WebSocket proxying https://nginx.org/en/docs/http/websocket.html
By default, the connection will be closed if the proxied server does not transmit any data within 60 seconds.
Using NGINX as a WebSocket Proxy https://www.nginx.com/blog/websocket-nginx/
The WebSocket protocol is different from the HTTP protocol, but the WebSocket handshake is compatible with HTTP, using the HTTP Upgrade facility to upgrade the connection from HTTP to WebSocket. This allows WebSocket applications to more easily fit into existing infrastructures. For example, WebSocket applications can use the standard HTTP ports 80 and 443, thus allowing the use of existing firewall rules.
Thread pools: implemented graceful exiting of threads. · nginx/nginx@e87a565 https://github.com/nginx/nginx/commit/e87a565aab4da7ade1f016c2bab4371a70998974
By default, the connection will be closed if the proxied server does not transmit any data within 60 seconds. This timeout can be increased with the proxy_read_timeout directive. Alternatively, the proxied server can be configured to periodically send WebSocket ping frames to reset the timeout and check if the connection is still alive.