Kubernetes Hands-On Lab

Deploy your first application to Kubernetes

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Your Progress

  • Verify prerequisites are installed
  • Explore and understand the project files
  • Build the Docker image
  • Deploy to Kubernetes
  • Verify deployment is running
  • Access the application in browser
0

Prerequisites

Before starting, make sure you have the following set up:

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Run these commands to verify everything is working:
# Check Docker is installed and running docker --version # Check kubectl is available kubectl version --client # Verify Kubernetes cluster is running kubectl cluster-info # Check nodes are ready kubectl get nodes
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Expected: All commands should run without errors. You should see version numbers and cluster information.
1

Open Docker Desktop

Look for the whale icon in your system tray/menu bar. It should be running (not showing any errors).

2

Check Kubernetes is Enabled

Click the gear icon (⚙️) → Kubernetes → Ensure "Enable Kubernetes" is checked.

3

Verify Green Status

In the bottom-left corner, you should see both Docker (whale) and Kubernetes (ship wheel) icons in green.

⏳
If you just enabled Kubernetes, it may take 2-5 minutes to start. Wait for the green status indicator.
1

Explore the Project

First, let's understand what files we're working with:

📁 k8s-lab/
├── 📁 app/
├── 📄 index.html ← Frontend interface
└── 📄 game.js ← Application logic
├── 📁 manifests/
├── 📄 deployment.yaml ← Kubernetes Deployment
└── 📄 service.yaml ← Kubernetes Service
└── 🐳 Dockerfile ← Container build instructions

The Dockerfile creates a container image that:

  • Uses nginx:alpine as the base (a lightweight web server)
  • Copies our application files into the nginx web directory
  • Exposes port 80 for web traffic
FROM nginx:alpine COPY app/ /usr/share/nginx/html/ EXPOSE 80

The Deployment tells Kubernetes to:

  • Run 2 replicas (copies) of our application
  • Use the image we build (lab-app:v1)
  • Set resource limits for CPU and memory
  • Automatically restart pods if they fail

The Service exposes our application to the network:

  • Type NodePort makes it accessible from your machine
  • Routes traffic to pods with label app: lab-app
  • Exposes the app on port 30080
2

Build the Docker Image

Navigate to the project directory and build the image:

# Navigate to the lab directory cd k8s-lab # Build the Docker image docker build -t lab-app:v1 .
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The -t lab-app:v1 tags the image with name "lab-app" and version "v1". The . tells Docker to use the current directory.

Verify the image was created:

docker images | grep lab-app
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Expected output:
lab-app v1 abc123def 10 seconds ago 45MB
⚠️
Docker Desktop doesn't have a GUI for building images. You'll need to use the terminal for this step, but you can verify the result in the GUI.
1

Open Terminal

Open Terminal (Mac/Linux) or PowerShell/Command Prompt (Windows)

2

Run the Build Command

cd k8s-lab && docker build -t lab-app:v1 .
3

Verify in Docker Desktop

Open Docker Desktop → Click "Images" in the left sidebar → You should see lab-app with tag v1

3

Deploy to Kubernetes

Apply the Kubernetes manifests to create your resources:

# Create the Deployment (runs your app pods) kubectl apply -f manifests/deployment.yaml # Create the Service (exposes your app) kubectl apply -f manifests/service.yaml
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Expected output:
deployment.apps/lab-app created
service/lab-app-service created
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Pro tip: You can also apply all manifests at once:
kubectl apply -f manifests/
1

Open Terminal and Apply Manifests

Docker Desktop's Kubernetes doesn't have a GUI for applying manifests, so we'll use kubectl:

kubectl apply -f manifests/
2

View in Docker Desktop

Open Docker Desktop → Click "Containers" → Look for containers with lab-app in the name

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While Docker Desktop shows running containers, the best way to manage Kubernetes resources is through kubectl commands.
4

Verify Your Deployment

Check that all resources are running correctly:

# Check the Deployment status kubectl get deployments # Check the Pods (should show 2 running) kubectl get pods # Check the Service kubectl get services
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What to look for:
  • Deployment: READY 2/2
  • Pods: Both showing Running with 1/1 ready
  • Service: Type NodePort with port 30080

Watch pods start up in real-time:

# Watch until pods are Running (Ctrl+C to stop) kubectl get pods -w
1

Open Docker Desktop

Click on "Containers" in the left sidebar

2

Find Your Pods

Look for containers named k8s_lab-app_lab-app-xxxxx. You should see 2 of them (for 2 replicas).

