PodDisruptionBudget
also: PDB
A Kubernetes resource that defines the minimum number or percentage of pod replicas that must remain available during voluntary disruptions like node maintenance or cluster updates.
PodDisruptionBudget (PDB) is a Kubernetes API object that protects application availability by constraining how many pod replicas can be unavailable simultaneously during planned disruptions. It doesn't prevent disruptions—rather, it ensures the cluster respects your availability requirements when performing maintenance.
A PDB specifies either minAvailable (minimum pods that must stay running) or maxUnavailable (maximum pods allowed to be disrupted). For example, a web service with 5 replicas might set minAvailable: 3, guaranteeing at least 3 instances remain running during node drains or updates.
PodDisruptionBudgets apply only to voluntary disruptions like kubectl drain or cluster autoscaling—they don't protect against node failures or resource exhaustion. Kubernetes admission controllers enforce PDBs, preventing evictions that would violate the budget constraints.