warn once for metadataBase missing

packages/next/src/build/output/log.ts

@@ -37,3 +37,11 @@ export function event(...message: any[]) {
 export function trace(...message: any[]) {
   console.log(prefixes.trace, ...message)
 }
+
+const uniqueWarnings = new Set()
+export function warnOnce(...message: any[]) {
+  const key = message.join(' ')
+  if (uniqueWarnings.has(key)) return
+  uniqueWarnings.add(key)
+  warn(...message)
+}

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

@@ -26,9 +26,9 @@ function resolveUrl(
 
   if (!metadataBase) {
     metadataBase = new URL(`http://localhost:${process.env.PORT || 3000}`)
-    // Development mode warning, add new line prefix for worker output
+    // next build mode warning, add new line prefix for worker output
     console.log()
-    Log.warn(
+    Log.warnOnce(
       `metadata.metadataBase is not set for resolving url "${url}", fallbacks to "${metadataBase.origin}". See https://beta.nextjs.org/docs/api-reference/metadata#metadatabase`
     )
   }

test/e2e/app-dir/metadata-missing-metadata-base/index.test.ts

@@ -1,31 +1,21 @@
-import { createNext, FileRef } from 'e2e-utils'
-import { NextInstance } from 'test/lib/next-modes/base'
-import { fetchViaHTTP } from 'next-test-utils'
+import { createNextDescribe } from 'e2e-utils'
 
-describe('app dir - metadata missing metadataBase', () => {
-  let next: NextInstance
-
-  if ((global as any).isNextDeploy) {
-    return it('should skip for deploy', () => {})
-  }
-
-  beforeAll(async () => {
-    next = await createNext({
-      skipStart: true,
-      files: new FileRef(__dirname),
+createNextDescribe(
+  'app dir - metadata missing metadataBase',
+  {
+    files: __dirname,
+    skipDeployment: true,
+  },
+  ({ next }) => {
+    it('should fallback to localhost if metadataBase is missing for absolute urls resolving', async () => {
+      await next.fetch('/blog')
+      expect(next.cliOutput).toInclude(
+        'metadata.metadataBase is not set for resolving url "/blog/opengraph-image?'
+      )
+      expect(next.cliOutput).toInclude(', fallbacks to "http://localhost:')
+      expect(next.cliOutput).toInclude(
+        '. See https://beta.nextjs.org/docs/api-reference/metadata#metadatabase'
+      )
     })
-  })
-  afterAll(() => next.destroy())
-
-  it('should fallback to localhost if metadataBase is missing for absolute urls resolving', async () => {
-    await next.start()
-    await fetchViaHTTP(next.url, '/blog')
-    expect(next.cliOutput).toInclude(
-      'metadata.metadataBase is not set for resolving url "/blog/opengraph-image?'
-    )
-    expect(next.cliOutput).toInclude(', fallbacks to "http://localhost:')
-    expect(next.cliOutput).toInclude(
-      '. See https://beta.nextjs.org/docs/api-reference/metadata#metadatabase'
-    )
-  })
-})
+  }
+)