Priority classes for critical workloads in Kubernetes - Mini Project: Build & Apply

Priority classes for critical workloads

📖 Scenario: You are managing a Kubernetes cluster that runs multiple applications. Some applications are critical and must always get resources first when the cluster is busy. To do this, Kubernetes uses PriorityClass objects to assign priority levels to pods.In this project, you will create a priority class for critical workloads and assign it to a pod to ensure it gets scheduled before less important pods.

🎯 Goal: Create a PriorityClass named critical-priority with a high priority value. Then create a pod that uses this priority class. Finally, verify the pod's priority class is set correctly.

📋 What You'll Learn

Create a PriorityClass named critical-priority with value 1000000

Create a pod named critical-pod that uses the critical-priority class

Verify the pod's priority class name is critical-priority

💡 Why This Matters

🌍 Real World

In real Kubernetes clusters, priority classes help ensure that important applications get resources first, especially when the cluster is busy or under resource pressure.

💼 Career

Understanding and using PriorityClasses is essential for Kubernetes administrators and DevOps engineers to manage workload scheduling and maintain application reliability.

1

Create the PriorityClass YAML

Create a YAML manifest named critical-priority.yaml that defines a PriorityClass with the name critical-priority and a value of 1000000. Include a description: "Priority class for critical workloads".

Kubernetes

# Your YAML manifest here

Need a hint?

Use kind: PriorityClass and set metadata.name to critical-priority. The value should be 1000000.

2

Create the Pod YAML with priorityClassName

Create a YAML manifest named critical-pod.yaml that defines a pod with the name critical-pod. Use the critical-priority PriorityClass by setting priorityClassName: critical-priority in the pod spec. Use the nginx image for the container.

Kubernetes

apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
  name: critical-priority
value: 1000000
description: "Priority class for critical workloads"
globalDefault: false
preemptionPolicy: PreemptLowerPriority

# Your pod YAML manifest here

Need a hint?

Set priorityClassName: critical-priority inside the pod spec. Use nginx as the container image.

3

Apply the manifests to the cluster

Run the commands to apply both critical-priority.yaml and critical-pod.yaml to your Kubernetes cluster using kubectl apply -f.

Kubernetes

apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
  name: critical-priority
value: 1000000
description: "Priority class for critical workloads"
globalDefault: false
preemptionPolicy: PreemptLowerPriority
---
apiVersion: v1
kind: Pod
metadata:
  name: critical-pod
spec:
  priorityClassName: critical-priority
  containers:
  - name: nginx
    image: nginx

# Run kubectl apply commands below

Need a hint?

Use kubectl apply -f critical-priority.yaml and kubectl apply -f critical-pod.yaml to apply the manifests.

4

Verify the pod's priority class

Run the command kubectl get pod critical-pod -o jsonpath='{.spec.priorityClassName}' to display the pod's priority class name. This should output critical-priority.

Kubernetes

apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
  name: critical-priority
value: 1000000
description: "Priority class for critical workloads"
globalDefault: false
preemptionPolicy: PreemptLowerPriority
---
apiVersion: v1
kind: Pod
metadata:
  name: critical-pod
spec:
  priorityClassName: critical-priority
  containers:
  - name: nginx
    image: nginx

kubectl apply -f critical-priority.yaml
kubectl apply -f critical-pod.yaml

# Run the command to get the pod's priorityClassName

Need a hint?

Use kubectl get pod critical-pod -o jsonpath='{.spec.priorityClassName}' to check the priority class name.