matchLabels:

spec:
  podSelector:
    matchLabels:
      app: elasticsearch-master

 apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
 name: zk-pdb
spec:
 minAvailable: 2
 selector:
   matchLabels:
     app: zookeeper

See also

• Kubernetes selectors, PodSelector:, labelSelector:
• Kubernetes labels, selectors, kubectl label, kubectl annotate, Common, kubernetes.io, app.kubernetes.io, MatchLabels: