nginx.conf

limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;

server {
    listen 80;
    server_name _;

    # Security headers on every response
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "DENY" always;

    # Health check — no auth required
    location = /health {
        default_type application/json;
        return 200 '{"status":"ok"}';
    }

    # Chat API — rate-limited, API-key-protected, POST-only
    location = /api/chat {
        limit_req zone=api burst=20 nodelay;
        limit_req_status 429;

        # Validate API key
        if ($http_x_api_key != "${VALID_API_KEY}") {
            return 401 '{"error":"invalid or missing API key"}';
        }

        # Only allow POST
        if ($request_method != POST) {
            return 405 '{"error":"method not allowed"}';
        }

        proxy_pass http://middleware:8000/chat;
        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_connect_timeout 5s;
        proxy_read_timeout 10s;
        proxy_send_timeout 5s;

        default_type application/json;
    }

    # Everything else — 404
    location / {
        default_type application/json;
        return 404 '{"error":"not found"}';
    }
}