HAProxy
Some useful links to explain the concepts of HAProxy
Concepts
Official Documentation
Configuration
https://serversforhackers.com/using-ssl-certificates-with-haproxy
https://cbonte.github.io/haproxy-dconv/configuration-1.5.html
http://ubtutorials.com/tutorial/436/how-implement-ssl-termination-haproxy-ubuntu-1404
https://www.howtoforge.com/high-availability-load-balancer-haproxy-heartbeat-debian-etch
http://support.severalnines.com/entries/23612682-Install-HAProxy-and-Keepalived-Virtual-IP-
http://behindtheracks.com/2014/04/redundant-load-balancers-haproxy-and-keepalived/
https://marc.cortinasval.cat/blog/2013/12/04/a-cheap-web-balancer-nginxhaproxypacemaker/
http://support.severalnines.com/entries/23612682-Install-HAProxy-and-Keepalived-Virtual-IP-