, state }, () =>
 						handle({
-							event: traced_event,
+							event,
 							resolve: (event, options) => {
 								/** @type {ResolveOptions['transformPageChunk']} */
 								const transformPageChunk = async ({ html, done }) => {
@@ -138,8 +133,7 @@ export function sequence(...handlers) {
 										});
 							}
 						})
-					);
-				}
+					)
 			});
 		}
 	};

packages/kit/src/exports/internal/server/index.js

@@ -1,4 +1,3 @@
-/** @import { Span } from '@opentelemetry/api' */
 import { try_get_request_store } from './event.js';
 
 export function get_origin() {
@@ -7,22 +6,6 @@ export function get_origin() {
 	return request && new URL(request.url).origin;
 }
 
-/**
- * @template {{ tracing: { enabled: boolean, root: Span, current: Span } }} T
- * @param {T} event_like
- * @param {Span} current
- * @returns {T}
- */
-export function merge_tracing(event_like, current) {
-	return {
-		...event_like,
-		tracing: {
-			...event_like.tracing,
-			current
-		}
-	};
-}
-
 export {
 	with_request_store,
 	getRequestEvent,

packages/kit/src/runtime/server/data/index.js

@@ -5,7 +5,6 @@ import { once } from '../../../utils/functions.js';
 import { server_data_serializer_json } from '../page/data_serializer.js';
 import { load_server_data } from '../page/load_data.js';
 import { handle_error_and_jsonify } from '../errors.js';
-import { normalize_path } from '../../../utils/url.js';
 import { text_encoder } from '../../utils.js';
 import { with_version_header } from '../utils.js';
 
@@ -17,7 +16,6 @@ import { with_version_header } from '../utils.js';
  * @param {import('@sveltejs/kit').SSRManifest} manifest
  * @param {import('types').SSRState} state
  * @param {boolean[] | undefined} invalidated_data_nodes
- * @param {import('types').TrailingSlash} trailing_slash
  * @returns {Promise<Response>}
  */
 export async function render_data(
@@ -27,8 +25,7 @@ export async function render_data(
 	options,
 	manifest,
 	state,
-	invalidated_data_nodes,
-	trailing_slash
+	invalidated_data_nodes
 ) {
 	if (!route.page) {
 		// requesting /__data.json should fail for a +server.js
@@ -41,11 +38,6 @@ export async function render_data(
 
 		let aborted = false;
 
-		const url = new URL(event.url);
-		url.pathname = normalize_path(url.pathname, trailing_slash);
-
-		const new_event = { ...event, url };
-
 		const functions = node_ids.map((n, i) => {
 			return once(async () => {
 				try {
@@ -59,7 +51,7 @@ export async function render_data(
 					const node = n == undefined ? n : await manifest._.nodes[n]();
 					// load this. for the child, return as is. for the final result, stream things
 					return load_server_data({
-						event: new_event,
+						event,
 						event_state,
 						state,
 						node,

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

@@ -4,7 +4,7 @@ import * as devalue from 'devalue';
 import { DEV } from 'esm-env';
 import { json } from '@sveltejs/kit';
 import { HttpError, Redirect, ActionFailure, SvelteKitError } from '@sveltejs/kit/internal';
-import { with_request_store, merge_tracing } from '@sveltejs/kit/internal/server';
+import { with_request_store } from '@sveltejs/kit/internal/server';
 import { normalize_error } from '../../../utils/error.js';
 import { is_form_content_type, negotiate } from '../../../utils/http.js';
 import { create_replacer, with_version_header } from '../utils.js';
@@ -281,11 +281,7 @@ async function call_action(event, event_state, actions) {
 			'http.route': event.route.id || 'unknown'
 		},
 		fn: async (current) => {
-			const traced_event = merge_tracing(event, current);
-
-			const result = await with_request_store({ event: traced_event, state: event_state }, () =>
-				action(traced_event)
-			);
+			const result = await with_request_store({ event, state: event_state }, () => action(event));
 
 			if (result instanceof ActionFailure) {
 				current.setAttributes({

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

@@ -2,7 +2,7 @@ import { DEV } from 'esm-env';
 import { noop } from '../../../utils/functions.js';
 import { disable_search, make_trackable } from '../../../utils/url.js';
 import { validate_depends, validate_load_response } from '../../shared.js';
-import { with_request_store, merge_tracing } from '@sveltejs/kit/internal/server';
+import { with_request_store } from '@sveltejs/kit/internal/server';
 import { record_span } from '../../telemetry/record_span.js';
 import { base64_encode } from '../../utils.js';
 import { NULL_BODY_STATUS } from '../constants.js';
@@ -81,11 +81,10 @@ export async function load_server_data({ event, event_state, state, node, parent
 			'sveltekit.load.environment': 'server',
 			'http.route': event.route.id || 'unknown'
 		},
-		fn: async (current) => {
-			const traced_event = merge_tracing(event, current);
-			const result = await with_request_store({ event: traced_event, state: event_state }, () =>
+		fn: async () =>
+			with_request_store({ event, state: event_state }, () =>
 				load.call(null, {
-					...traced_event,
+					...event,
 					fetch: (info, init) => {
 						const url = new URL(info instanceof Request ? info.url : info, event.url);
 
