In Kubernetes, NoSchedule and NoExecute are two different taint effects used to control pod scheduling and eviction:

🚫 NoSchedule

  • Meaning: Pods will not be scheduled onto the node if they do not tolerate the taint.
  • Already-running pods are not affected.
  • Use case: Prevent new pods from landing on specific nodes (e.g., dedicated nodes for special workloads).

Example:

taints:
- key: "taint"
  value: "special"
  effect: "NoSchedule"

❌ NoExecute

  • Meaning:

    1. Pods will not be scheduled onto the node (like NoSchedule).
    2. Existing pods that do not tolerate the taint will be evicted from the node.

  • Use case: Enforce stricter isolation, e.g., when a node is unhealthy or in maintenance mode.

Example:

taints:
- key: "taint"
  value: "maintenance"
  effect: "NoExecute"

Key Differences

Behavior NoSchedule NoExecute
Blocks scheduling ✅ Yes ✅ Yes
Evicts existing pods ❌ No ✅ Yes
Needs toleration to run ✅ Yes ✅ Yes

Toleration Example (to allow a pod to stay on or be scheduled on a tainted node):

tolerations:
- key: "taint"
  operator: "Equal"
  value: "maintenance"
  effect: "NoExecute"
  tolerationSeconds: 60  # pod will be evicted after 60s

Without tolerationSeconds, the pod will tolerate the taint indefinitely.