I asked this question on the vfabric forums and received this answer from one of the postgres devs https://communities.vmware.com/thread/455006
I thought i would repost it here in case anyone else finds it useful. I must admit I am finding the lack of documentation around some some horizon features slightly annoying. I will try this on our lab environment and see what happens.
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Since 9.2.4, vPostgres appliance includes some scripts dedicated to this task, making your life far easier. So you don't need to do all those steps manually on the server side. More information here:
Then for managing a switchover to a slave in case of a master failure, JDBC has some basic implementation in its code that has been introduced one year ago with commit 39b085d and you can specify multiple URLs like that:
jdbc:postgresql://host1:port1,host2:port2/test
Connection is chosen in round-robin fashion until success. There is no documentation about that though... I'll ping the jdbc devs to correct that. If you are using an older version of JDBC, you should switch to another solution, like a tomcat layer.