Descheduling Pods in Kubernetes

Descheduling is the process of evicting Pods from Nodes to rebalance resources or address certain scheduling constraints in a Kubernetes cluster. The descheduler operates after Pods are scheduled, and it helps maintain an optimal distribution of Pods across the cluster based on current state and policies. Kubernetes provides a Descheduler component to perform descheduling, especially when the default scheduler’s placement decisions become suboptimal over time.

Section 1: When to Use Descheduling

The descheduling process is useful in various scenarios:

• Resource Imbalance: When certain Nodes are over-utilized, and others are under-utilized, descheduling can help by evicting and redistributing Pods.
• Node Affinity/Anti-Affinity Violations: If a Pod is no longer adhering to its affinity/anti-affinity rules due to changes in the cluster.
• Topology Spread Constraints Violations: If Pods are no longer evenly spread across Nodes or availability zones.
• Taints and Tolerations Violations: When a Node’s taints have changed and certain Pods should no longer be running on that Node.
• Pod Aging: Evicting older, long-running Pods to allow new Pods to be scheduled.

Section 2: How the Kubernetes…