README

Pokemon Checker - Kubernetes Learning Project

A simple Kubernetes learning project that displays random Pokemon information using a Go web application. This project demonstrates core Kubernetes concepts through a fun, interactive application.

Project Overview

This project creates a load-balanced web application that:

Fetches and displays random Pokemon data
Shows which pod is serving each request
Demonstrates Kubernetes load balancing in action
Provides hands-on experience with basic Kubernetes operations

Architecture

flowchart TD subgraph "Kubernetes Cluster" LB[Load Balancer Service] subgraph "Pods" P1[Pokemon Pod 1] P2[Pokemon Pod 2] P3[Pokemon Pod 3] end LB --> P1 LB --> P2 LB --> P3 P1 --> PokeAPI[PokeAPI External Service] P2 --> PokeAPI P3 --> PokeAPI end Client[Web Browser] --> LB

Component Flow

sequenceDiagram participant C as Client participant LB as LoadBalancer participant P as Pod participant API as PokeAPI C->>LB: HTTP Request LB->>P: Route to Available Pod P->>API: Fetch Random Pokemon API->>P: Pokemon Data P->>P: Add Pod Info P->>LB: HTTP Response LB->>C: Display Pokemon + Pod ID

Prerequisites

Docker installed
Kubernetes cluster (Minikube, Docker Desktop, or cloud provider)
kubectl configured
Go 1.19 or higher
Docker Hub account

Quick Start

Clone the repository:

bash

git clone [repository-url]
cd pokemon-checker

Deploy the application:

bash

# Make the deployment script executable
chmod +x deploy.sh

# Deploy with your Docker Hub username
./deploy.sh YOUR_DOCKERHUB_USERNAME

Watch the pods in action:

bash

# Get your service URL
kubectl get service pokemon-service

# Watch pod load balancing
while true; do curl -s http://$SERVICE_IP | grep "Pod"; sleep 1; done

Learning Objectives

This project helps you learn:

Basic Kubernetes Concepts:

Pods: Smallest deployable units in Kubernetes
Deployments: Manages the lifecycle of pods
Services: Exposes pods to network traffic
Load Balancing: Distributes traffic across pods
Self-healing: Automatic recovery from failures

Common kubectl Commands:

kubectl get pods: List all pods
kubectl describe pod: Show detailed pod information
kubectl logs: View container logs
kubectl exec: Run commands in containers
kubectl apply: Apply configuration files

Container Management:

Building Docker images
Pushing to registries
Container shells and execution
Log management and debugging

Project Structure

shell

.
├── main.go                 # Go web application
├── Dockerfile             # Container definition
├── deploy.sh             # Deployment script
├── kubernetes/           # Kubernetes configurations
│   ├── deployment.yaml   # Pod deployment configuration
│   └── service.yaml      # Service configuration
├── templates/            # HTML templates
│   └── index.html        # Main page template
└── static/              # Static assets
    └── style.css        # Styles for web interface

Important Files Explained

main.go

Main Go web application
Fetches random Pokemon from PokeAPI
Displays Pokemon information and pod details
Uses HTML templates for rendering

deployment.yaml

yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: pokemon-checker
spec:
  replicas: 2
  selector:
    matchLabels:
      app: pokemon-checker
  template:
    metadata:
      labels:
        app: pokemon-checker
    spec:
      containers:
      - name: pokemon-checker
        image: YOUR_DOCKERHUB_USERNAME/pokemon-checker:latest
        ports:
        - containerPort: 8080

service.yaml

yaml

apiVersion: v1
kind: Service
metadata:
  name: pokemon-service
spec:
  selector:
    app: pokemon-checker
  ports:
    - port: 80
      targetPort: 8080
  type: LoadBalancer

Common Operations

Scale the Deployment

bash

# Increase replicas
kubectl scale deployment pokemon-checker --replicas=5

# Verify scaling
kubectl get pods

View Pod Logs

bash

# Follow logs from all pods
kubectl logs -f -l app=pokemon-checker

# View logs from specific pod
kubectl logs -f pokemon-checker-xyz

Access Container Shell

bash

# Get shell access
kubectl exec -it pokemon-checker-xyz -- sh

# Verify application files
ls /app

Check Pod Status

bash

# Detailed pod information
kubectl get pods -o wide

# Watch pod changes
kubectl get pods -w

Delete and Recreate

bash

# Delete a pod (it will be recreated)
kubectl delete pod pokemon-checker-xyz

# Delete whole deployment
kubectl delete deployment pokemon-checker

Troubleshooting

If pods aren't starting:

Check pod status:

bash

kubectl describe pod pokemon-checker-xyz

View logs:

bash

kubectl logs pokemon-checker-xyz

Verify service:

bash

kubectl get service pokemon-service

Common issues:

ImagePullBackoff: Check Docker Hub credentials and image name
CrashLoopBackOff: Check application logs for errors
Pending: Check cluster resources and node status

Learning Exercises

Scale Exercise:

bash

# Scale to 5 pods
kubectl scale deployment pokemon-checker --replicas=5

# Watch the pods being created
kubectl get pods -w

# Check load balancing
while true; do curl -s http://$SERVICE_IP | grep "Pod"; sleep 1; done

Self-healing Exercise:

bash

# Delete a pod and watch it recreate
kubectl delete pod pokemon-checker-xyz
kubectl get pods -w

Rolling Update Exercise:

bash

# Update the image and watch rolling update
kubectl set image deployment/pokemon-checker pokemon-checker=new-image:tag
kubectl rollout status deployment/pokemon-checker

License

MIT License - See LICENSE file for details.

Acknowledgments

PokeAPI for providing Pokemon data
Kubernetes community for excellent documentation
Go community for the programming language and tools