Vertical Pod Autoscaler concept in Kubernetes - Mini Project: Build & Apply

Vertical Pod Autoscaler Concept

📖 Scenario: You are managing a Kubernetes cluster that runs a web application. You want to automatically adjust the CPU and memory resources of your pods based on their usage to keep the application running smoothly without wasting resources.

🎯 Goal: Learn how to create a Vertical Pod Autoscaler (VPA) resource in Kubernetes to automatically adjust pod resource requests and limits.

📋 What You'll Learn

Create a basic pod specification with resource requests

Define a Vertical Pod Autoscaler configuration targeting the pod

Apply the VPA to the pod to enable automatic resource adjustment

Verify the VPA status and recommendations

💡 Why This Matters

🌍 Real World

Vertical Pod Autoscaler helps keep applications running efficiently by automatically adjusting pod CPU and memory based on actual usage, avoiding manual tuning.

💼 Career

Understanding VPA is important for Kubernetes administrators and DevOps engineers to optimize resource usage and maintain application performance.

1

Create a pod manifest with resource requests

Create a YAML manifest file named web-pod.yaml that defines a pod called web-app running the image nginx:latest. Set the CPU request to 100m and memory request to 200Mi under resources.requests.

Kubernetes

# Create a pod manifest with name web-app and resource requests
# Your code here

Hint

Use resources.requests.cpu and resources.requests.memory fields inside the container spec.

2

Create a Vertical Pod Autoscaler configuration

Create a YAML manifest file named vpa.yaml that defines a Vertical Pod Autoscaler resource called web-app-vpa. Set the target reference to the pod named web-app and set the update policy to Auto.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: web-app
spec:
  containers:
  - name: nginx-container
    image: nginx:latest
    resources:
      requests:
        cpu: "100m"
        memory: "200Mi"

# Create a Vertical Pod Autoscaler manifest named web-app-vpa targeting web-app pod
# Your code here

Hint

Use spec.targetRef to point to the pod and spec.updatePolicy.updateMode to set automatic updates.

3

Apply the pod and VPA manifests to the cluster

Use the kubectl apply -f command to apply both web-pod.yaml and vpa.yaml files to your Kubernetes cluster.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: web-app
spec:
  containers:
  - name: nginx-container
    image: nginx:latest
    resources:
      requests:
        cpu: "100m"
        memory: "200Mi"
---
apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: web-app-vpa
spec:
  targetRef:
    apiVersion: v1
    kind: Pod
    name: web-app
  updatePolicy:
    updateMode: "Auto"

# Apply the manifests using kubectl
# Your code here

Hint

Run kubectl apply -f for each YAML file to create resources.

4

Check the VPA status and recommendations

Run the command kubectl describe vpa web-app-vpa to see the current status and resource recommendations made by the Vertical Pod Autoscaler.

Kubernetes

kubectl apply -f web-pod.yaml
kubectl apply -f vpa.yaml

# Run kubectl describe to check VPA status
# Your code here

Hint

This command shows the VPA's current recommendations for CPU and memory.

Practice

1. What is the main purpose of the Vertical Pod Autoscaler in Kubernetes?

easy

A. Schedule pods to specific nodes manually

B. Scale the number of pod replicas up or down

C. Manage network policies between pods

D. Automatically adjust CPU and memory requests for pods based on usage

Solution

1. Step 1: Understand VPA's role

   The Vertical Pod Autoscaler changes resource requests (CPU, memory) for pods automatically based on their usage.

2. Step 2: Differentiate from other autoscalers

   Unlike Horizontal Pod Autoscaler, which changes pod count, VPA adjusts resource limits inside pods.

3. Final Answer:

   Automatically adjust CPU and memory requests for pods based on usage -> Option D

4. Quick Check:

   VPA adjusts resources, not pod count [OK]

Hint: VPA changes pod resources, not pod numbers [OK]

Common Mistakes:

• Confusing VPA with Horizontal Pod Autoscaler
• Thinking VPA manages pod replicas
• Assuming VPA controls networking

2. Which of the following is the correct YAML snippet to create a Vertical Pod Autoscaler targeting a deployment named my-app?

easy

A. apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
name: my-app-hpa
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: my-app

B. apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
name: my-app-vpa
spec:
targetRef:
apiVersion: apps/v1
kind: Deployment
name: my-app

C. apiVersion: v1
kind: Pod
metadata:
name: my-app-pod
spec:
containers:
- name: my-app
image: my-app-image

D. apiVersion: autoscaling.k8s.io/v2
kind: VerticalPodAutoscaler
metadata:
name: my-app-vpa
spec:
target:
apiVersion: apps/v1
kind: Deployment
name: my-app

Solution

1. Step 1: Check apiVersion and kind

   Correct VPA uses apiVersion: autoscaling.k8s.io/v1 and kind: VerticalPodAutoscaler.

