Setting up a development environment for Java apps on Kubernetes

02 Oct 2023

kubernetes

Kubernetes is a popular container orchestration platform that allows you to deploy and manage applications at scale. If you are a Java developer and want to develop and test your applications in a Kubernetes environment, setting up a local development environment can be really helpful. In this blog post, we will walk through the steps to set up a development environment for Java apps on Kubernetes.

Prerequisites

Before you begin, make sure you have the following prerequisites installed on your machine:

Docker: to build and run containers locally
Kubernetes: to create and manage a local Kubernetes cluster
Java Development Kit (JDK): to compile and run Java applications
Maven: to build and manage dependencies for Java projects

Step 1: Set up a Kubernetes cluster

You can use a local Kubernetes cluster such as Minikube or Docker Desktop with Kubernetes enabled. Install the chosen cluster tool and start the cluster.

$ minikube start

Step 2: Create a Docker image for your Java app

To run your Java application on Kubernetes, you need to package it into a Docker image. Create a Dockerfile in your project directory with the following content:

FROM openjdk:11-jdk
COPY . /app
WORKDIR /app
RUN mvn clean package
CMD ["java", "-jar", "target/myapp.jar"]

Build the Docker image using the following command:

$ docker build -t myapp:latest .

Step 3: Deploy Java app to Kubernetes

To deploy your Java app to Kubernetes, you need to write a Kubernetes manifest file (e.g., deployment.yaml) that describes the desired state of your application. Here is an example:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp-container
          image: myapp:latest
          ports:
            - containerPort: 8080

Apply the deployment manifest to your Kubernetes cluster using the following command:

$ kubectl apply -f deployment.yaml

Step 4: Access your Java app

Now that your Java app is deployed on Kubernetes, you can access it using a service. Create a service manifest file (e.g., service.yaml) with the following content:

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

Apply the service manifest to your Kubernetes cluster using the following command:

$ kubectl apply -f service.yaml

You can access your Java app by visiting the external IP address of the LoadBalancer service.

Conclusion

Setting up a development environment for Java apps on Kubernetes can help you test and validate your applications in a Kubernetes-like environment. By following the steps outlined in this blog post, you’ll be able to run and access your Java app on a local Kubernetes cluster.

#java #kubernetes