Option to Save Static HTML in static/ Directory

[rlagudals95]

Goals

1. Allow users to save SSG-generated HTML files in the static/ directory, making it easier for traditional server-based deployments to manage static assets.
2. Provide an intuitive directory structure for managing truly static files (e.g., CSS, images, HTML) in environments where serverless is not used.
3. Reduce the need for manual post-build file relocation or custom scripts for static file management.

Non-Goals

1. This feature does not aim to change how dynamic or SSR pages are handled in Next.js.
2. This feature does not aim to replace the existing .next/server/pages structure for serverless environments.
3. This feature does not interfere with Incremental Static Regeneration (ISR) behavior or its cache mechanisms.

Background

In traditional server environments, where serverless features like ISR or API routes are not utilized, storing SSG-generated HTML files in the .next/server/pages directory is less intuitive. Users often expect these files to be located in a directory like static/, alongside other static assets such as images and CSS.

Why this feature is needed:

1. In traditional server deployments, it is often necessary to manually move static HTML files after build to better manage them and to use cdn with other static files.
2. Users expect a clear separation of static assets and server-specific files.
3. Aligning HTML with static resources can simplify deployment pipelines in non-serverless environments.

Current alternatives:

1. Use next export to generate static HTML files in an out/ directory. However, this approach is limited to fully static sites and does not support partial SSG combined with SSR.
2. Manually relocate files post-build, which adds complexity to the deployment process.

Proposal

Implementation Plan:

1. Introduce a new experimental configuration option in next.config.js

module.exports = {
  experimental: {
    outputStaticHtml: true,
  },
};

2. If the option is enabled, modify the SSG build process to save static HTML files in the static/ directory instead of .next/server/pages.
   HTML files for SSG pages (getStaticProps) will be stored in .next/static/.
   Associated JSON data will remain in .next/server/pages to maintain compatibility with dynamic rendering features like ISR.

3. Provide clear documentation to explain when and why to use this feature.