The PodDisruptionBudget kind (or PDB) is used to configure the availability of voluntary disruptions.

To give a little more detail, this is a policy that, for example, limits how many pods can be disrupted at once, this ensure a minimum number of pods remain available during operations such as node upgrade, autoscaling or voluntary evictions. This is a way to ensure serving capacity remains at a given level during upgrades etc.

Here’s an example yaml file for this

apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: echo-pdb
  namespace: dev
spec:
  minAvailable: 1  # At least one pod must be available OR use maxUnavailable: 1 for maximum which can be unavailable
  selector:
    matchLabels:
      app: echo

In this example we use the “minAvailable”, you could use “maxUnavailable” but not both.