I have two hosts, let's call them Host A and Host B. These two hosts run in a VRRP configuration with Host A being the master of Application Instance A and the backup for Application Instance B. Host B is the backup for application instance A and the master for Application B. The configuration files for Application Instance A and B need to be the same on both hosts, and should be kept in sync.

What would be the simplest way to ensure that if a configuration file (say for App instance A) gets updated (irrespective of the host on which it gets update) to be pushed to the other host or at the very least get pulled after a short period or time or even by a cron job/script of sorts.