There's no such thing as "simple" when it comes to HA setups, the requirements are simply too varied. PostgreSQL has great documentation for their HA featureset, but when it comes to systems-level concerns (detecting that a primary is down and arranging promotion of a replica to primary) you're expected to address those on your own.
With our Galera setup we have a keepalived health check look at the local system, and if it fails/times out it stops sending heart beats so the other sides takes over the vIP. If one system crashes the vIP fails over as well.
