How to Deploy Spring Boot Application in Kubernetes?

Deploying a Spring Boot application in Kubernetes can be a powerful and efficient way to manage and scale your Java-based applications. Kubernetes, an open-source container orchestration platform, simplifies the deployment, scaling, and management of containerized applications. In this guide, we will walk through the steps to deploy a Spring Boot application in Kubernetes, ensuring a smooth and seamless deployment process.

Setting Up Your Environment:

Before diving into the deployment process, make sure you have the following prerequisites:

1. Docker: Ensure that Docker is installed on your local machine. You can download and install Docker from the official website (https://www.docker.com/).

2. Kubernetes: Install Kubernetes on your local machine or use a cloud-based Kubernetes service like Google Kubernetes Engine (GKE), Azure Kubernetes Service (AKS), or Amazon EKS.

Containerizing the Spring Boot Application:

The first step is to containerize your Spring Boot application using Docker. Create a Dockerfile in the root of your project with the following content:

# Use an official OpenJDK runtime as a parent image
FROM openjdk:11-jre-slim

# Set the working directory to /app
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . /app

# Specify the command to run on container start
CMD ["java", "-jar", "your-spring-boot-app.jar"]

Replace "your-spring-boot-app.jar" with the actual name of your Spring Boot application JAR file.

Building and Pushing Docker Image:

Build the Docker image using the following command:

docker build -t your-docker-username/your-spring-boot-app:latest .

Push the image to Docker Hub or any other container registry:

docker push your-docker-username/your-spring-boot-app:latest

Deploying to Kubernetes:

Now, let's deploy the Spring Boot application to Kubernetes.

Step 1: Create Kubernetes Deployment:

Create a file named deployment.yaml with the following content:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: your-spring-boot-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: your-spring-boot-app
  template:
    metadata:
      labels:
        app: your-spring-boot-app
    spec:
      containers:
        - name: your-spring-boot-app
          image: your-docker-username/your-spring-boot-app:latest
          ports:
            - containerPort: 8080

Step 2: Apply the Deployment:

Apply the deployment to your Kubernetes cluster:

kubectl apply -f deployment.yaml

Step 3: Expose the Service:

Create a file named service.yaml with the following content:

apiVersion: v1
kind: Service
metadata:
  name: your-spring-boot-app-service
spec:
  selector:
    app: your-spring-boot-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
  type: LoadBalancer

Apply the service to your Kubernetes cluster:

kubectl apply -f service.yaml

Accessing the Spring Boot Application:

After a successful deployment, get the external IP of the service:

kubectl get services your-spring-boot-app-service

Access your Spring Boot application using the provided external IP.

Congratulations! You have successfully deployed a Spring Boot application in Kubernetes. This scalable and efficient deployment approach ensures that your application is running smoothly in a containerized environment. Kubernetes provides the flexibility and tools necessary to manage your application's lifecycle effortlessly.