fix(v10/sveltekit): Read SvelteKit config from the Vite plugin

Backport of: #23678

Author: chargome

packages/sveltekit/src/vite/autoInstrument.ts

@@ -4,7 +4,8 @@ import * as fs from 'fs';
 import * as path from 'path';
 import type { Plugin } from 'vite';
 import { WRAPPED_MODULE_SUFFIX } from '../common/utils';
-import type { BackwardsForwardsCompatibleKitConfig, BackwardsForwardsCompatibleSvelteConfig } from './svelteConfig';
+import type { ResolvedKitConfig } from './kitConfig';
+import { isNativeServerTracingEnabled } from './kitConfig';
 
 const AcornParser = acorn.Parser.extend(tsPlugin());
 
@@ -29,7 +30,7 @@ export type AutoInstrumentSelection = {
 
 type AutoInstrumentPluginOptions = AutoInstrumentSelection & {
   debug: boolean;
-  onlyInstrumentClient: boolean;
+  getKitConfig: () => Promise<ResolvedKitConfig>;
 };
 
 /**
@@ -42,14 +43,15 @@ type AutoInstrumentPluginOptions = AutoInstrumentSelection & {
  * @returns the plugin
  */
 export function makeAutoInstrumentationPlugin(options: AutoInstrumentPluginOptions): Plugin {
-  const { load: wrapLoadEnabled, serverLoad: wrapServerLoadEnabled, debug } = options;
+  const { load: wrapLoadEnabled, serverLoad: wrapServerLoadEnabled, debug, getKitConfig } = options;
 
   let isServerBuild: boolean | undefined = undefined;
 
   // Whether we should skip server-side load instrumentation because SvelteKit's native server
-  // tracing is enabled. Initialized from the option (derived from `svelte.config.js`), but may be
-  // flipped to `true` in `configResolved` once we can read SvelteKit's resolved config (see below).
-  let onlyInstrumentClient = options.onlyInstrumentClient;
+  // tracing is enabled. If it is, adding our own wrapper on top would emit duplicate spans.
+  let onlyInstrumentClientPromise: Promise<boolean> | undefined;
+  const shouldOnlyInstrumentClient = (): Promise<boolean> =>
+    (onlyInstrumentClientPromise ??= getKitConfig().then(isNativeServerTracingEnabled));
 
   return {
     name: 'sentry-auto-instrumentation',
@@ -62,16 +64,6 @@ export function makeAutoInstrumentationPlugin(options: AutoInstrumentPluginOptio
       // `config.build.ssr` is `true` for that first build and `false` in the other ones.
       // Hence we can use it as a switch to upload source maps only once in main build.
       isServerBuild = !!config.build.ssr;
-
-      // As of SvelteKit 3, the native server-tracing config is no longer read from
-      // `svelte.config.js` (so the `onlyInstrumentClient` option, derived from it, is `false`).
-      // It's passed to the `sveltekit()` Vite plugin instead, which exposes the resolved config
-      // via its plugin `api.options`. Reading it here lets us reliably detect native tracing
-      // regardless of SvelteKit version. When it's enabled, we must not add our own server-side
-      // load instrumentation, otherwise we'd emit duplicate spans on top of SvelteKit's.
-      if (!onlyInstrumentClient && isNativeServerTracingEnabled(config.plugins)) {
-        onlyInstrumentClient = true;
-      }
     },
 
     async load(id) {
@@ -81,7 +73,7 @@ export function makeAutoInstrumentationPlugin(options: AutoInstrumentPluginOptio
       const environmentName = (this as { environment?: { name?: string } }).environment?.name;
       const isServerEnvironment = environmentName != null ? environmentName === 'ssr' : !!isServerBuild;
 
-      if (onlyInstrumentClient && isServerEnvironment) {
+      if (isServerEnvironment && (await shouldOnlyInstrumentClient())) {
         return null;
       }
 
@@ -96,9 +88,9 @@ export function makeAutoInstrumentationPlugin(options: AutoInstrumentPluginOptio
         return getWrapperCode('wrapLoadWithSentry', `${id}${WRAPPED_MODULE_SUFFIX}`);
       }
 
-      if (onlyInstrumentClient) {
+      if (await shouldOnlyInstrumentClient()) {
         // Now that we've checked universal files, we can early return and avoid further
-        // regexp checks below for server-only files, in case `onlyInstrumentClient` is `true`.
+        // regexp checks below for server-only files.
         return null;
       }
 
@@ -118,39 +110,6 @@ export function makeAutoInstrumentationPlugin(options: AutoInstrumentPluginOptio
   };
 }
 
