Pod priority and preemption in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is pod priority in Kubernetes?

Pod priority is a value assigned to pods that indicates their importance. Higher priority pods are scheduled before lower priority ones when resources are limited.

beginner

What does preemption mean in the context of Kubernetes pods?

Preemption means Kubernetes can evict (remove) lower priority pods to free resources for higher priority pods that need to be scheduled.

intermediate

How do you assign a priority to a pod?

You assign a priority by specifying a priorityClassName in the pod's spec, which refers to a PriorityClass resource defining the priority value.

intermediate

What happens if a high priority pod cannot be scheduled due to lack of resources?

Kubernetes tries to preempt lower priority pods by evicting them to free resources so the high priority pod can be scheduled.

advanced

Can preemption cause disruption to running applications?

Yes, preemption evicts pods which can cause temporary downtime or disruption for those lower priority applications.

What does the priorityClassName field in a pod spec do?

A Specifies the container image version

B Defines the namespace of the pod

C Assigns a priority to the pod for scheduling decisions

D Sets the pod's resource limits

priorityClassName links the pod to a PriorityClass resource that sets its scheduling priority.

What triggers preemption in Kubernetes?

A A node goes offline

B A pod exceeds its CPU limits

C A pod crashes repeatedly

D A high priority pod cannot be scheduled due to insufficient resources

Preemption happens when a high priority pod needs resources but none are free, so lower priority pods are evicted.

Which of these is true about pod priority values?

A Higher values mean higher priority

B Lower values mean higher priority

C Priority values must be between 0 and 10

D Priority values are assigned randomly

In Kubernetes, higher numeric priority values indicate higher importance.

What happens to a pod that is preempted?

A It is evicted and terminated to free resources

B It is paused and resumed later

C It is moved to another node automatically

D It continues running without changes

Preempted pods are evicted and terminated to make room for higher priority pods.

Can a pod with no priorityClassName be preempted?

A No, it cannot be preempted

B Yes, it has the lowest priority by default

C Only if it requests more than 1 CPU

D Only if it is in a special namespace

Pods without a priorityClassName get the lowest priority and can be preempted by any pod with a priority.

Explain how pod priority and preemption work together in Kubernetes scheduling.

Think about how Kubernetes decides which pods run when resources are tight.

Describe the impact of preemption on running applications and how to manage it.

Consider what happens when a pod is removed to make space for another.