k8s/docker-desktop-k8s-setup.md

Docker Desktop + Kubernetes Setup for Warbler CDA

Since you're using Docker, you can test the Kubernetes deployment locally using Docker Desktop's built-in Kubernetes feature.

Prerequisites

1. Enable Kubernetes in Docker Desktop:

   • Open Docker Desktop
   • Go to Settings → Kubernetes
   • Check "Enable Kubernetes"
   • Apply & Restart

2. Verify Kubernetes is running:

   kubectl cluster-info
   kubectl get nodes
   

Quick Start with Docker Desktop K8s

Option 1: Use the deployment script

cd k8s
./deploy.sh

Option 2: Manual deployment

1. Build and load image directly to Docker Desktop:

# Build the image
docker build -t warbler-cda:latest .

# The image is now available to K8s since Docker Desktop shares images

2. Deploy to local Kubernetes:

cd k8s
kubectl apply -f .

3. Check deployment:

kubectl get pods -n warbler-cda
kubectl get svc -n warbler-cda
kubectl get ingress -n warbler-cda

4. Access the application:

Option A: Use port-forwarding (recommended for development)

kubectl port-forward svc/warbler-cda-service 8001:80 -n warbler-cda

Then visit: http://localhost:8001/health

Option B: Access via Ingress (requires ingress controller)

First, enable ingress in Docker Desktop and install NGINX Ingress:

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.8.1/deploy/static/provider/cloud/deploy.yaml

Then update your ingress.yaml to use a local domain or use port forwarding.

Compare: Docker Compose vs Kubernetes

Feature	Docker Compose	Kubernetes
Scaling	Manual replica adjustment	Auto-scaling, rolling updates
Networking	Simple service discovery	Complex service mesh
Storage	Local volumes	Persistent volumes, storage classes
Health Checks	Basic	Liveness/readiness probes
Resource Limits	Basic	Detailed QoS, limits/requests
Environment	Single host	Multi-node clusters

Local Development Workflow

1. Develop with Docker Compose (faster iteration):

   docker-compose up --build
   

2. Test production deployment with Kubernetes:

   cd k8s && ./deploy.sh
   kubectl port-forward svc/warbler-cda-service 8001:80 -n warbler-cda
   

3. Debug if needed:

   kubectl logs -f deployment/warbler-cda -n warbler-cda
   kubectl describe pod -n warbler-cda
   

Benefits of Docker Desktop Kubernetes

• Same deployment as production - test your exact K8s manifests
• Resource isolation - proper containerization like production
• Networking simulation - test service communication
• Storage testing - validate PVC behavior
• Health check validation - ensure probes work correctly

Troubleshooting Docker Desktop K8s

Common issues:

1. "ImagePullBackOff" error:

   • Make sure you built the image: docker build -t warbler-cda:latest .
   • Update deployment.yaml image to warbler-cda:latest

2. PVC pending:

   • Docker Desktop K8s has storage classes, but storage might not provision immediately
   • Check: kubectl get pvc -n warbler-cda
   • You can use hostPath storage for local testing

3. Ingress not working:

   • Install ingress controller first
   • Use port-forwarding for simpler local access

4. Resource constraints:

   • Docker Desktop K8s shares resources with Docker
   • Reduce resource requests in deployment.yaml if needed

Converting Docker Compose to Kubernetes

Your docker-compose.yml has been converted to K8s with these mappings:

Docker Compose	Kubernetes Equivalent
image: .	deployment.yaml with image build step
ports: - "8001:8000"	service.yaml + ingress.yaml
environment:	configmap.yaml + envFrom
volumes: ./data:/app/data	pvc.yaml + volumeMounts
restart: unless-stopped	Deployment with replicas

The Kubernetes setup provides production-grade features while maintaining the same application behavior as your Docker Compose setup.