Deploying a Java Application on VPS: Advanced Level with CI/CD

Deploying a Java Application on VPS: Advanced Level with CI/CD, Docker and SSL

In this article, we will look at the advanced process of deploying a Java application on a VPS (Virtual Private Server). We will not dwell on basic steps like installing JDK or running a JAR file. Instead, we will focus on setting up a CI/CD pipeline, containerization with Docker, using Nginx as a reverse proxy, automatically obtaining SSL certificates, as well as monitoring and fault tolerance of the application.

It is assumed that you already have a VPS with Ubuntu 22.04 LTS, a base domain, and are familiar with the Linux command line. All code examples are written in Java 17+ using Spring Boot, but the principles apply to any Java framework.

1. Containerizing a Java Application with Docker

The first step towards advanced deployment is packaging the application into a Docker container. This ensures environment reproducibility and simplifies deployment.

Create a Dockerfile in the project root:

# Use multi-stage build to reduce the size of the final imageFROM maven:3.9.6-eclipse-temurin-17 AS builderWORKDIR /appCOPY pom.xml .RUN mvn dependency:go-offlineCOPY src ./srcRUN mvn clean package -DskipTests

FROM eclipse-temurin:17-jre-alpineWORKDIR /appCOPY --from=builder /app/target/*.jar app.jarEXPOSE 8080ENTRYPOINT ["java", "-jar", "app.jar"]

docker-compose.yml file for running with a database:

version: '3.8'services:  app:    build: .    ports:      - "8080:8080"    environment:      - SPRING_DATASOURCE_URL=jdbc:postgresql://db:5432/mydb      - SPRING_DATASOURCE_USERNAME=user      - SPRING_DATASOURCE_PASSWORD=pass    depends_on:      - db    restart: unless-stopped

  db:    image: postgres:15-alpine    environment:      POSTGRES_DB: mydb      POSTGRES_USER: user      POSTGRES_PASSWORD: pass    volumes:      - pgdata:/var/lib/postgresql/data    restart: unless-stopped

volumes:  pgdata:

After building the image with the command docker compose build, you will have a container ready for deployment.

2. Setting up a CI/CD Pipeline (GitHub Actions)

Deployment automation is a key element of the advanced level. We use GitHub Actions to build, test, and send the image to the server.

Create the file .github/workflows/deploy.yml:

name: Deploy Java App to VPS

on:  push:    branches: [ main ]

jobs:  build-and-deploy:    runs-on: ubuntu-latest    steps:      - uses: actions/checkout@v4

      - name: Set up JDK 17        uses: actions/setup-java@v4        with:          java-version: '17'          distribution: 'temurin'

      - name: Build with Maven        run: mvn clean package

      - name: Build Docker image        run: docker build -t myapp:latest .

      - name: Save Docker image to tar        run: docker save myapp:latest | gzip > myapp.tar.gz

      - name: Copy image to VPS via SCP        uses: appleboy/scp-action@v0.1.7        with:          host: ${{ secrets.VPS_HOST }}          username: ${{ secrets.VPS_USER }}          key: ${{ secrets.VPS_SSH_KEY }}          source: "myapp.tar.gz"          target: "/opt/app/"

      - name: Deploy on VPS        uses: appleboy/ssh-action@v1.0.3        with:          host: ${{ secrets.VPS_HOST }}          username: ${{ secrets.VPS_USER }}          key: ${{ secrets.VPS_SSH_KEY }}          script: |            cd /opt/app            docker load < myapp.tar.gz            docker compose down            docker compose up -d            rm myapp.tar.gz

Don't forget to add the secrets VPS_HOST, VPS_USER, VPS_SSH_KEY in the settings