How many masters should I use in my HA Kubernetes cluster?


#1

How many masters should I use in my HA Kubernetes cluster? Presumably some of the nodes should be workers, and some masters - what should the distribution be there?


#2

Well, the first part is easy - don’t use two masters. One isn’t exactly highly available, but it’s still better - because while a three master setup can tolerate the loss of one, both two and one master clusters will lose quorum after the first mode dies. This makes two master clusters less reliable than a single master cluster, because there are two nodes for things to go wrong on.

So for a truly HA cluster, three masters. More than this shouldn’t be required at sane cluster sizes, and for small clusters scheduling additional tasks on the master nodes can reduce infrastructure requirements.