Fix blank screen: Implement robust Nginx Proxy with WebSocket support

Dockerfile

@@ -5,8 +5,12 @@ WORKDIR /app
 # Install system dependencies
 RUN apt-get update && apt-get install -y \
     bash \
+    nginx \
     && rm -rf /var/lib/apt/lists/*
 
+# Copy Nginx configuration
+COPY nginx.conf /etc/nginx/nginx.conf
+
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
@@ -18,4 +22,5 @@ RUN chmod +x start.sh
 ENV PYTHONPATH=/app
 EXPOSE 7860
 
+# We use start.sh to launch FastAPI, Streamlit, and Nginx
 CMD ["./start.sh"]

gateway.py

@@ -1,59 +0,0 @@
-import os
-import httpx
-from fastapi import FastAPI, Request, Response
-from fastapi.responses import StreamingResponse
-from server.app import app as env_app
-
-# The Gateway App
-app = FastAPI(title="PR Review Gateway")
-
-# 1. Mount Environment API Routes (Primary for OpenEnv Validator)
-# These will be available on the main port 7860
-app.include_router(env_app.router)
-
-# 2. Proxy for Streamlit Dashboard (Internal port 8501)
-STREAMLIT_URL = "http://localhost:8501"
-client = httpx.AsyncClient(base_url=STREAMLIT_URL)
-
-@app.api_route("/{path:path}", methods=["GET", "POST", "PUT", "DELETE", "OPTIONS", "HEAD", "PATCH"])
-async def proxy_to_streamlit(request: Request, path: str):
-    """
-    Catch-all route to proxy everything else to the Streamlit dashboard on port 8501.
-    """
-    url = f"{STREAMLIT_URL}/{path}"
-    
-    # Forward the request headers and body
-    headers = dict(request.headers)
-    # Remove 'host' to avoid proxy confusion
-    headers.pop("host", None)
-    
-    # Handle Streamlit's WebSocket and long-polling if needed
-    # (Note: For full WebSocket support, a more complex proxy is usually needed, 
-    # but for standard Streamlit on HF, this basic forwarder often works for the UI)
-    
-    # Get request body if it exists
-    body = await request.body()
-    
-    # Send request to Streamlit
-    try:
-        response = await client.request(
-            method=request.method,
-            url=url,
-            headers=headers,
-            params=request.query_params,
-            content=body,
-            timeout=30.0
-        )
-        
-        # Return the response back to the user
-        return Response(
-            content=response.content,
-            status_code=response.status_code,
-            headers=dict(response.headers)
-        )
-    except Exception as e:
-        return Response(content=f"Gateway Error: {e}", status_code=502)
-
-if __name__ == "__main__":
-    import uvicorn
-    uvicorn.run(app, host="0.0.0.0", port=7860)

nginx.conf

@@ -0,0 +1,66 @@
+worker_processes 1;
+
+events {
+    worker_connections 1024;
+}
+
+http {
+    include       mime.types;
+    default_type  application/octet-stream;
+    sendfile        on;
+    keepalive_timeout  65;
+
+    map $http_upgrade $connection_upgrade {
+        default upgrade;
+        ''      close;
+    }
+
+    server {
+        listen 7860;
+        server_name localhost;
+
+        # 1. OpenEnv API Endpoints (FastAPI on Port 8000)
+        location /reset {
+            proxy_pass http://localhost:8000/reset;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+        }
+
+        location /step {
+            proxy_pass http://localhost:8000/step;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+        }
+
+        location /health {
+            proxy_pass http://localhost:8000/health;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+        }
+
+        # 2. Streamlit WebSocket (Port 8501)
+        location /_stcore/stream {
+            proxy_pass http://localhost:8501/_stcore/stream;
+            proxy_http_version 1.1;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection "upgrade";
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_read_timeout 86400;
+        }
+
+        # 3. Streamlit UI (Port 8501)
+        location / {
+            proxy_pass http://localhost:8501;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            
+            # Additional Streamlit settings
+            proxy_http_version 1.1;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection $connection_upgrade;
+        }
+    }
+}

start.sh

@@ -1,13 +1,13 @@
 #!/bin/bash
 
+# Start the FastAPI backend on port 8000
+echo "Starting FastAPI Backend on port 8000..."
+uvicorn server.app:app --host 0.0.0.0 --port 8000 &
+
 # Start the Streamlit dashboard internally on port 8501
 echo "Starting Streamlit Dashboard on port 8501..."
 streamlit run app.py --server.port 8501 --server.address 0.0.0.0 --server.headless true &
 
-# Start the FastAPI Gateway on the primary port 7860
-# This gateway handles /reset, /step, and proxies everything else to Streamlit
-echo "Starting FastAPI Gateway on port 7860..."
-uvicorn gateway:app --host 0.0.0.0 --port 7860 &
-
-# Wait for all processes to finish
-wait
+# Start Nginx in the foreground to keep the container alive
+echo "Starting Nginx Proxy on port 7860..."
+nginx -g "daemon off;"