[NEXT-1071] Static sitemap route is not optimized as static

[arialpew]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
      Platform: win32
      Arch: x64
      Version: Windows 10 Pro
Binaries:
      Node: 20.0.0
      npm: N/A
      Yarn: N/A
      pnpm: N/A
Relevant packages:
      next: 13.3.2
      eslint-config-next: 13.3.1
      react: 18.2.0
      react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

App directory (appDir: true), Metadata (metadata, generateMetadata, next/head, head.js)

Link to the code that reproduces this issue

Install a standard Next.js setup v13.3.2 and use static export + new appDir and add an app/sitemap.ts file.

next.config.js file :

/** @type {import('next').NextConfig} */
const nextConfig = {
  output: 'export',
  pageExtensions: ['ts', 'tsx', 'js', 'jsx'],
  reactStrictMode: true,
  swcMinify: true,
  // Note: This feature is required to use NextJS Image in SSG mode.
  // See https://nextjs.org/docs/messages/export-image-api for different workarounds.
  images: {
    unoptimized: true,
  },
  experimental: {
    appDir: true,
  },
}

To Reproduce

• Static export output mode.
• Using the new appDir experimental.
• Version 13.3.2 (currently latest version).
• Windows 10 (no WSL).

When running npm run build, sitemap isn't generated. In development mode, the sitemap is accessible.

app/sitemap.ts file :

import { MetadataRoute } from 'next'
import { allBlogs } from '@/.contentlayer/generated'

export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
  const blogs = allBlogs.map(post => ({
    url: `http://localhost:3000/blog/${post.slug}`,
    lastModified: post.publishedAt,
  }))

  const routes = ['', '/blog', '/contact'].map(route => ({
    url: `http://localhost:3000${route}`,
    lastModified: new Date().toISOString().split('T')[0],
  }))

  return [...routes, ...blogs]
}

Build log :

Route (app)                                Size     First Load JS
┌ ○ /                                      175 B          81.7 kB
├ ● /blog/[slug]                           2.5 kB           84 kB
├   ├ /blog/post-0002
├   └ /blog/post-0001
├ ○ /robots.txt                            0 B                0 B
└ λ /sitemap.xml/[[...__metadata_id__]]    0 B                0 B
+ First Load JS shared by all              75.9 kB
  ├ chunks/139-95fe43fc14e42daa.js         23.6 kB
  ├ chunks/2443530c-dfeca1b6f38a1e91.js    50.5 kB
  ├ chunks/main-app-06da1dca58d74c34.js    214 B
  └ chunks/webpack-d9bdffe382ff608b.js     1.69 kB

Route (pages)                              Size     First Load JS
─ ○ /404                                   178 B            86 kB
+ First Load JS shared by all              85.8 kB
  ├ chunks/main-470121997414b370.js        83.9 kB
  ├ chunks/pages/_app-c544d6df833bfd4a.js  192 B
  └ chunks/webpack-d9bdffe382ff608b.js     1.69 kB

λ  (Server)  server-side renders at runtime (uses getInitialProps or getServerSideProps)
○  (Static)  automatically rendered as static HTML (uses no initial props)
●  (SSG)     automatically generated as static HTML + JSON (uses getStaticProps)

As you can see, sitemap end up with a weird filename /sitemap.xml/[[...__metadata_id__]] and it didn't write to the file system. Robots is fine, but sitemap doesn't end up in the out folder in production build.

Describe the Bug

A sitemap isn't generated in the out folder when runnning npm run build.

Expected Behavior

A sitemap should be generated in the out folder when runnning npm run build.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

_{From SyncLinear.com | NEXT-1071}

[arialpew]

Since the sitemap work in development but isn't generated in production build (where we opted for static export), I suspect it's not because of filename or filesystem write, but more about the fact that Next.js consider the sitemap as "server-side renders at runtime" - but it should not, this conflict with the static export in next.config.js, hence the issue.

[github-actions]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.