In the modern landscape of software engineering, Continuous Integration and Continuous Deployment (CI/CD) are no longer optional luxuries; they are the circulatory system of any healthy development lifecycle. For Java developers in 2025, the challenge isn’t just setting up a pipeline—it’s choosing the right tool and configuring it for maximum efficiency, security, and maintainability.
Whether you are migrating a legacy monolith to microservices or spinning up a new Spring Boot 3 application, the pipeline defines your velocity.
In this deep-dive guide, we will explore the three titans of the industry: Jenkins, GitHub Actions, and GitLab CI. We will move beyond high-level theory and implement a complete, production-ready pipeline for a Java 21 project on each platform.
Prerequisites and Environment #
Before we dive into the configurations, let’s establish our baseline environment. We assume you are working with a standard modern Java stack:
- Java Development Kit: JDK 21 (LTS).
- Build Tool: Maven 3.9+ (Gradle users can easily adapt the commands).
- Framework: Spring Boot 3.x.
- Containerization: Docker.
- Version Control: Git.
The Target Pipeline Architecture #
Regardless of the tool we choose, a robust Java pipeline should generally follow these stages:
- Checkout: Retrieve code from the repository.
- Dependency Resolution: Download Maven dependencies (with caching).
- Compile & Test: Run unit tests and static analysis.
- Build: Package the application (JAR).
- Containerize: Build a Docker image.
- Deploy: Push to a registry or deploy to a staging environment.
Here is a visual representation of the workflow we will implement:
1. The Enterprise Veteran: Jenkins #
Jenkins remains the undisputed king of flexibility and enterprise adoption, despite the rise of newer tools. In 2025, we strictly use Declarative Pipelines (Jenkinsfile) rather than the old UI-based configuration.
Setup and Configuration #
To run this, you need a Jenkins controller and an agent with Docker installed. We will use the Docker Pipeline plugin to ensure a clean build environment.
The Jenkinsfile
#
Place this file in the root of your project.
pipeline {
agent any
environment {
// Global variables
JAVA_VERSION = '21'
DOCKER_IMAGE = 'my-org/my-java-app'
REGISTRY_CREDENTIALS_ID = 'docker-hub-creds'
}
tools {
// Assumes 'maven-3.9' is configured in Jenkins Global Tool Configuration
maven 'maven-3.9'
// Assumes 'jdk-21' is configured
jdk 'jdk-21'
}
stages {
stage('Checkout') {
steps {
checkout scm
}
}
stage('Build & Test') {
steps {
script {
// Using verify to run unit tests and package
sh 'mvn clean verify'
}
}
post {
always {
junit 'target/surefire-reports/*.xml'
}
}
}
stage('Static Analysis') {
steps {
// Example: SpotBugs or Checkstyle
sh 'mvn checkstyle:check'
}
}
stage('Build Docker Image') {
steps {
script {
dockerImage = docker.build("${DOCKER_IMAGE}:${env.BUILD_NUMBER}")
}
}
}
stage('Push Image') {
steps {
script {
docker.withRegistry('', REGISTRY_CREDENTIALS_ID) {
dockerImage.push()
dockerImage.push('latest')
}
}
}
}
}
post {
failure {
mail to: '[email protected]',
subject: "Failed Pipeline: ${currentBuild.fullDisplayName}",
body: "Something went wrong. Check logs: ${env.BUILD_URL}"
}
success {
echo 'Pipeline completed successfully!'
}
}
}Jenkins Pros & Cons #
- Pros: unparalleled plugin ecosystem, supports complex logic, works great in air-gapped environments.
- Cons: High maintenance (needs hosting), steep learning curve for Groovy syntax.
2. The Cloud Native: GitHub Actions #
GitHub Actions (GHA) has exploded in popularity due to its seamless integration with where code lives. It uses YAML and a marketplace of “Actions” to compose workflows.
The Workflow File #
Create .github/workflows/maven-pipeline.yml.
name: Java CI/CD Pipeline
on:
push:
branches: [ "main" ]
pull_request:
branches: [ "main" ]
jobs:
build-and-deploy:
runs-on: ubuntu-latest
steps:
- name: Checkout Code
uses: actions/checkout@v4
- name: Set up JDK 21
uses: actions/setup-java@v4
with:
java-version: '21'
distribution: 'temurin'
cache: 'maven' # Automatic dependency caching
- name: Build with Maven
run: mvn -B package --file pom.xml
- name: Run Tests
run: mvn test
- name: Login to Docker Hub
if: github.event_name != 'pull_request' # Don't push on PRs
uses: docker/login-action@v3
with:
username: ${{ secrets.DOCKERHUB_USERNAME }}
password: ${{ secrets.DOCKERHUB_TOKEN }}
- name: Set up Docker Buildx
if: github.event_name != 'pull_request'
uses: docker/setup-buildx-action@v3
- name: Build and Push Docker Image
if: github.event_name != 'pull_request'
uses: docker/build-push-action@v5
with:
context: .
push: true
tags: |
my-org/my-java-app:${{ github.sha }}
my-org/my-java-app:latestKey Feature: setup-java Caching
#
Notice the cache: 'maven' line. GitHub Actions simplifies dependency caching significantly compared to Jenkins. It automatically hashes your pom.xml and restores the ~/.m2 directory, drastically reducing build times for large Spring Boot projects.