3

Check Status

Each container should show a green "Running" status

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Click on a container to see its logs, inspect details, or open a terminal inside it.
5

Access Your Application

🎉 Congratulations!

If all steps completed successfully, your application is now running!

Open http://localhost:30080

Click the link above or paste the URL in your browser

⚠️
Not working? Check the Troubleshooting section below!
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Troubleshooting

Symptoms: kubectl get pods shows status other than "Running"

Solution

Get more details about the pod:

# Get pod name first kubectl get pods # Describe the pod (replace with actual name) kubectl describe pod lab-app-xxxxxx

Look at the Events section at the bottom for error messages.

Symptoms: Pod status shows "ImagePullBackOff" or "ErrImagePull"

Cause: Kubernetes can't find the Docker image

Solution

1. Verify the image exists locally:

docker images | grep lab-app

2. If the image doesn't exist, rebuild it:

docker build -t lab-app:v1 .

3. Make sure you're in the k8s-lab directory when building!

Symptoms: Browser shows "connection refused" or "site can't be reached"

Solution

1. Check pods are running:

kubectl get pods

2. Check service exists and has correct port:

kubectl get services

3. Check service has endpoints (should show pod IPs):

kubectl get endpoints lab-app-service

4. If endpoints are empty, check pod labels match service selector.

Symptoms: kubectl commands return errors about connection or server

Solution (Docker Desktop)

1. Open Docker Desktop Settings (gear icon)

2. Go to Kubernetes

3. Ensure "Enable Kubernetes" is checked

4. If already checked, click "Reset Kubernetes Cluster"

5. Wait for the Kubernetes icon to turn green

Symptoms: Service can't start or port conflict error

Solution

1. Find what's using the port:

# Mac/Linux lsof -i :30080 # Windows netstat -ano | findstr :30080

2. Either stop that process, or edit service.yaml to use a different nodePort (30000-32767)

Logs help debug application issues:

# View logs for a specific pod kubectl logs lab-app-xxxxxx # Follow logs in real-time kubectl logs -f lab-app-xxxxxx # View logs for all pods with a label kubectl logs -l app=lab-app

To delete everything and start fresh:

# Delete Kubernetes resources kubectl delete -f manifests/ # Delete the Docker image docker rmi lab-app:v1 # Verify cleanup kubectl get all docker images | grep lab-app
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Bonus Challenges

Completed the lab? Try these challenges to deepen your Kubernetes knowledge:

Increase the number of pod replicas:

# Scale to 4 replicas kubectl scale deployment lab-app --replicas=4 # Watch pods scale up kubectl get pods -w # Scale back down kubectl scale deployment lab-app --replicas=2

Open a shell inside a running container:

# Get pod name kubectl get pods # Open shell in pod (replace xxxxx) kubectl exec -it lab-app-xxxxx -- /bin/sh # Inside the container, explore: ls /usr/share/nginx/html cat /etc/nginx/nginx.conf exit

Update your application with zero downtime:

# Make a change to app/index.html # Then build a new version docker build -t lab-app:v2 . # Update the deployment kubectl set image deployment/lab-app lab-app=lab-app:v2 # Watch the rolling update kubectl rollout status deployment/lab-app # Rollback if needed kubectl rollout undo deployment/lab-app

Monitor CPU and memory usage:

# View pod resource usage kubectl top pods # View node resource usage kubectl top nodes # Describe pod to see resource limits kubectl describe pod lab-app-xxxxx | grep -A 5 "Limits\|Requests"
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Note: kubectl top requires the metrics-server to be installed. In Docker Desktop, this may need to be enabled separately.
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Quick Reference - Essential Commands

# --- Viewing Resources --- kubectl get pods # List all pods kubectl get deployments # List all deployments kubectl get services # List all services kubectl get all # List everything # --- Detailed Information --- kubectl describe pod [name] # Pod details & events kubectl logs [pod-name] # View pod logs kubectl logs -f [pod-name] # Stream logs live # --- Managing Resources --- kubectl apply -f [file] # Create/update resource kubectl delete -f [file] # Delete resource kubectl scale deployment [name] --replicas=N # --- Debugging --- kubectl exec -it [pod] -- /bin/sh # Shell into pod kubectl get events # View cluster events