Step-by-Step: Deploy Spring Boot on Kubernetes

 1. Build the Spring Boot App

a)Make sure your app is working locally, then build or run it using Maven or Gradle:

./mvnw clean package

b)If you want to skip tests while building

./mvnw clean package -DskipTests

This creates a target/<my-spring-boot-app-0.0.1-SNAPSHOT>.jar file.

(Replace my-spring-boot-app with your actual artifact ID)

c)Then run the JAR Locally

java -jar target/my-spring-boot-app-0.0.1-SNAPSHOT.jar

d) 📁 Example Directory After Build:
my-spring-boot-app/

│

├── src/

├── target/

│   ├── classes/

│   ├── my-spring-boot-app-0.0.1-SNAPSHOT.jar

│   └── ...

├── pom.xml

├── mvnw

├── mvnw.cmd

└── ...

2. Create a Dockerfile

In your project root, create a file named Dockerfile:

FROM openjdk:17

ARG JAR_FILE=target/*.jar

COPY ${JAR_FILE} app.jar

ENTRYPOINT ["java", "-jar", "/app.jar"]

3. Build and Push the Docker Image

docker build -t your-dockerhub-username/springboot-app:latest

Push it to Docker Hub (or any container registry):

docker push your-dockerhub-username/springboot-app:latest

Note: Replace your-dockerhub-username accordingly.

4. Create Kubernetes Deployment YAML

Create a file named deployment.yaml:

apiVersion: apps/v1

kind: Deployment

metadata:

  name: springboot-deployment

spec:

  replicas: 2

  selector:

    matchLabels:

      app: springboot-app

  template:

    metadata:

      labels:

        app: springboot-app

    spec:

      containers:

      - name: springboot-container

        image: your-dockerhub-username/springboot-app:latest

        ports:

        - containerPort: 8080

5. Create Kubernetes Service YAML

Create a file named service.yaml:

apiVersion: v1

kind: Service

metadata:

  name: springboot-service

spec:

  selector:

    app: springboot-app

  ports:

    - protocol: TCP

      port: 80

      targetPort: 8080

  type: LoadBalancer  # Use NodePort if not using a cloud provider

6. Deploy to Kubernetes

Apply the configuration:

kubectl apply -f deployment.yaml

kubectl apply -f service.yaml

7. Verify

kubectl get pods

kubectl get deployments

kubectl get services

Look for the EXTERNAL-IP of your service (may take a minute to appear if using LoadBalancer on cloud).

8. Access the App

Open the EXTERNAL-IP in your browser. If using NodePort, access it with:

http://<Node-IP>:<NodePort>

Tips:

Use ConfigMap or Secrets for environment variables

For production, consider using Helm, Ingress, TLS, and Horizontal Pod Autoscaler.

For local Kubernetes: use Minikube, Docker Desktop, or Kind.

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