Horizontal Pod Autoscaler in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Horizontal Pod Autoscaler (HPA) in Kubernetes?

HPA automatically adjusts the number of pods in a deployment or replica set based on observed CPU utilization or other select metrics to keep applications running smoothly.

beginner

Which metric is most commonly used by HPA to scale pods?

CPU utilization is the most common metric used by HPA to decide when to add or remove pods.

intermediate

What command creates a Horizontal Pod Autoscaler for a deployment named 'webapp' targeting 50% CPU usage?

kubectl autoscale deployment webapp --cpu-percent=50 --min=1 --max=5

beginner

What happens if the CPU usage goes above the target set in HPA?

HPA increases the number of pods to distribute the load and reduce CPU usage per pod.

intermediate

Can Horizontal Pod Autoscaler scale based on custom metrics other than CPU?

Yes, HPA can scale pods based on custom metrics like memory usage, request rate, or any metric exposed via the Kubernetes metrics API.

What does Horizontal Pod Autoscaler adjust in Kubernetes?

A Number of pods

B Pod CPU speed

C Node count

D Container image version

HPA changes the number of pods to handle load, not CPU speed or nodes.

Which command creates an HPA for deployment 'app' with max 10 pods and target 60% CPU?

A kubectl autoscale deployment app --cpu-percent=60 --min=1 --max=10

B kubectl scale deployment app --cpu=60 --max=10

C kubectl set hpa app --cpu=60 --max=10

D kubectl create hpa app --cpu=60 --max=10

The correct syntax uses 'kubectl autoscale deployment' with --cpu-percent, --min, and --max flags.

If CPU usage is below the target, what does HPA do?

A Increases pods

B Decreases pods

C Restarts pods

D Does nothing

HPA reduces the number of pods to save resources when CPU usage is low.

Which Kubernetes API is required for HPA to get metrics?

A Authentication API

B Storage API

C Networking API

D Metrics API

HPA relies on the Metrics API to fetch CPU and custom metrics.

Can HPA scale pods based on memory usage?

A Only if pods use less than 50% memory

B No, only CPU is supported

C Yes, with custom metrics configured

D Only on nodes with special labels

HPA supports custom metrics like memory if properly configured.

Explain how Horizontal Pod Autoscaler helps maintain application performance in Kubernetes.

Think about how adding or removing pods affects workload handling.

Describe the steps to create and verify a Horizontal Pod Autoscaler for a deployment.

Focus on commands and what you check after creation.