Sitemap image tag support (#68034)

Image Tag should be available in sitemap.xml, which is not currently
support in sitemap.

In this pr, I solved issue #68033  which I faced in my project.

cc  @leerob @delbaoliveira  @samcx 

x-ref:
https://developers.google.com/search/docs/crawling-indexing/sitemaps/image-sitemaps

---------

Co-authored-by: Jiachi Liu <inbox@huozhi.im>
Co-authored-by: Delba de Oliveira <32464864+delbaoliveira@users.noreply.github.com>

Author: 3 people

docs/02-app/02-api-reference/02-file-conventions/01-metadata/sitemap.mdx

@@ -120,6 +120,46 @@ Output:
 </urlset>
 ```
 
+### Image Sitemaps
+
+You can use `images` property to create image sitemaps. Learn more details in the [Google Developer Docs](https://developers.google.com/search/docs/crawling-indexing/sitemaps/image-sitemaps).
+
+```ts filename="app/sitemap.ts" switcher
+import type { MetadataRoute } from 'next'
+
+export default function sitemap(): MetadataRoute.Sitemap {
+  return [
+    {
+      url: 'https://example.com',
+      lastModified: '2021-01-01',
+      changeFrequency: 'weekly',
+      priority: 0.5,
+      images: ['https://example.com/image.jpg'],
+    },
+  ]
+}
+```
+
+Output:
+
+```xml filename="acme.com/sitemap.xml"
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset
+  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+  xmlns:image="http://www.google.com/schemas/sitemap-image/1.1"
+>
+  <url>
+    <loc>https://example.com</loc>
+    <image:image>
+      <image:loc>https://example.com/image.jpg</image:loc>
+    </image:image>
+    <lastmod>2021-01-01</lastmod>
+    <changefreq>weekly</changefreq>
+    <priority>0.5</priority>
+  </url>
+</urlset>
+```
+
 ### Generate a localized Sitemap
 
 ```ts filename="app/sitemap.ts" switcher

packages/next/src/build/webpack/loaders/metadata/resolve-route-data.test.ts

@@ -126,5 +126,32 @@ describe('resolveRouteData', () => {
         "
       `)
     })
+    it('should resolve sitemap.xml with images', () => {
+      expect(
+        resolveSitemap([
+          {
+            url: 'https://example.com',
+            lastModified: '2021-01-01',
+            changeFrequency: 'weekly',
+            priority: 0.5,
+            images: ['https://example.com/image.jpg'],
+          },
+        ])
+      ).toMatchInlineSnapshot(`
+        "<?xml version="1.0" encoding="UTF-8"?>
+        <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">
+        <url>
+        <loc>https://example.com</loc>
+        <image:image>
+        <image:loc>https://example.com/image.jpg</image:loc>
+        </image:image>
+        <lastmod>2021-01-01</lastmod>
+        <changefreq>weekly</changefreq>
+        <priority>0.5</priority>
+        </url>
+        </urlset>
+        "
+      `)
+    })
   })
 })

packages/next/src/build/webpack/loaders/metadata/resolve-route-data.ts

@@ -47,10 +47,14 @@ export function resolveSitemap(data: MetadataRoute.Sitemap): string {
   const hasAlternates = data.some(
     (item) => Object.keys(item.alternates ?? {}).length > 0
   )
+  const hasImages = data.some((item) => Boolean(item.images?.length))
 
   let content = ''
   content += '<?xml version="1.0" encoding="UTF-8"?>\n'
   content += '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"'
+  if (hasImages) {
+    content += ' xmlns:image="http://www.google.com/schemas/sitemap-image/1.1"'
+  }
   if (hasAlternates) {
     content += ' xmlns:xhtml="http://www.w3.org/1999/xhtml">\n'
   } else {
@@ -70,6 +74,11 @@ export function resolveSitemap(data: MetadataRoute.Sitemap): string {
         }" />\n`
       }
     }
+    if (item.images?.length) {
+      for (const image of item.images) {
+        content += `<image:image>\n<image:loc>${image}</image:loc>\n</image:image>\n`
+      }
+    }
     if (item.lastModified) {
       const serializedDate =
         item.lastModified instanceof Date

packages/next/src/lib/metadata/types/metadata-interface.ts

@@ -607,6 +607,7 @@ type SitemapFile = Array<{
   alternates?: {
     languages?: Languages<string>
   }
+  images?: string[]
 }>
 
 type ResolvingMetadata = Promise<ResolvedMetadata>

test/e2e/app-dir/metadata-dynamic-routes/app/sitemap-image/sitemap.ts

@@ -0,0 +1,20 @@
+import { MetadataRoute } from 'next'
+
+export default function sitemap(): MetadataRoute.Sitemap {
+  return [
+    {
+      url: 'https://example.com',
+      lastModified: '2024-01-01',
+      changeFrequency: 'daily',
+      priority: 0.5,
+    },
+    {
+      url: 'https://example.com/about',
+      lastModified: '2024-01-01',
+      images: [
+        'https://example.com/image1.jpg',
+        'https://example.com/image2.jpg',
+      ],
+    },
+  ]
+}

test/e2e/app-dir/metadata-dynamic-routes/index.test.ts

@@ -103,6 +103,18 @@ describe('app dir - metadata dynamic routes', () => {
         `<xhtml:link rel="alternate" hreflang="de" href="https://example.com/de/about" />`
       )
     })
+
+    it('should support images in sitemap', async () => {
+      const xml = await (await next.fetch('/sitemap-image/sitemap.xml')).text()
+
+      expect(xml).toContain(
+        `<image:image>\n<image:loc>https://example.com/image1.jpg</image:loc>\n</image:image>`
+      )
+      expect(xml).toContain(
+        `<image:image>\n<image:loc>https://example.com/image2.jpg</image:loc>\n</image:image>`
+      )
+    })
+
     if (isNextStart) {
       it('should optimize routes without multiple generation API as static routes', async () => {
         const appPathsManifest = JSON.parse(

test/turbopack-build-tests-manifest.json

@@ -2063,6 +2063,7 @@
         "app dir - metadata dynamic routes sitemap should not throw if client components are imported but not used in sitemap",
         "app dir - metadata dynamic routes sitemap should optimize routes without multiple generation API as static routes",
         "app dir - metadata dynamic routes sitemap should support alternate.languages in sitemap",
+        "app dir - metadata dynamic routes sitemap should support images in sitemap",
         "app dir - metadata dynamic routes sitemap should support generate multi sitemaps with generateSitemaps",
         "app dir - metadata dynamic routes social image routes should fill params into dynamic routes url of metadata images",
         "app dir - metadata dynamic routes social image routes should fill params into routes groups url of static images",