nginx.conf

events {
    # Maximum number of simultaneous connections
    worker_connections 1024;
}

http {
    map $http_upgrade $connection_upgrade {
        default upgrade;
        '' close;
    }

    # Upstream definition for HAProxy RPC load balancer
    upstream rpc_nodes {
        server 127.0.0.1:8545;
    }

    upstream ws_nodes {
        server 127.0.0.1:8546;
    }

    server {
        listen 8080;

        # Main location for RPC traffic
        location / {
            # Remove any existing CORS headers from upstream
            proxy_hide_header 'Access-Control-Allow-Origin';
            proxy_hide_header 'Access-Control-Allow-Methods';
            proxy_hide_header 'Access-Control-Allow-Headers';
            proxy_hide_header 'Access-Control-Max-Age';
            
            # Handle preflight requests
            if ($request_method = 'OPTIONS') {
                add_header 'Access-Control-Allow-Origin' '*';
                add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
                add_header 'Access-Control-Allow-Headers' 'Content-Type';
                add_header 'Access-Control-Max-Age' 1728000;
                add_header 'Content-Type' 'text/plain; charset=utf-8';
                add_header 'Content-Length' 0;
                return 204;
            }

            # Add CORS headers for non-OPTIONS requests
            if ($request_method != 'OPTIONS') {
                add_header 'Access-Control-Allow-Origin' '*';
                add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
                add_header 'Access-Control-Allow-Headers' 'Content-Type';
            }

            # WebSocket specific configuration
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection $connection_upgrade;

            # Route WebSocket traffic to ws_nodes, regular traffic to rpc_nodes
            if ($http_upgrade = "websocket") {
                proxy_pass http://ws_nodes;
            }

            proxy_pass http://rpc_nodes;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }

        # Health check endpoint for Kubernetes/monitoring
        # Liveness probe endpoint - always returns OK
        location /health/alive {
            access_log off;
            return 200 "OK";
            add_header Content-Type text/plain;
        }

        # Readiness probe endpoint - always returns OK
        location /health/ready {
            access_log off;
            # Short timeouts for quick health check responses
            proxy_connect_timeout 2s;
            proxy_read_timeout 2s;
            proxy_pass http://127.0.0.1:8547/health;
            add_header Content-Type text/plain;
        }
    }
}