Keepalived has three components that supports active-passive high-availability setup which are:
The daemon for Linux servers.
Ensuring services remain online even in the event of server failures by implementing Virtual Router Redundancy Protocol (VRRP) wherein backup node listens for VRRP advertisement packets from the primary node, if it does not receive, the backup node takes over as primary and assigns the configured VIPs to itself.
Configured number of health-checks for primary node failures keepalived reassigns virtual IP address from primary node to passive node.
The main goal of this project is to provide simple and robust facilities for load balancing and high-availability Linux based infrastructures.