DevOps

Kubernetes

📄 Reference:

• 📌 kubectl Cheat Sheet
• 📘 Pods Documentation

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Most Used Commands

$ kubectl get pods
$ kubectl run nginx --image=nginx --dry-run=client -o yaml
$ kubectl describe pod 
$ kubectl get pod  -o yaml

🔧 Exercise 1: Working with Pods (Declarative Only)

🎯 Task:

Create a Pod in the default namespace using a YAML file with the following specifications:

• Use any container image of your choice.
• The pod must have 2 containers.
• After applying the YAML, verify that the pod is running.

📂 Solution:

👉 00. Exercises/Pod/Pod.yaml

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🔧 Exercise 2: Expose the App

🎯 Task:

Create a service to expose a Pod in Kubernetes using different service types:

• Create a Pod running an Nginx container that exposes ports 80 and 443.
• Expose the Pod with a NodePort service on port 30007.
• Create a LoadBalancer service that exposes the HTTPS port with TLS passthrough.
• Create another Pod with httpd that shares the same label to demonstrate service selector functionality.

📂 Solution:

👉 00. Exercises/expose-the-app/manifest.yaml - Nginx Pod
👉 00. Exercises/expose-the-app/manifest2.yaml - Apache httpd Pod
👉 00. Exercises/expose-the-app/svc.yaml - NodePort Service
👉 00. Exercises/expose-the-app/svc-lb.yaml - LoadBalancer Service

📚 Key Concepts:

• Services act as stable network endpoints for Pods
• NodePort exposes the service on each node's IP at a static port
• LoadBalancer provisions an external load balancer to route traffic to the service
• Selectors determine which Pods a Service targets based on labels

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🔧 Exercise 3: Ingress from First Principle

🎯 Task:

Implement a multi-service architecture with a custom Nginx-based ingress controller:

• Create separate namespaces for frontend and backend applications
• Deploy a PostgreSQL database
• Deploy a frontend application (httpd) and a backend service (bun)
• Implement a custom Nginx reverse proxy to route requests based on domain names:
  • k8s.rshv.xyz(use your own domain) should route to the backend service
  • k8s2.rshv.xyz(use your own domain) should route to the frontend service

📂 Solution:

👉 00. Exercises/ingress-first-principle/fe.yaml - Frontend Application
👉 00. Exercises/ingress-first-principle/backend.yaml - Backend Application
👉 00. Exercises/ingress-first-principle/db.yaml - Database Deployment
👉 00. Exercises/ingress-first-principle/reverse-proxy.yaml - Custom Nginx Ingress

📚 Key Concepts:

• Namespaces provide isolation between different application components
• ConfigMaps store configuration data like Nginx configuration
• Service Discovery using Kubernetes DNS (servicename.namespace.svc.cluster.local)
• Custom Ingress Controller using Nginx reverse proxy for domain-based routing

🔧 Exercise 4: Kubernetes Native Ingress

🎯 Task:

Implement path-based routing using Kubernetes native Ingress resources:

• Deploy two applications: a backend using Nginx and a frontend using Apache httpd
• Create ClusterIP services for both applications
• Configure a Kubernetes Ingress resource to route traffic based on URL paths:
  • /backend path should route to the backend service
  • /frontend path should route to the frontend service
• Use annotations to configure URL rewriting

📂 Solution:

👉 00. Exercises/ingress/manifest-be.yaml - Backend Deployment and Service
👉 00. Exercises/ingress/manifest-fe.yaml - Frontend Deployment and Service
👉 00. Exercises/ingress/ingress.yaml - Ingress Resource

📚 Key Concepts:

• Ingress Resources provide HTTP/HTTPS routing, path-based routing, and name-based virtual hosting
• IngressClass specifies which controller should implement the Ingress
• Path Types define how paths are matched (Prefix, Exact, ImplementationSpecific)
• Annotations configure controller-specific behaviors like URL rewriting
• Ingress Controller is the component that actually implements the Ingress rules (typically Nginx)

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HELM

Cheat Sheet

// Install a chart from a local directory
helm create mychart
helm install mychartrelease mychart

// Uninstall a release
helm uninstall mychartrelease

// List releases
helm list -a

// upgrade the the helm chart
helm upgrade mychartrelease mychart

// rollback to a previous version
helm rollback mychartrelease 1

// debug
helm install --dry-run --debug mychartrelease mychart

// helm template
helm template mychart


// helm lint
helm lint mychart