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API Deprecation Question Explained (Step by Step).md

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1. Introduction

In this video, you will learn how API deprecation works in Kubernetes and how CKAD tests this concept with practical tasks.​

You will also see how to install and use kubectl convert to migrate old manifests to supported apiVersions using a realistic exam-style example.​

2. What is API Deprecation in Kubernetes?

Kubernetes evolves quickly, so older API versions (like extensions/v1beta1 or apps/v1beta1) are marked as deprecated and later removed.​

When a deprecated API is finally removed in newer cluster versions, manifests using that API will fail to apply, which can break workloads and deployments.​

3. How CKAD Tests API Deprecation

In the CKAD exam, you may receive a YAML manifest using a deprecated apiVersion and be asked to migrate it to a supported version and create the resource successfully.​

Typical examples include Deployments, Ingress, or CronJobs that use beta or legacy APIs that must be converted to their GA counterparts like apps/v1 or batch/v1.​

Common pattern in questions:

“A manifest is stored in /opt/CKAD/deprecated/deploy.yaml using a deprecated API.

Update it to use a supported API version and create the Deployment in the exam namespace.”

4. Installing kubectl and kubectl convert

4.1 Install kubectl

Follow the official Kubernetes instructions to install kubectl for your OS.​

Example for Linux (binary download):

curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
chmod +x kubectl
sudo mv kubectl /usr/local/bin/
kubectl version --client

The Kubernetes documentation provides equivalent commands for macOS and Windows, including package managers like brew, chocolatey, or winget.​

4.2 Install kubectl convert Plugin

From Kubernetes 1.20+, kubectl convert is distributed as a separate plugin under the krew plugin ecosystem or as a standalone binary.​

Option 1: Install via krew

Install krew plugin manager (one-time setup) using the official script.​

Then install the convert plugin:

kubectl krew install convert

Verify:

kubectl convert --help

Option 2: Download from Kubernetes Releases

Download the kubectl-convert binary matching your OS and architecture from the official Kubernetes release artifacts and place it in your PATH.​

Rename it to kubectl-convert (if needed) and ensure it is executable.​

5. CKAD-Style Example Scenario

5.1 Problem Statement (Exam-Style)

“An existing application uses a Deployment manifest stored at /opt/CKAD/deprecated/deploy-nginx.yaml that relies on a deprecated API version.

Update the manifest to use a supported API version and successfully create the Deployment in the ckad namespace.”

This mirrors real exam scenarios where only the apiVersion and related fields need updates, not a full redesign of the resource.​

6. Step-by-Step Demo Using kubectl convert

6.1 Inspect the Original Manifest

cd /opt/CKAD/deprecated
cat deploy-nginx.yaml

Explain on screen:

Show an apiVersion like apps/v1beta1 or extensions/v1beta1.​

Mention that this version is deprecated and removed in modern Kubernetes releases.​

6.2 Run kubectl convert

Use the plugin to convert to a supported version, for example apps/v1:

kubectl convert -f deploy-nginx.yaml --output-version=apps/v1 -o yaml > deploy-nginx-v1.yaml
  • -f deploy-nginx.yaml: Input file.
  • --output-version=apps/v1: Target API version.
  • -o yaml > deploy-nginx-v1.yaml: Save the converted YAML to a new file.

The convert tool updates fields that have changed between versions, such as spec.selector or pod template labels for Deployments.​

6.3 Review the Converted Manifest

cat deploy-nginx-v1.yaml

Explain what to check:

apiVersion should now be apps/v1.

Ensure spec.selector.matchLabels matches template.metadata.labels.​

Emphasize that in CKAD, verifying labels and selectors is important to avoid subtle mistakes that make the Deployment not manage the Pods correctly.​

6.4 Create Namespace (If Required)

If the namespace does not exist:

kubectl create namespace ckad

6.5 Apply the Converted Manifest

kubectl apply -f deploy-nginx-v1.yaml -n ckad

Verify:

kubectl get deploy -n ckad
kubectl get pods -n ckad -o wide

If everything is correct, the Deployment should be created and running using the new API version.​

7. Quick Commands Cheat Sheet (For Viewers)

You can show this on screen or in the video description:

bash

Inspect file

cat /path/to/deprecated.yaml

Convert to supported API version

kubectl convert -f /path/to/deprecated.yaml --output-version=apps/v1 -o yaml > /path/to/new.yaml

Create namespace (if needed)

kubectl create namespace ckad

Apply converted manifest

kubectl apply -f /path/to/new.yaml -n ckad

Verify resources

kubectl get all -n ckad

These steps are directly useful for both CKAD practice and real cluster migrations.​

8. Tips for CKAD Exam

Read the question carefully: Pay attention to file paths, namespaces, and resource names.​

Prefer editing the existing file instead of creating a new one from scratch unless instructed.​

If kubectl convert is not available in the exam environment, use the Kubernetes docs deprecated API migration tables to manually update apiVersion and required fields.​