Tutorial 10: Static Assets & Pre-Compression 📦

The standard Server serves an existing static/ directory at /static. Production builds can create Brotli and Zstandard sidecars for eligible text and Wasm assets in that directory.

Step 1: Use the standard static directory

static/
├── css/
│   └── app.css
├── js/
│   └── app.js
└── favicon.svg

Reference those files through /static/..., for example /static/css/app.css. Server::run mounts the directory when it exists; no additional ServeDir layer is required for this standard path.

use rullst::{routes, routing::get, Server};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let app = routes![get("/" => || async { "Rullst" })];
    Server::new(app).run(3000).await?;
    Ok(())
}

If you mount a different directory manually through Axum/Tower, its routing and pre-compressed negotiation become application responsibilities.

Step 2: Build production sidecars

cargo rullst build

The release-mode command builds the application and creates .br and .zst siblings for html, css, js, json, svg, wasm, xml, and txt files under static/. The standard server negotiates Brotli through ServeDir and Zstandard through its static middleware.

Verify deployed behavior rather than assuming negotiation worked:

curl --compressed -I -H 'Accept-Encoding: br' \
  http://127.0.0.1:3000/static/css/app.css
curl -I -H 'Accept-Encoding: zstd' \
  http://127.0.0.1:3000/static/css/app.css

Check Content-Encoding, Content-Type, cache headers, and Vary through the actual TLS proxy/CDN. Pre-compression avoids compression work per request; it does not eliminate file I/O or network latency.

Key takeaways

• Use static/ for the framework’s standard asset path and build integration.
• Keep source files alongside generated sidecars in the deployed artifact.
• Fingerprint immutable asset names and configure cache policy at the application/CDN boundary.