Fallback to deployment vercel url if metadataBase is not set on prod (#…

…48570)

x-ref:
#48556 (comment)

For production deployment, we still fallback to deployment URL if
`metadataBase` is not set.

packages/next/src/lib/metadata/resolvers/resolve-url.ts

@@ -14,13 +14,16 @@ export function getFallbackMetadataBaseIfPresent(
   metadataBase: URL | null
 ): URL | null {
   const defaultMetadataBase = createLocalMetadataBase()
+  const deploymentUrl =
+    process.env.VERCEL_URL && new URL(`https://${process.env.VERCEL_URL}`)
+  if (process.env.NODE_ENV === 'development') {
+    return defaultMetadataBase
+  }
   return process.env.NODE_ENV === 'production' &&
-    process.env.VERCEL_URL &&
+    deploymentUrl &&
     process.env.VERCEL_ENV === 'preview'
-    ? new URL(`https://${process.env.VERCEL_URL}`)
-    : process.env.NODE_ENV === 'development'
-    ? defaultMetadataBase
-    : metadataBase || defaultMetadataBase
+    ? deploymentUrl
+    : metadataBase || deploymentUrl || defaultMetadataBase
 }
 
 function resolveUrl(url: null | undefined, metadataBase: URL | null): null

test/e2e/app-dir/metadata-dynamic-routes/app/metadata-base/unset/page.tsx

@@ -0,0 +1,11 @@
+export default function page() {
+  return (
+    <div>
+      <h1>Unset</h1>
+    </div>
+  )
+}
+
+export const metadata = {
+  metadataBase: null,
+}

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

@@ -305,6 +305,21 @@ createNextDescribe(
       )
     })
 
+    it('should use localhost for local prod and fallback to deployment url when metadataBase is falsy', async () => {
+      const $ = await next.render$('/metadata-base/unset')
+      const twitterImage = $('meta[name="twitter:image"]').attr('content')
+
+      if (isNextDeploy) {
+        expect(twitterImage).toMatch(
+          /https:\/\/\w+.vercel.app\/metadata-base\/unset\/twitter-image\.png/
+        )
+      } else {
+        expect(twitterImage).toMatch(
+          /http:\/\/localhost:\d+\/metadata-base\/unset\/twitter-image\.png/
+        )
+      }
+    })
+
     if (isNextStart) {
       it('should support edge runtime of image routes', async () => {
         const middlewareManifest = JSON.parse(