fix(nuxt): proxy headers to islands + returned prerender hints (#21740)

packages/nuxt/src/app/components/nuxt-island.ts

@@ -4,6 +4,8 @@ import { hash } from 'ohash'
 import { appendResponseHeader } from 'h3'
 import { useHead } from '@unhead/vue'
 import { randomUUID } from 'uncrypto'
+import { withQuery } from 'ufo'
+
 // eslint-disable-next-line import/no-restricted-paths
 import type { NuxtIslandResponse } from '../../core/runtime/nitro/renderer'
 import { getFragmentHTML, getSlotProps } from './utils'
@@ -40,6 +42,7 @@ export default defineComponent({
     const hashId = computed(() => hash([props.name, props.props, props.context]))
     const instance = getCurrentInstance()!
     const event = useRequestEvent()
+    const eventFetch = process.server ? event.fetch : globalThis.fetch
     const mounted = ref(false)
     onMounted(() => { mounted.value = true })
 
@@ -78,13 +81,18 @@ export default defineComponent({
         appendResponseHeader(event, 'x-nitro-prerender', url)
       }
       // TODO: Validate response
-      const result = await $fetch<NuxtIslandResponse>(url, {
-        responseType: 'json',
-        params: {
-          ...props.context,
-          props: props.props ? JSON.stringify(props.props) : undefined
+      const r = await eventFetch(withQuery(url, {
+        ...props.context,
+        props: props.props ? JSON.stringify(props.props) : undefined
+      }))
+      const result = await r.json() as NuxtIslandResponse
+      // TODO: support passing on more headers
+      if (process.server && process.env.prerender) {
+        const hints = r.headers.get('x-nitro-prerender')
+        if (hints) {
+          appendResponseHeader(event, 'x-nitro-prerender', hints)
         }
-      })
+      }
       nuxtApp.payload.data[key] = {
         __nuxt_island: {
           key,

packages/nuxt/src/core/runtime/nitro/renderer.ts

@@ -367,7 +367,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
 
     await nitroApp.hooks.callHook('render:island', islandResponse, { event, islandContext })
 
-    const response: RenderResponse = {
+    const response = {
       body: JSON.stringify(islandResponse, null, 2),
       statusCode: event.node.res.statusCode,
       statusMessage: event.node.res.statusMessage,
@@ -375,7 +375,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
         'content-type': 'application/json;charset=utf-8',
         'x-powered-by': 'Nuxt'
       }
-    }
+    } satisfies RenderResponse
     if (process.env.prerender) {
       ISLAND_CACHE!.set(`/__nuxt_island/${islandContext!.name}_${islandContext!.id}`, response)
     }
@@ -383,7 +383,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
   }
 
   // Construct HTML response
-  const response: RenderResponse = {
+  const response = {
     body: renderHTMLDocument(htmlContext),
     statusCode: event.node.res.statusCode,
     statusMessage: event.node.res.statusMessage,
@@ -391,7 +391,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
       'content-type': 'text/html;charset=utf-8',
       'x-powered-by': 'Nuxt'
     }
-  }
+  } satisfies RenderResponse
 
   return response
 })
@@ -456,7 +456,7 @@ async function renderInlineStyles (usedModules: Set<string> | string[]) {
 }
 
 function renderPayloadResponse (ssrContext: NuxtSSRContext) {
-  return <RenderResponse> {
+  return {
     body: process.env.NUXT_JSON_PAYLOADS
       ? stringify(splitPayload(ssrContext).payload, ssrContext._payloadReducers)
       : `export default ${devalue(splitPayload(ssrContext).payload)}`,
@@ -466,7 +466,7 @@ function renderPayloadResponse (ssrContext: NuxtSSRContext) {
       'content-type': process.env.NUXT_JSON_PAYLOADS ? 'application/json;charset=utf-8' : 'text/javascript;charset=utf-8',
       'x-powered-by': 'Nuxt'
     }
-  }
+  } satisfies RenderResponse
 }
 
 function renderPayloadJsonScript (opts: { id: string, ssrContext: NuxtSSRContext, data?: any, src?: string }) {

test/basic.test.ts

@@ -1,9 +1,10 @@
+import { readdir } from 'node:fs/promises'
 import { fileURLToPath } from 'node:url'
 import { describe, expect, it } from 'vitest'
 import { joinURL, withQuery } from 'ufo'
 import { isCI, isWindows } from 'std-env'
-import { normalize } from 'pathe'
-import { $fetch, createPage, fetch, isDev, setup, startServer, url } from '@nuxt/test-utils'
+import { join, normalize } from 'pathe'
+import { $fetch, createPage, fetch, isDev, setup, startServer, url, useTestContext } from '@nuxt/test-utils'
 import { $fetchComponent } from '@nuxt/test-utils/experimental'
 
 import type { NuxtIslandResponse } from '../packages/nuxt/src/core/runtime/nitro/renderer'
@@ -418,39 +419,6 @@ describe('pages', () => {
     await page.close()
   })
 