-/**
- * Detects whether SvelteKit's native server-side tracing is enabled by reading the resolved
- * SvelteKit config that the `sveltekit()` Vite plugin exposes via its plugin `api.options`.
- *
- * This is the source of truth as of SvelteKit 3, where the config moved out of `svelte.config.js`
- * and into the `sveltekit()` plugin. On older SvelteKit versions that don't expose the config this
- * way, it simply returns `false` and we fall back to the `svelte.config.js`-derived value.
- */
-function isNativeServerTracingEnabled(plugins: readonly Plugin[] | undefined): boolean {
-  if (!plugins) {
-    return false;
-  }
-
-  for (const plugin of plugins) {
-    const options = (
-      plugin?.api as
-        | { options?: BackwardsForwardsCompatibleSvelteConfig & BackwardsForwardsCompatibleKitConfig }
-        | undefined
-    )?.options;
-
-    // SvelteKit 3 flattened the plugin config: what used to live under `kit` now sits
-    // at the top level of the exposed options.
-    const kitConfig = options?.kit ?? options;
-
-    // SvelteKit 3 promoted `tracing` out of `experimental`; older versions nest it there.
-    if (kitConfig?.tracing?.server || kitConfig?.experimental?.tracing?.server) {
-      return true;
-    }
-  }
-
-  return false;
-}
-
 /**
  * We only want to apply our wrapper to files that
  *

packages/sveltekit/src/vite/detectAdapter.ts

@@ -1,7 +1,7 @@
 import type { Package } from '@sentry/core';
 import * as fs from 'fs';
 import * as path from 'path';
-import type { BackwardsForwardsCompatibleSvelteConfig } from './svelteConfig';
+import type { ResolvedKitConfig } from './kitConfig';
 
 /**
  * Supported @sveltejs/adapters-[adapter] SvelteKit adapters
@@ -21,33 +21,33 @@ const ADAPTER_NAME_MAP: Record<string, SupportedSvelteKitAdapters> = {
 
 /**
  * Tries to detect the used adapter for SvelteKit.
- * 1. If svelteConfig is provided and has kit.adapter.name, uses that (source of truth from svelte.config.js).
+ * 1. If kitConfig is provided and has adapter.name, uses that (source of truth from SvelteKit itself).
  * 2. Otherwise falls back to inferring from package.json dependencies.
  * Returns the name of the adapter or 'other' if no supported adapter was found.
  *
- * @param svelteConfig - Loaded svelte config (e.g. from loadSvelteConfig()). Pass `undefined` to skip config-based detection.
+ * @param kitConfig - Resolved SvelteKit config (e.g. from the kit config resolver). Pass `undefined` to skip config-based detection.
  * @param debug - Whether to log detection result. Pass `undefined` for false.
  */
 export async function detectAdapter(
-  svelteConfig: BackwardsForwardsCompatibleSvelteConfig | undefined,
+  kitConfig: ResolvedKitConfig | undefined,
   debug: boolean | undefined,
 ): Promise<SupportedSvelteKitAdapters> {
-  const adapterName = svelteConfig?.kit?.adapter?.name;
+  const adapterName = kitConfig?.adapter?.name;
   if (adapterName && typeof adapterName === 'string') {
     const mapped = ADAPTER_NAME_MAP[adapterName];
     if (mapped) {
       if (debug) {
         // eslint-disable-next-line no-console
-        console.log(`[Sentry SvelteKit Plugin] Detected SvelteKit ${mapped} adapter from \`svelte.config.js\``);
+        console.log(`[Sentry SvelteKit Plugin] Detected SvelteKit ${mapped} adapter from your SvelteKit config`);
       }
       return mapped;
     }
     // We found an adapter name but it's not in our supported list -> return 'other'
-    // svelte.config.js is the source of truth, so we don't need to fall back to package.json.
+    // The SvelteKit config is the source of truth, so we don't need to fall back to package.json.
     if (debug) {
       // eslint-disable-next-line no-console
       console.warn(
-        `[Sentry SvelteKit Plugin] Detected unsupported adapter name ${adapterName} in \`svelte.config.js\`. Please set the 'adapter' option manually`,
+        `[Sentry SvelteKit Plugin] Detected unsupported adapter name ${adapterName} in your SvelteKit config. Please set the 'adapter' option manually`,
       );
     }
     return 'other';

packages/sveltekit/src/vite/injectGlobalValues.ts

@@ -1,8 +1,8 @@
 import { escapeStringForRegex, type InternalGlobal } from '@sentry/core';
 import MagicString from 'magic-string';
 import type { Plugin } from 'vite';
-import { type BackwardsForwardsCompatibleSvelteConfig, getAdapterOutputDir, getHooksFileName } from './svelteConfig';
-import type { SentrySvelteKitPluginOptions } from './types';
+import type { ResolvedKitConfig } from './kitConfig';
+import { getHooksFileName } from './svelteConfig';
 
 export type GlobalSentryValues = {
   __sentry_sveltekit_output_dir?: string;
@@ -32,33 +32,55 @@ export function getGlobalValueInjectionCode(globalSentryValues: GlobalSentryValu
   return `${injectedValuesCode}\n`;
 }
 
