Require specifying port on command line

src/main.rs

@@ -49,7 +49,16 @@ struct ApplicationState {
 
 #[tokio::main]
 async fn main() {
-    let image_path = args_os().nth(1).expect("Usage: image-gallery IMAGE_DIRECTORY");
+    let args = args_os()
+        .skip(1)
+        .collect::<Vec<_>>();
+    let args = args
+        .windows(2)
+        .next()
+        .expect("Usage: image-gallery IMAGE_DIRECTORY PORT");
+
+    let image_path = &args[0];
+    let port = args[1].to_string_lossy().parse::<u16>().expect("Invalid port specified");
 
     let mut secret_key: SecretKey = [0; 64];
     OsRng.fill_bytes(&mut secret_key);
@@ -107,7 +116,7 @@ async fn main() {
             cpu_task_limit: Arc::new(Semaphore::new(4)),
         });
 
-    let addr = SocketAddr::from(([0, 0, 0, 0], 9030));
+    let addr = SocketAddr::from(([0, 0, 0, 0], port));
     tracing::info!("listening on {}", addr);
     axum::Server::bind(&addr)
         .serve(app.into_make_service())