Mysql Database sync between 2 servers

Hello Experts, One of my clients has some odd requirement. He is trying to configure a high availability database structure with Cpanel. His aim to configure a fail over hosting for database. He has got 2 servers and trying to configure the fail over cluster with Haproxy, so far he has done good with HAproxy however the big issue here is Database sync. The client want to sync 1 database on 2 servers ( that are part of the fail over set up ) and if any changes made on server 1 which will be a master server must be synced immediately with the server 2 Can you please suggest any configs, Tools or Tricks here please. Thank you.