@@ -170,10 +169,7 @@ export async function load_server_data({ event, event_state, state, node, parent
 						}
 					}
 				})
-			);
-
-			return result;
-		}
+			)
 	});
 
 	if (DEV) {
@@ -232,11 +228,10 @@ export async function load_data({
 			'sveltekit.load.environment': 'server',
 			'http.route': event.route.id || 'unknown'
 		},
-		fn: async (current) => {
-			const traced_event = merge_tracing(event, current);
+		fn: async () => {
 			const child_state = { ...event_state, is_in_universal_load: true };
 
-			return await with_request_store({ event: traced_event, state: child_state }, () =>
+			return await with_request_store({ event, state: child_state }, () =>
 				load.call(null, {
 					url: event.url,
 					params: event.params,
@@ -247,7 +242,7 @@ export async function load_data({
 					depends: noop,
 					parent,
 					untrack: (fn) => fn(),
-					tracing: traced_event.tracing
+					tracing: event.tracing
 				})
 			);
 		}

packages/kit/src/runtime/server/remote-functions.js

@@ -3,7 +3,7 @@
 
 import { json, error } from '@sveltejs/kit';
 import { Redirect, SvelteKitError } from '@sveltejs/kit/internal';
-import { with_request_store, merge_tracing } from '@sveltejs/kit/internal/server';
+import { with_request_store } from '@sveltejs/kit/internal/server';
 import { app_dir, base } from '$app/paths/internal/server';
 import { is_form_content_type } from '../../utils/http.js';
 import { create_remote_key, parse_remote_arg, split_remote_key, stringify } from '../shared.js';
@@ -29,10 +29,9 @@ export async function handle_remote_call(event, state, options, manifest, id) {
 		attributes: {
 			'sveltekit.remote.call.id': id
 		},
-		fn: async (current) => {
-			const traced_event = merge_tracing(event, current);
-			const response = await with_request_store({ event: traced_event, state }, () =>
-				handle_remote_call_internal(traced_event, state, options, manifest, id)
+		fn: async () => {
+			const response = await with_request_store({ event, state }, () =>
+				handle_remote_call_internal(event, state, options, manifest, id)
 			);
 			return with_version_header(response);
 		}
@@ -520,12 +519,10 @@ export async function handle_remote_form_post(event, state, manifest, id) {
 		attributes: {
 			'sveltekit.remote.form.post.id': id
 		},
-		fn: (current) => {
-			const traced_event = merge_tracing(event, current);
-			return with_request_store({ event: traced_event, state }, () =>
-				handle_remote_form_post_internal(traced_event, state, manifest, id)
-			);
-		}
+		fn: () =>
+			with_request_store({ event, state }, () =>
+				handle_remote_form_post_internal(event, state, manifest, id)
+			)
 	});
 }
 

packages/kit/src/runtime/server/respond.js

@@ -2,7 +2,7 @@
 import { DEV } from 'esm-env';
 import { json, text } from '@sveltejs/kit';
 import { Redirect, SvelteKitError } from '@sveltejs/kit/internal';
-import { merge_tracing, with_request_store } from '@sveltejs/kit/internal/server';
+import { with_request_store } from '@sveltejs/kit/internal/server';
 import { base, app_dir } from '$app/paths/internal/server';
 import { is_endpoint_request, render_endpoint } from './endpoint.js';
 import { render_page } from './page/index.js';
@@ -39,7 +39,7 @@ import {
 import { server_data_serializer } from './page/data_serializer.js';
 import { get_remote_id, handle_remote_call } from './remote-functions.js';
 import { record_span } from '../telemetry/record_span.js';
-import { otel } from '../telemetry/otel.js';
+import { otel, trace } from '../telemetry/otel.js';
 
