feat(server): graceful shutdown on SIGINT/SIGTERM (#1)

crates/server/src/lib.rs

@@ -64,6 +64,34 @@ pub async fn run(config: Config) -> anyhow::Result<()> {
     serve(listener, state).await
 }
 
+/// Resolves when the process receives SIGINT (Ctrl-C) or SIGTERM, so the server can
+/// drain in-flight requests before exiting.
+async fn shutdown_signal() {
+    let ctrl_c = async {
+        tokio::signal::ctrl_c()
+            .await
+            .expect("install Ctrl-C handler");
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate())
+            .expect("install SIGTERM handler")
+            .recv()
+            .await;
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {},
+        _ = terminate => {},
+    }
+
+    tracing::info!("shutdown signal received; draining");
+}
+
 /// Serve the API on an already-bound listener (used by `run` and tests).
 pub async fn serve(listener: TcpListener, state: AppState) -> anyhow::Result<()> {
     let app = build_app(state);
@@ -72,6 +100,7 @@ pub async fn serve(listener: TcpListener, state: AppState) -> anyhow::Result<()>
     let app = app.merge(web_assets::routes());
 
     axum::serve(listener, app)
+        .with_graceful_shutdown(shutdown_signal())
         .await
         .context("running the HTTP server")?;