== With HAProxy ==
Like [https://www.lighttpd.net/ Lighttpd], [http://www.apsis.ch/pound/ Pound], [https://www.ejabberd.im/ Ejabberd] and other servers, [http://www.haproxy.org/ [Load balancer|HAProxy]] expects a single <code>.pem</code> file that has the combined contents of the <code>fullchain.pem</code> and <code>privkey.pem</code>.
Fortunately, certbot offers a --pre-hook, a --post-hook and a --renew-hook that we can use.