3. The Integrated DevOps Platform: GitLab CI #
GitLab CI is loved for its “configuration as code” philosophy and tight integration with the GitLab repository. It relies on a .gitlab-ci.yml file and the concept of “Runners”.
The Configuration #
Create .gitlab-ci.yml in the project root.
stages:
- build
- test
- package
- deploy
variables:
MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository"
DOCKER_IMAGE_NAME: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA
# Cache Maven dependencies between jobs
cache:
paths:
- .m2/repository
image: maven:3.9.6-eclipse-temurin-21
build_job:
stage: build
script:
- mvn compile
test_job:
stage: test
script:
- mvn test
artifacts:
reports:
junit: target/surefire-reports/*.xml
package_job:
stage: package
script:
- mvn package -DskipTests
artifacts:
paths:
- target/*.jar
expire_in: 1 hour
docker_build:
stage: deploy
image: docker:24.0.5
services:
- docker:24.0.5-dind
before_script:
- docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
script:
- docker build -t $DOCKER_IMAGE_NAME .
- docker push $DOCKER_IMAGE_NAME
only:
- mainGitLab CI Architecture #
GitLab uses a Docker-in-Docker (dind) approach often, or allows you to specify a Docker image for each job. The artifacts feature is crucial here; unlike GitHub Actions where steps run in the same runner context, GitLab jobs are isolated. We must pass the compiled JAR from package_job to docker_build using artifacts.
Comparison: Choosing the Right Tool for 2025 #
Choosing between these three depends heavily on your team’s existing infrastructure and goals. Here is a breakdown of how they stack up against each other.
| Feature | Jenkins | GitHub Actions | GitLab CI |
|---|---|---|---|
| Hosting | Self-hosted (Requires Maintenance) | SaaS (Free for public) / Self-hosted Runners | SaaS / Self-hosted |
| Configuration | Groovy (Jenkinsfile) |
YAML | YAML |
| Learning Curve | Steep | Low to Medium | Medium |
| Ecosystem | Massive Plugin Library | Extensive Marketplace | Built-in functionality |
| Docker Support | Good (via plugins) | Excellent (Native) | Excellent (Native Container Registry) |
| Java Caching | Manual Config Required | Native (setup-java) |
Manual Config Required |
| Best For | Complex, custom enterprise flows | Open Source, GitHub-centric teams | Integrated DevOps teams |
Performance Optimization & Best Practices #
Regardless of the platform, follow these Java-specific best practices to keep your pipeline green and fast.
1. Maven Dependency Caching #
Downloading the internet (Maven Central) on every build is a performance killer.
- GitHub: Use
actions/setup-javawithcache: 'maven'. - GitLab/Jenkins: Configure a persistent volume or use built-in caching keys based on the checksum of
pom.xml.
2. Multi-Stage Docker Builds #
Don’t copy your source code into the final production image. Build the JAR in the CI pipeline (or a build stage) and copy only the JAR to a distroless runtime image.
Example Dockerfile:
# Stage 1: Build is done in CI, or use a build stage here
# For CI pipelines, we usually just copy the JAR built in previous steps
FROM eclipse-temurin:21-jre-alpine
WORKDIR /app
COPY target/*.jar app.jar
ENTRYPOINT ["java", "-jar", "app.jar"]Note: Using Alpine Linux with Java 21 significantly reduces the image footprint.
3. Fail Fast #
Run your fastest checks first.
- Checkstyle / Spotless (Seconds)
- Unit Tests (Minutes)
- Integration Tests (Minutes to Hours)
If formatting fails, there is no need to spin up a Docker container for integration tests.
4. Security Scanning #
In 2025, DevSecOps is standard. Embed tools like OWASP Dependency-Check or Snyk into your Maven build to detect vulnerabilities in third-party libraries before deployment.
<!-- Add to pom.xml build plugins -->
<plugin>
<groupId>org.owasp</groupId>
<artifactId>dependency-check-maven</artifactId>
<version>9.0.9</version>
<executions>
<execution>
<goals>
<goal>check</goal>
</goals>
</execution>
</executions>
</plugin>Conclusion #
The “best” CI/CD tool is the one that gets out of your way and lets you ship code confidently.
- Choose Jenkins if you have complex legacy requirements, need complete control over the infrastructure, or have a dedicated DevOps team to manage the controller.
- Choose GitHub Actions if your code is already on GitHub. The developer experience is unmatched, and the setup time is practically zero.
- Choose GitLab CI if you want a unified platform where planning, coding, and deploying happen under one roof.
For a new Java project starting in 2025, GitHub Actions generally offers the best balance of ease of use and power, especially with the simplified Java caching mechanism. However, mastering the Jenkinsfile remains a highly marketable skill in the enterprise world.
Start small: automate the build and unit tests today. Once that is stable, add Docker packaging and deployment steps. Automation is a journey, not a destination.
Further Reading #
Disclaimer: Code examples are provided for educational purposes. Always review security configurations before deploying to production environments.