What happens to a Kubernetes cluster when 2 of the three masters in a replica set are offline?

5/1/2019

I am trying to figure out the minimum number of kubernetes master nodes in a master replica set for kubernetes that will allow the entire cluster to behave as normal. Their official docs mention that you need a of three master nodes.

What happens when you lose 1 of the 3 master nodes? Can you lose two of the master nodes in a replica set and still have the cluster behave as normal?

-- Dylan
high-availability
kubernetes

1 Answer

5/1/2019

Kubernetes API works as long as Etcd cluster works. Etcd cluster works when there is quorum, so at least 2 of 3 Etcd pods are alive. If only 1 of 3 Etcd pod is alive - cluster goes to read-only state when no new pods can be scheduled and no resource creates/updates/deletes are allowed.

-- Vasily Angapov
Source: StackOverflow