Foreman HA support guide

Foreman running as a single instance , need HA, please provide information/documentation to achieve it.

Expected outcome:
Foreman HA,

Foreman and Proxy versions:

Foreman and Proxy plugin versions:

Other relevant data:
[e.g. logs from Foreman and/or the Proxy, modified templates, commands issued, etc]
(for logs, surround with three back-ticks to get proper formatting, e.g.)