2. Step 2: Verify targetRef structure

   The targetRef field must specify the deployment with apiVersion, kind, and name correctly.

3. Final Answer:

   YAML with apiVersion autoscaling.k8s.io/v1, kind VerticalPodAutoscaler, and targetRef for my-app deployment -> Option B

4. Quick Check:

   VPA YAML uses targetRef, autoscaling.k8s.io/v1 [OK]

Hint: VPA uses targetRef, not scaleTargetRef [OK]

Common Mistakes:

• Using HorizontalPodAutoscaler instead of VerticalPodAutoscaler
• Wrong apiVersion like autoscaling/v1
• Incorrect field name target instead of targetRef

3. Given this VPA configuration snippet, what will happen when the pod's CPU usage increases beyond the current request?

apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: example-vpa
spec:
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: example-app
  updatePolicy:
    updateMode: "Auto"

medium

A. The VPA will automatically update the pod's CPU requests to match usage

B. The pod replicas will increase to handle the load

C. The pod will restart immediately to apply new resources

D. Nothing happens until manual intervention

Solution

1. Step 1: Understand updateMode Auto

   When updateMode is Auto, VPA automatically adjusts resource requests without manual steps.

2. Step 2: Effect on pod resources

   VPA changes CPU and memory requests to match observed usage, improving stability and efficiency.

3. Final Answer:

   The VPA will automatically update the pod's CPU requests to match usage -> Option A

4. Quick Check:

   updateMode Auto means automatic resource adjustment [OK]

Hint: Auto updateMode means VPA adjusts resources automatically [OK]

Common Mistakes:

• Confusing VPA with Horizontal Pod Autoscaler scaling pods
• Thinking pods restart immediately on resource change
• Assuming manual approval is needed with Auto mode

4. You applied a Vertical Pod Autoscaler with updateMode: Auto, but pod resource requests did not change after high CPU usage. What is a likely cause?

medium

A. The Horizontal Pod Autoscaler is overriding VPA settings

B. The pod replicas are too few to trigger scaling

C. The VPA targetRef is incorrect or does not match the pods

D. The pod image version is outdated

Solution

1. Step 1: Check VPA targetRef correctness

   If targetRef does not correctly point to the pods or deployment, VPA cannot adjust resources.

2. Step 2: Understand VPA scope

   VPA only adjusts resources for pods matching targetRef; replicas count or pod image do not affect resource updates directly.

3. Final Answer:

   The VPA targetRef is incorrect or does not match the pods -> Option C

4. Quick Check:

   Incorrect targetRef means no resource updates [OK]

Hint: Verify targetRef matches pods exactly [OK]

Common Mistakes:

• Blaming pod replicas count for resource update failure
• Assuming HPA conflicts with VPA resource updates
• Thinking pod image version affects VPA behavior

5. You want to use Vertical Pod Autoscaler but avoid pod restarts during resource updates. Which updateMode should you choose and why?

hard

A. "Initial" to set resources only at pod creation without restarts later

B. "Auto" to update resources and restart pods automatically

C. "Off" to disable updates and avoid restarts

D. "Manual" to require manual approval before updates

Solution

1. Step 1: Understand updateMode options

   "Off" disables updates, "Auto" updates and restarts pods, "Initial" sets resources only at pod start, "Manual" requires manual approval.

2. Step 2: Choose mode to avoid restarts

   "Initial" mode applies resource recommendations only when pods start, so no restarts happen later.

3. Final Answer:

   "Initial" to set resources only at pod creation without restarts later -> Option A

4. Quick Check:

   Initial mode avoids restarts by updating only at pod start [OK]

Hint: Use Initial mode to avoid pod restarts on resource changes [OK]

Common Mistakes:

• Choosing Off disables VPA completely
• Assuming Manual mode avoids restarts automatically
• Confusing Auto mode with no restarts