Build, Test, Dockerize and Deploy Your Spring Boot Application Automatically

Modern software development is all about delivering applications quickly and reliably. Manually building JAR files, creating Docker images, pushing them to Docker Hub, logging into servers, and restarting applications every time you make a code change is time-consuming and error-prone.

This is where Continuous Integration (CI) and Continuous Deployment (CD) come in.

In this guide, you'll learn how to build a complete production-ready CI/CD pipeline for a Spring Boot application using:

• Spring Boot

• Maven

• Docker

• Docker Hub

• GitHub Actions

• AWS EC2

By the end of this tutorial, every time you push code to the main branch, GitHub will automatically:

• Build your Spring Boot project

• Generate a JAR file

• Build a Docker image

• Push the Docker image to Docker Hub

• Connect to your EC2 server

• Pull the latest Docker image

• Stop the old container

• Start the new container

No manual deployment required.

What is CI/CD?

Before writing any code, let's understand the basic concepts.

What is Continuous Integration (CI)?

Continuous Integration is the practice of automatically building and testing your application whenever developers push code.

Instead of manually checking whether your project builds successfully, a CI server does it automatically.

For example:

Developer Pushes Code
        │
        ▼
GitHub
        │
        ▼
GitHub Actions
        │
        ▼
Compile Project
        │
        ▼
Run Tests
        │
        ▼
Generate JAR

Benefits include:

• Detects build failures early

• Prevents broken code from reaching production

• Improves team collaboration

• Ensures code always remains deployable

What is Continuous Deployment (CD)?

Continuous Deployment means automatically deploying your application after the build succeeds.

Instead of manually copying files to the server:

Build Success
      │
      ▼
Create Docker Image
      │
      ▼
Push to Docker Hub
      │
      ▼
Connect to EC2
      │
      ▼
Deploy New Version

Benefits:

• Faster releases

• Zero manual work

• Reduced deployment mistakes

• Consistent deployment process

Architecture of Our CI/CD Pipeline

Developer

      │

git push

      │

GitHub Repository

      │

GitHub Actions Workflow

      │

Build Spring Boot Application

      │

Generate JAR

      │

Build Docker Image

      │

Push Image to Docker Hub

      │

SSH to AWS EC2

      │

Pull Latest Image

      │

Stop Old Container

      │

Run New Container

      │

Application Live

Prerequisites

Before starting, make sure you have:

• Java 21 or Java 17

• Maven

• Docker installed locally

• Git installed

• GitHub account

• Docker Hub account

• AWS EC2 instance

• Spring Boot application

Step 1: Create a Spring Boot Project

You can create a Spring Boot project using Spring Initializr or your preferred IDE.

Verify that the application runs:

mvn spring-boot:run

or

mvn clean package

A successful build generates:

target/

    spring-boot-app.jar

Step 2: Create a Dockerfile

Inside the project root, create a file named:

Dockerfile

Add:

FROM eclipse-temurin:21-jre

WORKDIR /app

COPY target/*.jar app.jar

EXPOSE 8080

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

Explanation

FROM

Specifies the base image.

FROM eclipse-temurin:21-jre

This image already contains Java Runtime Environment.

WORKDIR

Creates the working directory.

WORKDIR /app

COPY

Copies the generated JAR.

COPY target/*.jar app.jar

EXPOSE

Documents the application's port.

EXPOSE 8080

ENTRYPOINT

Starts the Spring Boot application.

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

Step 3: Build Docker Image

Build the application first.

mvn clean package

Build Docker image.

docker build -t spring-boot-app .

Run it.

docker run -d -p 8080:8080 spring-boot-app

Open:

http://localhost:8080

Step 4: Push Image to Docker Hub

Login.

docker login

Tag image.

docker tag spring-boot-app yourusername/spring-boot-app:latest

Push.

docker push yourusername/spring-boot-app:latest

Now the image is stored in Docker Hub.

Step 5: Prepare AWS EC2

Launch an EC2 instance.

Install Docker.

Amazon Linux 2023:

sudo dnf install docker -y

Start Docker.

sudo systemctl start docker

Enable Docker.

sudo systemctl enable docker

Allow Docker without sudo.

sudo usermod -aG docker ec2-user

Reconnect to the server.

Verify.

docker --version

Step 6: Create GitHub Secrets

Go to:

Repository

↓

Settings

↓

Secrets and Variables

↓

Actions

Create:

DOCKER_USERNAME
DOCKER_PASSWORD
EC2_HOST
EC2_USER
EC2_SSH_KEY

These values remain encrypted and are never exposed in your workflow logs.