-  it('/islands', async () => {
-    const page = await createPage('/islands')
-    await page.waitForLoadState('networkidle')
-    await page.locator('#increase-pure-component').click()
-    await page.waitForResponse(response => response.url().includes('/__nuxt_island/') && response.status() === 200)
-    await page.waitForLoadState('networkidle')
-    expect(await page.locator('#slot-in-server').first().innerHTML()).toContain('Slot with in .server component')
-    expect(await page.locator('#test-slot').first().innerHTML()).toContain('Slot with name test')
-
-    // test fallback slot with v-for
-    expect(await page.locator('.fallback-slot-content').all()).toHaveLength(2)
-    // test islands update
-    expect(await page.locator('.box').innerHTML()).toContain('"number": 101,')
-    await page.locator('#update-server-components').click()
-    await Promise.all([
-      page.waitForResponse(response => response.url().includes('/__nuxt_island/LongAsyncComponent') && response.status() === 200),
-      page.waitForResponse(response => response.url().includes('/__nuxt_island/AsyncServerComponent') && response.status() === 200)
-    ])
-    await page.waitForLoadState('networkidle')
-    expect(await page.locator('#async-server-component-count').innerHTML()).toContain(('1'))
-    expect(await page.locator('#long-async-component-count').innerHTML()).toContain('1')
-
-    // test islands slots interactivity
-    await page.locator('#first-sugar-counter button').click()
-    expect(await page.locator('#first-sugar-counter').innerHTML()).toContain('Sugar Counter 13')
-
-    // test islands mounted client side with slot
-    await page.locator('#show-island').click()
-    expect(await page.locator('#island-mounted-client-side').innerHTML()).toContain('Interactive testing slot post SSR')
-
-    await page.close()
-  })
-
   it('/legacy-async-data-fail', async () => {
     const response = await fetch('/legacy-async-data-fail').then(r => r.text())
     expect(response).not.toContain('don\'t look at this')
@@ -1246,6 +1214,51 @@ describe.skipIf(isDev() || isWebpack)('inlining component styles', () => {
   })
 })
 
+describe('server components/islands', () => {
+  it('/islands', async () => {
+    const page = await createPage('/islands')
+    await page.waitForLoadState('networkidle')
+    await page.locator('#increase-pure-component').click()
+    await page.waitForResponse(response => response.url().includes('/__nuxt_island/') && response.status() === 200)
+    await page.waitForLoadState('networkidle')
+    expect(await page.locator('#slot-in-server').first().innerHTML()).toContain('Slot with in .server component')
+    expect(await page.locator('#test-slot').first().innerHTML()).toContain('Slot with name test')
+
+    // test fallback slot with v-for
+    expect(await page.locator('.fallback-slot-content').all()).toHaveLength(2)
+    // test islands update
+    expect(await page.locator('.box').innerHTML()).toContain('"number": 101,')
+    await page.locator('#update-server-components').click()
+    await Promise.all([
+      page.waitForResponse(response => response.url().includes('/__nuxt_island/LongAsyncComponent') && response.status() === 200),
+      page.waitForResponse(response => response.url().includes('/__nuxt_island/AsyncServerComponent') && response.status() === 200)
+    ])
+    await page.waitForLoadState('networkidle')
+    expect(await page.locator('#async-server-component-count').innerHTML()).toContain(('1'))
+    expect(await page.locator('#long-async-component-count').innerHTML()).toContain('1')
+
+    // test islands slots interactivity
+    await page.locator('#first-sugar-counter button').click()
+    expect(await page.locator('#first-sugar-counter').innerHTML()).toContain('Sugar Counter 13')
+
+    // test islands mounted client side with slot
+    await page.locator('#show-island').click()
+    expect(await page.locator('#island-mounted-client-side').innerHTML()).toContain('Interactive testing slot post SSR')
+
+    await page.close()
+  })
+
+  it.skipIf(isDev)('should allow server-only components to set prerender hints', async () => {
+    // @ts-expect-error ssssh! untyped secret property
+    const publicDir = useTestContext().nuxt._nitro.options.output.publicDir
+    expect(await readdir(join(publicDir, 'some', 'url', 'from', 'server-only', 'component')).catch(() => [])).toContain(
+      isRenderingJson
+        ? '_payload.json'
+        : '_payload.js'
+    )
+  })
+})
+
 describe.skipIf(isDev() || isWindows || !isRenderingJson)('prefetching', () => {
   it('should prefetch components', async () => {
     await expectNoClientErrors('/prefetch/components')

test/fixtures/basic/components/ServerOnlyComponent.server.vue

@@ -4,6 +4,12 @@
   </div>
 </template>
 
+<script setup>
+import { appendResponseHeader } from 'h3'
+
+appendResponseHeader(useRequestEvent(), 'x-nitro-prerender', '/some/url/from/server-only/component')
+</script>
+
 <style>
 :root {
   --server-only: 'server-only';