Astrum

axum + Astro, shipped as one binary.

Astro builds static pages. axum serves them: from disk while you develop, from inside the executable in release. There is no astro dev and no second port.

Requirements

rust, bun, and watchexec (for dev.sh).

Develop

./dev.sh

Opens on http://127.0.0.1:8080. It installs frontend dependencies on first run, then watches two things at once:

• Rust changes restart the server (watchexec).
• Anything under frontend/ makes the server run bun run build and push reload to every browser on /dev-ws.

Build for production

./build.sh      # -> backend/target/release/astrum

That rebuilds the frontend without PUBLIC_HOT_RELOAD, then compiles with --no-default-features so the watcher, bun and /dev-ws are left out entirely. The result is one self-contained file; copy it anywhere and run it.

How hot reload is wired

Where	What
backend/src/dev.rs	Runs bun run build with PUBLIC_HOT_RELOAD=true, watches frontend/, broadcasts to /dev-ws.
frontend/src/components/DevReload.astro	Emits the client script only when PUBLIC_HOT_RELOAD === "true", so a production page has none of it.
hot-reload cargo feature	Compiles all of the above in. On by default; --no-default-features drops it and the notify dependency.

The env var is what connects the two halves: the Rust side sets it when it invokes bun, and the Astro build decides from it whether the page opens a socket at all.

Environment

Variable	Default	Meaning
HOST	127.0.0.1	Bind address.
PORT	8080	Bind port.
FRONTEND_WATCH	on in debug, off in release	Rebuild the frontend and serve reloads.
DEBOUNCE_MILLIS	500	Quiet period after an edit before rebuilding.
RUST_LOG	info	Log filter.

Layout

backend/
  build.rs            cargo can't see frontend/dist; this makes it rebuild when it changes
  src/main.rs         routes, config, startup
  src/frontend.rs     serves dist: disk in debug, embedded in release
  src/dev.rs          bun rebuild, file watcher, /dev-ws
frontend/
  src/pages/          one file per route (index, about, 404)
  src/layouts/        page shell
  src/components/     DevReload
  src/styles/         Tailwind entry and theme tokens

Notes

• frontend/dist has to exist before the server compiles, since rust-embed reads it at compile time. dev.sh and build.sh both handle that.
• Astro emits about/index.html; the server resolves /about and /about/ to it, and unknown paths get 404.astro.
• Add a route in axum by adding to the router in main.rs. Add a page by dropping a .astro file in frontend/src/pages/.