Taints and tolerations in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a taint in Kubernetes?

A taint is a property applied to a node that prevents pods from being scheduled on it unless those pods have matching tolerations.

beginner

What does a toleration do in Kubernetes?

A toleration allows a pod to be scheduled on a node that has matching taints, effectively 'tolerating' the taint.

intermediate

Explain the effect field in a taint.

The effect field defines what happens to pods that do not tolerate the taint. Common effects are NoSchedule (don't schedule), PreferNoSchedule (try not to schedule), and NoExecute (evict existing pods).

intermediate

How do taints and tolerations help in node management?

They help control which pods can run on which nodes, allowing separation of workloads, reserving nodes for special tasks, or isolating nodes for maintenance.

beginner

Give an example of a taint command to prevent pods without tolerations from scheduling on a node named 'worker1'.

kubectl taint nodes worker1 key=value:NoSchedule

What happens if a node has a taint but a pod does not have a matching toleration?

A The pod will ignore the taint and run.

B The pod will be scheduled on that node anyway.

C The pod will be deleted immediately.

D The pod will not be scheduled on that node.

Pods without matching tolerations cannot be scheduled on nodes with taints.

Which effect in a taint causes existing pods without tolerations to be evicted from the node?

A NoExecute

B PreferNoSchedule

C NoSchedule

D Evict

NoExecute evicts existing pods that do not tolerate the taint.

How do you remove a taint from a node named 'node1' with key 'key1' and value 'value1'?

A kubectl taint nodes node1 key1=value1:NoSchedule-

B kubectl remove taint node1 key1=value1

C kubectl delete taint node1 key1=value1

D kubectl clear taint node1 key1=value1

The '-' suffix removes the taint from the node.

Which command adds a toleration to a pod spec?

A kubectl add toleration pod

B Add tolerations field in pod YAML under spec

C kubectl taint pod

D kubectl tolerate pod

Tolerations are added in the pod YAML under the spec section.

What is the main purpose of using taints and tolerations together?

A To delete pods automatically

B To force all pods to run on all nodes

C To control pod scheduling on specific nodes

D To increase pod resource limits

Taints and tolerations control which pods can be scheduled on which nodes.

Describe how taints and tolerations work together to control pod scheduling in Kubernetes.

Think about how nodes can repel pods and how pods can accept that.

Explain the difference between the NoSchedule and NoExecute effects in taints.

Consider when pods are blocked or removed.