Implement load balancing solution with constraints

Hello mgbee8​ 
you could just create 3 http monitor and configure "master" as a valid response
Each one should have one site's postgress IP as alias IP and alias port 9201
Then assing each monitor to the appropriate k8s pool member

this way only one k8s pool member will be considered active, as the other 2 will fail their monitor.

I assumed that you have one pool with all 3 k8s

if you have 3 different pools you will probably need an irule also to check which pool is active