Explain the concept of Pod disruption budgets (PDBs) and how they are used to ensure application availability during maintenance.

Pod Disruption Budgets (PDBs) in Kubernetes are a mechanism to ensure that a certain number of Pods for an application remain available, even during voluntary disruptions. Voluntary disruptions include actions initiated by the cluster operator or by an automated process that intends to modify the cluster, such as node maintenance, node draining, or scaling down deployments. PDBs help maintain application availability by limiting the number of Pods that can be simultaneously disrupted. The concept: PDBs define a minimum or maximum number of Pods that must be available for a particular application. When a disruption event occurs, Kubernetes checks the PDBs to ensure that the disruption will not violate the availability requirements defined in the PDBs. If a disruption would violate a PDB, Kubernetes will prevent the disruption from occurring until the PDB can be satisfied. PDBs provide a safety net for applications, ensuring that they remain available even during disruptive events. They are particularly useful for stateful applications or applications that require a minimum number of replicas to maintain performance or availability. How PDBs are used to ensure application availability during maintenance: During maintenance operations, such as node draining or scaling down deployments, Kubernetes respects PDBs to ensure that the maintenance does not cause unacceptable downtime for applications. When a node is drained, Kubernetes attempts to evict the Pods....