OP5 Monitor: Load balancer or HAproxy intended for peered master nodes.

Question: 

Is it possible to set-up a load balancer or HAproxy for peered master to ensure WEB-GUI for OP5 users is still accessible in the event that one of the master nodes is not available? 

Answer:

Unfortunately, this is not supported. The main reason is that there is no safeguard against users making incompatible changes on the different servers. The use case for having multiple peers is to safeguard against failures, and to allow checks to continue running while one of the peers is down and/or rebooted for instance.
 
This is why all peers in the cluster should have the capacity to run as a stand-alone master.
 
We always recommend configuring one peer as 'Primary Master'. This should be the machine handling all configuration changes, all API requests, and all day-to-day use. The secondary master(s) would not be used for either configuration or API requests unless the primary master is unavailable for a prolonged period. Some simple dashboards could be set up on the secondary, to allow for some basic UI functionality when the primary goes down.
 
Peered master have dissimilarities such as dashboards, users, permissions and auth backends. Mirroring the configurations is not supported. All objects (hosts, services, host groups, service groups etc.) are being synced between all nodes.

NOTE:  It is however possible that Professional Services can help with a tailor-made solution.