 /** @type {import('types').RequiredResolveOptions['transformPageChunk']} */
 const default_transform = ({ html }) => html;
@@ -204,6 +204,8 @@ export async function internal_respond(request, options, manifest, state) {
 		cookies,
 		// @ts-expect-error `fetch` needs to be created after the `event` itself
 		fetch: null,
+		// @ts-expect-error `tracing` needs the root span, which is created during `handle`
+		tracing: null,
 		getClientAddress:
 			state.getClientAddress ||
 			(() => {
@@ -421,6 +423,9 @@ export async function internal_respond(request, options, manifest, state) {
 						}
 					});
 				}
+			} else {
+				// a data request can't follow a redirect, so normalize the path in place
+				url.pathname = normalize_path(url.pathname, trailing_slash);
 			}
 
 			if (state.before_handle || state.emulator?.platform) {
@@ -484,18 +489,17 @@ export async function internal_respond(request, options, manifest, state) {
 				'sveltekit.is_sub_request': event.isSubRequest
 			},
 			fn: async (root_span) => {
-				const traced_event = {
-					...event,
-					tracing: {
-						enabled: __SVELTEKIT_SERVER_TRACING_ENABLED__,
-						root: root_span,
-						current: root_span
+				event.tracing = {
+					enabled: __SVELTEKIT_SERVER_TRACING_ENABLED__,
+					root: root_span,
+					get current() {
+						return trace?.getActiveSpan() ?? root_span;
 					}
 				};
 
-				return await with_request_store({ event: traced_event, state: event_state }, () =>
+				return await with_request_store({ event, state: event_state }, () =>
 					options.hooks.handle({
-						event: traced_event,
+						event,
 						resolve: (event, opts) => {
 							return record_span({
 								name: 'sveltekit.resolve',
@@ -506,30 +510,28 @@ export async function internal_respond(request, options, manifest, state) {
 									// counter-intuitively, we need to clear the event, so that it's not
 									// e.g. accessible when loading modules needed to handle the request
 									return with_request_store(null, () =>
-										resolve(merge_tracing(event, resolve_span), page_nodes, opts).then(
-											(response) => {
-												// add headers/cookies here, rather than inside `resolve`, so that we
-												// can do it once for all responses instead of once per `return`
-												for (const key in headers) {
-													const value = headers[key];
-													response.headers.set(key, /** @type {string} */ (value));
-												}
-
-												add_cookies_to_headers(response.headers, new_cookies.values());
-
-												if (state.prerendering && event.route.id !== null) {
-													response.headers.set('x-sveltekit-routeid', encodeURI(event.route.id));
-												}
-
-												resolve_span.setAttributes({
-													'http.response.status_code': response.status,
-													'http.response.body.size':
-														response.headers.get('content-length') || 'unknown'
-												});
-
-												return response;
+										resolve(event, page_nodes, opts).then((response) => {
+											// add headers/cookies here, rather than inside `resolve`, so that we
+											// can do it once for all responses instead of once per `return`
+											for (const key in headers) {
+												const value = headers[key];
+												response.headers.set(key, /** @type {string} */ (value));
+											}
+
+											add_cookies_to_headers(response.headers, new_cookies.values());
+
+											if (state.prerendering && event.route.id !== null) {
+												response.headers.set('x-sveltekit-routeid', encodeURI(event.route.id));
 											}
-										)
+
+											resolve_span.setAttributes({
+												'http.response.status_code': response.status,
+												'http.response.body.size':
+													response.headers.get('content-length') || 'unknown'
+											});
+
+											return response;
+										})
 									);
 								}
 							});
@@ -655,8 +657,7 @@ export async function internal_respond(request, options, manifest, state) {
 						options,
 						manifest,
 						state,
-						invalidated_data_nodes,
-						trailing_slash
+						invalidated_data_nodes
 					);
 				} else {
 					let endpoint;

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

@@ -1,11 +1,19 @@
-/** @import { Tracer, SpanStatusCode, PropagationAPI, ContextAPI } from '@opentelemetry/api' */
+/** @import { Tracer, SpanStatusCode, PropagationAPI, ContextAPI, TraceAPI } from '@opentelemetry/api' */
 
 /** @type {Promise<{ tracer: Tracer, SpanStatusCode: typeof SpanStatusCode, propagation: PropagationAPI, context: ContextAPI }> | null} */
 export let otel = null;
 
+/**
+ * Synchronously readable once `otel` has resolved, which is guaranteed
+ * before any span exists — `record_span` awaits `otel` first.
+ * @type {TraceAPI | null}
+ */
+export let trace = null;
+
 if (__SVELTEKIT_SERVER_TRACING_ENABLED__) {
 	otel = import('@opentelemetry/api')
 		.then((module) => {
+			trace = module.trace;
 			return {
 				tracer: module.trace.getTracer('sveltekit'),
 				propagation: module.propagation,