NGINX

To use the Xpra html5 client from behind a Nginx proxy, start an xpra server listening on a TCP port, ie:

xpra start :100 --start-child=xterm --bind-tcp=0.0.0.0:10010

And add the following lines to your nginx configuration within a server block:-

server {
  listen        443 ssl http2;
  listen        [::]:443 ssl http2;
  server_name   www.example.com;

  location ^~ /xpra/ {
    proxy_pass       http://127.0.0.1:10010/;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $connection_upgrade;
  }

Make sure to reload the server to update the configuration.

If you are not using the default connect dialog page, you may need to override the "path" option.