add Dockerfile

backend/src/main.rs

@@ -210,10 +210,14 @@ async fn frontend(path: PathBuf) -> Option<NamedFile> {
     let frontend_base = env::var("FRONTEND_BASE").unwrap_or("../frontend/dist/".into());
     let frontend_path = Path::new(&frontend_base).join(path);
     let frontend_index_path = Path::new(&frontend_base).join("index.html");
-    NamedFile::open(frontend_path)
-        .await
-        .or(NamedFile::open(frontend_index_path).await)
-        .ok()
+
+    match tokio::fs::metadata(&frontend_path).await {
+        Ok(meta) if meta.is_file() => NamedFile::open(frontend_path)
+            .await
+            .or(NamedFile::open(frontend_index_path).await)
+            .ok(),
+        _ => NamedFile::open(&frontend_index_path).await.ok(),
+    }
 }
 
 #[launch]