How does kubernetes guarantee the number of pods in replicaset

Question

Suppose I have a deployment (with replicaset underlying) and set the replica count to 1, how does (or does) kubernetes guarantee there's at most one pod in the cluster?

One corner case is:

• A node cannot talk to controller manager with heartbeat;
• So controller manager considers it dead and updates current replica count to 0 at etcd;
• A new pod is created by controller manager via kubelet, so there're two pods in the cluster.

Answer 1

If you want to make sure that it will first delete the old pod and only then create a new one, you can set the strategy type to Recreate or consider switching to STS instead of Deployment