How to close tcp connection by lua when use OR proxy websocket?

As shown below，I used OR to proxy websocket, after switching protocol, the http request finished and websocket continued with the tcp connection. But how can I close the tcp connection actively by lua when I received a singal in anthor http request?

http {
map $http_upgrade $connection_upgrade {
default upgrade;
'' close;
}
upstream websocket {
server localhost:8010;
server localhost:8011;
}
server {
listen 80;
server_name localhost;
access_log /var/log/nginx/yourdomain.log;

location / {
  proxy_pass http://websocket;
  proxy_read_timeout 300s;

  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_http_version 1.1;
  proxy_set_header Upgrade $http_upgrade;
  proxy_set_header Connection $connection_upgrade;
	}
}

}

Start by reviewing the Lua API and the WebSocket proxy behavior shown in the issue configuration, focusing on how a later HTTP request could affect an existing TCP connection. Done means identifying a supported entry point for this cross-request closure or documenting the limitation and its expected behavior.