Track server open connection

Question

I've configured my web server using NestJS with a keep-alive time of 65 seconds and a header timeout of 67 seconds like this:

  const server = await app.listen(appPort, appHost);
  server.keepAliveTimeout = 65 * 1000;
  server.headersTimeout = 67 * 1000;

Additionally, I've enabled keep-alive when making HTTP requests to this server from other NestJS servers. Now, I'd like to monitor and keep track of the number of open connections to my web server.