feat: Add auto-reload on development environment

crates/app/src/main.rs

@@ -1,6 +1,8 @@
 use ::app::get_router;
+use listenfd::ListenFd;
 use std::env;
 use std::path::Path;
+use tokio::net::TcpListener;
 
 #[tokio::main]
 async fn main() {
@@ -8,10 +10,21 @@ async fn main() {
     let assets_path = Path::new(&manifest_dir).join("assets");
     let router = get_router(assets_path.as_path());
 
-    // TODO: select port based on available port (or ask in CLI)
-    let listener = tokio::net::TcpListener::bind("localhost:3000")
+    let mut listenfd = ListenFd::from_env();
+    let listener = match listenfd.take_tcp_listener(0).unwrap() {
+        // if we are given a tcp listener on listen fd 0, we use that one
+        Some(listener) => {
+            listener.set_nonblocking(true).unwrap();
+            TcpListener::from_std(listener).unwrap()
+        }
+        // otherwise fall back to local listening
+        None => TcpListener::bind("localhost:3000").await.unwrap(),
+    };
+
+    println!("Listening on: http://{}", listener.local_addr().unwrap());
+
+    // Run the server with the router
+    axum::serve(listener, router.into_make_service())
         .await
         .unwrap();
-    println!("Listening on: http://{}", listener.local_addr().unwrap());
-    axum::serve(listener, router).await.unwrap();
 }