Step 7: Create GitHub Actions Workflow

Create:

.github/workflows/deploy.yml

Paste:

name: Spring Boot CI/CD

on:
  push:
    branches:
      - main

env:
  IMAGE_NAME: spring-boot-app

jobs:
  build-deploy:

    runs-on: ubuntu-latest

    steps:

      - name: Checkout Source
        uses: actions/checkout@v4

      - name: Setup Java
        uses: actions/setup-java@v4
        with:
          distribution: temurin
          java-version: 21
          cache: maven

      - name: Build Project
        run: mvn clean package -DskipTests

      - name: Login Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Build Docker Image
        run: docker build -t ${{ secrets.DOCKER_USERNAME }}/spring-boot-app:latest .

      - name: Push Image
        run: docker push ${{ secrets.DOCKER_USERNAME }}/spring-boot-app:latest

      - name: Deploy to EC2
        uses: appleboy/[email protected]
        with:
          host: ${{ secrets.EC2_HOST }}
          username: ${{ secrets.EC2_USER }}
          key: ${{ secrets.EC2_SSH_KEY }}
          script: |

            docker pull ${{ secrets.DOCKER_USERNAME }}/spring-boot-app:latest

            docker stop spring-boot-app || true

            docker rm spring-boot-app || true

            docker run -d \
              --name spring-boot-app \
              --restart unless-stopped \
              -p 8080:8080 \
              ${{ secrets.DOCKER_USERNAME }}/spring-boot-app:latest

            docker image prune -f

Understanding Every Step

Trigger

on:
  push:
    branches:
      - main

Whenever code is pushed to the main branch, the workflow starts automatically.

Checkout Repository

uses: actions/checkout@v4

Downloads your repository onto the GitHub Actions runner so subsequent steps can access your source code.

Setup Java

uses: actions/setup-java@v4

Installs Java on the runner. The Maven cache speeds up future builds by reusing downloaded dependencies.

Build Project

mvn clean package -DskipTests

This command:

• Deletes old build files

• Compiles the project

• Packages it into a JAR

• Skips tests for faster deployment (consider running tests in production pipelines)

Login to Docker Hub

Authenticates securely using the credentials stored in GitHub Secrets.

Build Docker Image

Packages your application and runtime into a Docker image.

Push Docker Image

Uploads the image to Docker Hub so it can be pulled from your server.

SSH to EC2

The workflow connects securely to your EC2 instance using your private SSH key.

Pull Latest Image

Downloads the newest image from Docker Hub.

Stop Existing Container

docker stop spring-boot-app || true

Stops the currently running container if it exists. The || true prevents the workflow from failing when the container is not present.

Remove Old Container

docker rm spring-boot-app || true

Removes the stopped container to avoid name conflicts.

Start New Container

docker run -d \
--name spring-boot-app \
--restart unless-stopped \
-p 8080:8080

The options mean:

• -d runs in the background.

• --name assigns a readable container name.

• --restart unless-stopped restarts the container after server reboots.

• -p 8080:8080 maps host port 8080 to the container's port 8080.

Clean Up

docker image prune -f

Removes unused images to free disk space on the server.

Testing the Pipeline

Commit and push your changes:

git add .
git commit -m "Deploy application"
git push origin main

GitHub Actions will execute every step automatically. You can monitor progress under the Actions tab in your GitHub repository.

Common Deployment Issues

Application not accessible

• Verify the Docker port mapping.

• Ensure server.port matches the exposed port.

• Check EC2 Security Group inbound rules.

• Confirm any host firewall allows the port.

• Review container logs with docker logs spring-boot-app.

Docker requires sudo

Add your user to the Docker group:

sudo usermod -aG docker ec2-user

Log out and reconnect to apply the new group membership.

GitHub Actions cannot connect to EC2

• Verify the public IP or DNS.

• Confirm SSH is enabled.

• Ensure port 22 is open in the Security Group.

• Check that the private key stored in EC2_SSH_KEY matches the server.

Docker image not updating

Force a fresh image pull:

docker pull yourusername/spring-boot-app:latest

Using version tags instead of only latest is also a good practice for production deployments.

Best Practices

• Use versioned Docker image tags (for example, v1.0.0) in addition to latest.

• Keep sensitive values in GitHub Secrets.

• Run automated tests before deployment.

• Use HTTPS with a reverse proxy such as Nginx.

• Monitor logs and application health.

• Regularly update your base Docker images and dependencies.

• Consider blue-green or rolling deployments for zero-downtime releases as your application grows.

Conclusion

A well-designed CI/CD pipeline removes repetitive deployment work and makes releases faster, more reliable, and easier to maintain. By combining Spring Boot, Maven, Docker, Docker Hub, GitHub Actions, and AWS EC2, you can automatically build, package, and deploy your application every time you push code to GitHub.

Once you've mastered this workflow, you can extend it with automated testing, security scanning, infrastructure as code, and deployment strategies such as rolling or blue-green deployments to create a production-grade DevOps pipeline.