fix(ssr): no external symlink package

packages/vite/src/node/plugins/resolve.ts

@@ -87,7 +87,7 @@ export interface InternalResolveOptions extends ResolveOptions {
   ssrOptimizeCheck?: boolean
   // Resolve using esbuild deps optimization
   getDepsOptimizer?: (ssr: boolean) => DepsOptimizer | undefined
-  shouldExternalize?: (id: string) => boolean | undefined
+  shouldExternalize?: (id: string) => boolean
 }
 
 export function resolvePlugin(resolveOptions: InternalResolveOptions): Plugin {

packages/vite/src/node/ssr/ssrExternal.ts

@@ -90,13 +90,13 @@ const _require = createRequire(import.meta.url)
 
 const isSsrExternalCache = new WeakMap<
   ResolvedConfig,
-  (id: string) => boolean | undefined
+  (id: string) => boolean
 >()
 
 export function shouldExternalizeForSSR(
   id: string,
   config: ResolvedConfig
-): boolean | undefined {
+): boolean {
   let isSsrExternal = isSsrExternalCache.get(config)
   if (!isSsrExternal) {
     isSsrExternal = createIsSsrExternal(config)
@@ -151,46 +151,56 @@ export function createIsConfiguredAsSsrExternal(
   }
 }
 
-function createIsSsrExternal(
-  config: ResolvedConfig
-): (id: string) => boolean | undefined {
-  const processedIds = new Map<string, boolean | undefined>()
-
-  const { ssr, root } = config
+function createIsSsrExternal(config: ResolvedConfig): (id: string) => boolean {
+  const processedIds = new Map<string, boolean>()
 
   const isConfiguredAsExternal = createIsConfiguredAsSsrExternal(config)
 
   const resolveOptions: InternalResolveOptions = {
-    root,
+    root: config.root,
     preserveSymlinks: config.resolve.preserveSymlinks,
     isProduction: false,
     isBuild: true
   }
 
-  const isExternalizable = (id: string) => {
-    if (!bareImportRE.test(id) || id.includes('\0')) {
-      return false
-    }
-    return !!tryNodeResolve(
+  const resolve = (id: string) => {
+    return tryNodeResolve(
       id,
       undefined,
       resolveOptions,
-      ssr?.target === 'webworker',
+      config.ssr?.target === 'webworker',
       undefined,
       true,
-      true // try to externalize, will return undefined if not possible
+      false
     )
   }
 
+  const isExternal = (id: string) => {
+    if (id.startsWith('.') || path.isAbsolute(id) || isBuiltin(id)) {
+      return false
+    }
+    // check config for external/noExternal, undefined if not explicitly configured
+    const isConfigExternal = isConfiguredAsExternal(id)
+    if (isConfigExternal !== undefined) {
+      return isConfigExternal
+    }
+    // no external non-dep import or virtual files
+    if (!bareImportRE.test(id) || id.includes('\0')) {
+      return false
+    }
+    // no external if can't resolve or is symlink package
+    const resolved = resolve(id)
+    if (!resolved || !resolved.id.includes('node_modules')) {
+      return false
+    }
+    return true
+  }
+
   return (id: string) => {
     if (processedIds.has(id)) {
-      return processedIds.get(id)
-    }
-    let external = false
-    if (!id.startsWith('.') && !path.isAbsolute(id)) {
-      external =
-        isBuiltin(id) || (isConfiguredAsExternal(id) ?? isExternalizable(id))
+      return processedIds.get(id)!
     }
+    const external = isExternal(id)
     processedIds.set(id, external)
     return external
   }

playground/ssr-deps/__tests__/ssr-deps.spec.ts

@@ -98,3 +98,8 @@ test('msg from external using external entry', async () => {
     'Hello World!'
   )
 })
+
+test('msg from linked no external', async () => {
+  await page.goto(url)
+  expect(await page.textContent('.linked-no-external')).toMatch('Hello World!')
+})

playground/ssr-deps/linked-no-external/index.js

@@ -0,0 +1,5 @@
+export const hello = function () {
+  // make sure linked package is not externalized so Vite features like
+  // import.meta.env works (or handling TS files)
+  return import.meta.env.DEV && 'Hello World!'
+}

playground/ssr-deps/linked-no-external/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "linked-no-external",
+  "private": true,
+  "type": "module",
+  "version": "0.0.0"
+}

playground/ssr-deps/package.json

@@ -26,7 +26,8 @@
     "optimized-with-nested-external": "file:./optimized-with-nested-external",
     "optimized-cjs-with-nested-external": "file:./optimized-with-nested-external",
     "external-using-external-entry": "file:./external-using-external-entry",
-    "external-entry": "file:./external-entry"
+    "external-entry": "file:./external-entry",
+    "linked-no-external": "link:./linked-no-external"
   },
   "devDependencies": {
     "cross-env": "^7.0.3",

playground/ssr-deps/src/app.js

@@ -11,6 +11,7 @@ import onlyObjectAssignedExports from 'only-object-assigned-exports'
 import requireAbsolute from 'require-absolute'
 import noExternalCjs from 'no-external-cjs'
 import importBuiltinCjs from 'import-builtin-cjs'
+import { hello as linkedNoExternal } from 'linked-no-external'
 
 // This import will set a 'Hello World!" message in the nested-external non-entry dependency
 import 'non-optimized-with-nested-external'
@@ -75,5 +76,8 @@ export async function render(url, rootDir) {
   const externalUsingExternalEntryMessage = externalUsingExternalEntry.hello()
   html += `\n<p class="external-using-external-entry">message from external-using-external-entry: ${externalUsingExternalEntryMessage}</p>`
 
+  const linkedNoExternalMessage = linkedNoExternal()
+  html += `\n<p class="linked-no-external">message from linked-no-external: ${linkedNoExternalMessage}</p>`
+
   return html + '\n'
 }