# maxUnavailable: 1 (m11p5 §4).
#
# Unlike the standalone set (maxUnavailable: 0 — a single node cannot stay
# available across a drain), a 3-voter cluster tolerates losing ONE voter and
# keeps quorum (2 of 3). This PDB lets a node drain/upgrade take at most one pod
# at a time so a voluntary disruption (node drain, autoscaler, rolling upgrade)
# never breaks quorum. It does NOT protect against involuntary loss of two nodes
# at once — spread the pods (topologySpreadConstraints) and keep PVCs durable.
#
# For a cluster scaled beyond 3, maxUnavailable: 1 stays correct (an odd voter
# set of 5/7 tolerates more, but 1-at-a-time is always quorum-safe).
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: tidaldb
  namespace: tidaldb-cluster
  labels:
    app.kubernetes.io/name: tidaldb
    app.kubernetes.io/part-of: tidaldb
spec:
  maxUnavailable: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: tidaldb
      app.kubernetes.io/component: cluster-node