Today's article is an item I covered briefly during my presentation at SaltConf 2014 (which was a pretty awesome conference by the way). One of the lesser known features of SaltStack is the ability to configure multiple master servers. Having an additional master server allows for some extra redundancy as well as capacity for large implementations. While I covered the benefits of having an additional master server in my presentation I didn't cover in full detail how to set this up, today I will cover the details of configuring multiple salt masters.
How SaltStack multi-master works
SaltStack's multiple master configuration is actually a pretty simple implementation. The master servers do not require any communication or heartbeats between each other, both servers are simply online at the same time. This allows minions to communicate to either master server without any special DNS or IP fail-over mechanisms. The only prerequisite is that the two masters must share the same public/private keys.