Creating Jenkins Pipeline

• On Dashboard click on New Item. Enter the item name, example myapp, and select Pipeline Option.

• Scroll down to Pipeline and add below Pipeline script under script section. Make sure you replace your-credential-id (obtained in step 8-2), http://link:port (obtained in step 7) and the paths with your actual values. Then click on Save.

This Jenkins pipeline script automates the deployment of a Java application to a Kubernetes cluster. It comprises three stages: Build compiles the Java code, Dockerize builds a Docker image, and Deploy to Minikube applies the Kubernetes deployment using a specified service account token and server URL with TLS verification skipped. The script integrates with Jenkins credentials to securely access the Kubernetes service account token and executes commands to deploy the application to the specified Minikube cluster.

pipeline {
    agent any
    
    stages {
        stage('Build') {
            steps {
                // Compile Java code
                bat "javac \"C:\\Users\\deployJavaAppMain.java\""
            }
        }
        
        stage('Dockerize') {
            steps {
                script {
                    // Disable BuildKit
                    bat 'SET DOCKER_BUILDKIT=0'
                    
                    // Build Docker image
                    bat 'docker build -t java-app "C:\\Users\\deployJavaApp"'
                }
            }
        }
        
        stage('Deploy to Minikube') {
            steps {
                // Apply Kubernetes deployment using the Kubernetes service account
                withCredentials([string(credentialsId: 'your-credential-id', variable: 'KUBE_SA_TOKEN')]) {
                    bat """
                        kubectl apply -f "C:\\Users\\deployJavaApp\\kubernetes-deployment.yaml" \
                        --token="$KUBE_SA_TOKEN" \
                        --server=http://link:port \
                        --insecure-skip-tls-verify
                    """
                }
            }
        }
    }
}

• Then click on Build Now which starts the pipeline to Build and automates the deployment process.

• Now deployment is successful and you can access the deployed application through exposed service or by accessing the pods directly or you can visit the Kubernetes dashboard to manage your deployment.

In modern software development, deploying applications to Kubernetes clusters has become a common practice due to their scalability and reliability. Automating this deployment process using continuous integration and continuous deployment (CI/CD) pipelines with Jenkins streamlines the development workflow and ensures consistent, reliable deployments. This article demonstrates deploying a sample Java application on a Kubernetes cluster using Minikube.