nginx.conf

server {
    listen 80;

    server_name localhost;
    
    # Enhanced security headers
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;

    # Root directory for static files
    root /usr/share/nginx/html;
    index index.html;

    # Static file serving with optimized caching
    location / {
        try_files $uri $uri/ /index.html;

        # Disable caching for HTML to always check for updates
        location ~* \.html$ {
            expires -1;
            add_header Cache-Control "no-store, no-cache, must-revalidate";
        }
        
        # Cache bust other static assets with query strings or file hashes
        location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
            expires 1y;
            add_header Cache-Control "public, immutable";
        }
        
        # Optimize static file serving
        tcp_nodelay on;
        tcp_nopush on;
        sendfile on;
        
        # Gzip compression for static files
        gzip on;
        gzip_types text/plain text/css application/javascript application/json image/svg+xml;
        gzip_min_length 1000;
    }

    # WebSocket proxy with optimized settings
    location /ws {
        proxy_pass http://app:3001;
        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_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # WebSocket timeouts
        proxy_read_timeout 300s;
        proxy_connect_timeout 75s;
        proxy_send_timeout 300s;
        
        # WebSocket specific optimizations
        proxy_buffering off;
        proxy_cache off;
    }

    # Drawing endpoint proxy with optimized settings
    location /drawing.bmp {
        proxy_pass http://app:3001;
        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;
        
        # Since this is real-time generated content
        proxy_buffering off;
        proxy_cache off;
        expires -1;
        add_header Cache-Control "no-store, no-cache, must-revalidate";
    }

    # Health check endpoint proxy
    location /health {
        proxy_pass http://app:3001;
        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;
        
        # Optimize for health checks
        proxy_buffering off;
        proxy_cache off;
        expires -1;
        add_header Cache-Control "no-store, no-cache, must-revalidate";
    }

    # Deny access to . files
    location ~ /\. {
        deny all;
        access_log off;
        log_not_found off;
    }
}