+type GlobalValuesInjectionOptions = {
+  getKitConfig: () => Promise<ResolvedKitConfig>;
+  getAdapterOutputDir: () => Promise<string>;
+  debug?: boolean;
+};
+
 /**
- * Injects SvelteKit app configuration values the svelte.config.js into the
- * server's global object so that the SDK can pick up the information at runtime
+ * Injects SvelteKit app configuration values into the server's global object
+ * so that the SDK can pick up the information at runtime.
  */
-export async function makeGlobalValuesInjectionPlugin(
-  svelteConfig: BackwardsForwardsCompatibleSvelteConfig,
-  options: Pick<SentrySvelteKitPluginOptions, 'adapter' | 'debug'>,
-): Promise<Plugin> {
-  const { adapter = 'other', debug = false } = options;
+export function makeGlobalValuesInjectionPlugin(options: GlobalValuesInjectionOptions): Plugin {
+  const { getKitConfig, getAdapterOutputDir, debug = false } = options;
 
-  const serverHooksFile = getHooksFileName(svelteConfig, 'server');
-  const adapterOutputDir = await getAdapterOutputDir(svelteConfig, adapter);
+  // The SvelteKit config is only available once Vite has resolved its plugins, so we compute
+  // the injected values lazily (but only once) instead of at plugin creation time.
+  let injectionValuesPromise: Promise<{ globalSentryValues: GlobalSentryValues; hooksFileRegexp: RegExp }> | undefined;
 
-  const globalSentryValues: GlobalSentryValues = {
-    __sentry_sveltekit_output_dir: adapterOutputDir,
-  };
+  const getInjectionValues = (): Promise<{ globalSentryValues: GlobalSentryValues; hooksFileRegexp: RegExp }> =>
+    (injectionValuesPromise ??= (async () => {
+      const kitConfig = await getKitConfig();
 
-  if (debug) {
-    // eslint-disable-next-line no-console
-    console.log('[Sentry SvelteKit] Global values:', globalSentryValues);
-  }
+      const serverHooksFile = getHooksFileName(kitConfig, 'server');
+      const adapterOutputDir = await getAdapterOutputDir();
+
+      const globalSentryValues: GlobalSentryValues = {
+        __sentry_sveltekit_output_dir: adapterOutputDir,
+      };
 
-  // oxlint-disable-next-line sdk/no-regexp-constructor -- not end user input + escaped anyway
-  const hooksFileRegexp = new RegExp(`/${escapeStringForRegex(serverHooksFile)}(.(js|ts|mjs|mts))?`);
+      if (debug) {
+        // eslint-disable-next-line no-console
+        console.log('[Sentry SvelteKit] Global values:', globalSentryValues);
+      }
+
+      return {
+        globalSentryValues,
+        // oxlint-disable-next-line sdk/no-regexp-constructor -- not end user input + escaped anyway
+        hooksFileRegexp: new RegExp(`/${escapeStringForRegex(serverHooksFile)}(.(js|ts|mjs|mts))?`),
+      };
+    })());
 
   return {
     name: 'sentry-sveltekit-global-values-injection-plugin',
+
+    // Eagerly, not on the first `transform`: see the note on the adapter output dir in
+    // `sentrySvelteKit()`. Awaited so a failure surfaces as a config error, not a stray rejection.
+    configResolved: async () => {
+      await getInjectionValues();
+    },
+
     resolveId: (id, _importer, _ref) => {
       if (id === VIRTUAL_GLOBAL_VALUES_FILE) {
         return {
@@ -70,8 +92,9 @@ export async function makeGlobalValuesInjectionPlugin(
       return null;
     },
 
-    load: id => {
+    load: async id => {
       if (id === VIRTUAL_GLOBAL_VALUES_FILE) {
+        const { globalSentryValues } = await getInjectionValues();
         return {
           code: getGlobalValueInjectionCode(globalSentryValues),
         };
@@ -80,6 +103,8 @@ export async function makeGlobalValuesInjectionPlugin(
     },
 
     transform: async (code, id) => {
+      const { hooksFileRegexp } = await getInjectionValues();
+
       const isServerEntryFile = /instrumentation\.server\./.test(id) || hooksFileRegexp.test(id);
 
       if (isServerEntryFile) {