Kubernetes Made Simple: A Guide for JVM Developers

This repository contains the companion code for the "Kubernetes Made Simple: A Guide for JVM Developers" article, demonstrating how to deploy a Kotlin Spring Boot application to Kubernetes.

About This Project

This project provides a hands-on, practical example of deploying JVM-based microservices on Kubernetes. It showcases a complete workflow from containerization to deployment, covering essential Kubernetes concepts in a way that's approachable for Java and Kotlin developers.

What You'll Find Here

• Containerization with Docker: A production-ready Dockerfile for packaging Kotlin/Spring Boot applications
• Kubernetes Fundamentals: Working examples of Deployments, Services, and Pods
• Configuration Management: Using ConfigMaps for application settings and Secrets for sensitive data
• Database Integration: PostgreSQL deployment on Kubernetes with persistent storage
• Advanced Routing: Ingress configuration with canary deployments for progressive rollouts

Technologies Used

• Kotlin - A modern, expressive JVM language fully interoperable with Java
• Spring Boot - The popular framework for building production-grade applications
• Kubernetes - Container orchestration platform for deploying and managing microservices
• Docker - Containerization platform for packaging applications
• PostgreSQL - Relational database for persistent data storage
• Minikube - Local Kubernetes environment for development and testing

This project demonstrates how Kotlin's concise syntax, null safety, and seamless Spring integration make it an excellent choice for building cloud-native microservices.

Deployment Instructions

1. Build kotlin app

   ./gradlew clean build

2. Build Docker image (builds the app inside container):

   docker build -f Dockerfile -t kotlin-app:latest .

3. Deploy to Kubernetes:

   kubectl apply -f k8s/postgres-secret.yaml
   kubectl apply -f k8s/postgres.yaml
   kubectl apply -f k8s/deployment.yaml
   kubectl apply -f k8s/service.yaml

4. Check deployment status:

   kubectl get pods
   kubectl get services

5. Test the application:

   minikube service kotlin-app-service

Cleanup

kubectl delete -f k8s/

Other Versions

This is the finished version of the tutorial. You can view other versions by navigating to different branches:

• starter branch
• config-maps branch
• ingress branch