Shared multi-tenant Keystatic server

[Daniel15]

I've been evaluating a bunch of headless CMSes for use with static Astro sites (no server-side code, and minimal JS), and Keystatic is one of the top ones. It hits a good balance in terms of functionality vs ease of installation and maintenance. It's good to see some quality Aussie-made software 🇦🇺

The one issue is that it requires a backend to be added to the site. It's not uncommon for static sites to be hosted somewhere that doesn't allow server-side code, for example on a CDN (CloudFront + S3, BunnyCDN + Bunny Storage, etc) or even just on GitHub Pages. A workaround is to have a dual deployment, where the site is deployed to both a static host (for the production site), and somewhere else that can run server-side code (only for editing).

In my case, I self-host my sites and try to avoid anything remotely-hosted such as Netlify or Vercel, so in order to use Keystatic I'd have to run a Node.js process per site. This is fine, but I'd like to see a version of Keystatic where the frontend and backend are less tightly coupled.

What I'd love to see is an option where I could run a single shared Node.js Keystatic server, that multiple Keystatic-powered sites could use. It could take the repository owner and name as a path or querystring parameter (e.g. cms.example.com/api/keystatic/github/Daniel15/Example/...) rather than from an environment variable. Instead of assuming the site files are on disk, it would clone the repo into a temp directory and use that. The Keystatic-powered site would still have a local copy of Keystatic, but it'd communicate to the remote API.