Java Spring Continuous Integration#

This guide shows you how to use Semaphore to set up a continuous integration (CI) pipeline for a Java Spring application.

Demo project#

Semaphore maintains an example Java Spring project:

In the repository you will find an annotated Semaphore configuration file .semaphore/semaphore.yml.

The application uses Spring Boot, Maven, JUnit for unit and integration tests, JMeter for performance testing, and Docker for deployment.

Overview of the CI/CD pipeline#

The Semaphore pipeline performs the following tasks:

  1. Build the project
  2. Run unit and integration tests in parallel
  3. Run performance tests
  4. Build Docker image
  5. Push image to a container registry

Java Spring CI/CD pipeline

Sample configuration#

The entry pipeline performs build and test steps:

# .semaphore/semaphore.yml
# Use the latest stable version of Semaphore 2.0 YML syntax:
version: v1.0

# Name of your pipeline. In this example we connect two pipelines with
# a promotion, so it helps to differentiate what's the job of each.
name: Java Spring example CI pipeline on Semaphore

# An agent defines the environment in which your code runs.
# It is a combination of one of available machine types and operating
# system images. See:
# https://docs.semaphoreci.com/article/20-machine-types
# https://docs.semaphoreci.com/article/32-ubuntu-1804-image
agent:
  machine:
    type: e1-standard-2
    os_image: ubuntu1804

# Blocks are the heart of a pipeline and are executed sequentially.
# Each block has a task that defines one or more jobs. Jobs define the
# commands to execute.
# See https://docs.semaphoreci.com/article/62-concepts
blocks:

  - name: "Build"
    task:
      # Set environment variables that your project requires.
      # See https://docs.semaphoreci.com/article/66-environment-variables-and-secrets
      env_vars:
        - name: MAVEN_OPTS
          value: "-Dmaven.repo.local=.m2"

      jobs:
      - name: Build
        commands:
          # Checkout code from Git repository. This step is mandatory if the
          # job is to work with your code.
          - checkout

            # Restore dependencies from cache, command won't fail if it's
            # missing.
            # More on caching: https://docs.semaphoreci.com/article/149-caching
          - cache restore

          - mvn -q package jmeter:configure -Dmaven.test.skip=true

            # Store the latest version of dependencies in cache,
            # to be used in next blocks and future workflows:
          - cache store

  - name: "Test"
    task:
      env_vars:
        - name: MAVEN_OPTS
          value: "-Dmaven.repo.local=.m2"

      # This block runs two jobs in parallel and they both share common
      # setup steps. We can group them in a prologue.
      # See https://docs.semaphoreci.com/article/50-pipeline-yaml#prologue
      prologue:
        commands:
          - checkout
          - cache restore
          - mvn -q test-compile -Dmaven.test.skip=true
      jobs:
      - name: Unit tests
        commands:
          - mvn test
      - name: Integration tests
        commands:
          - mvn test -Pintegration-testing

  - name: "Performance tests"
    task:
      env_vars:
        - name: MAVEN_OPTS
          value: "-Dmaven.repo.local=.m2"
      prologue:
        commands:
          - checkout
          - cache restore
      jobs:
      - name: Benchmark
        commands:
          - java -version
          # Run application in detached mode:
          - java -jar target/spring-pipeline-demo.jar > /dev/null &
          # Wait for the spring boot application to boot
          - sleep 20
          - mvn -q jmeter:jmeter
          - mvn jmeter:results


# If all tests pass, we move on to build a Docker image.
# This is a job for a separate pipeline which we link with a promotion.
#
# What happens outside semaphore.yml will not appear in GitHub pull
# request status report.
#
# In this example we run docker build automatically on every branch.
# You may want to limit it by branch name, or trigger it manually.
# For more on such options, see:
# https://docs.semaphoreci.com/article/50-pipeline-yaml#promotions
promotions:
  - name: Dockerize
    pipeline_file: docker-build.yml
    auto_promote_on:
      - result: passed

The pipeline ends with a promotion which is triggered automatically if all blocks finished successfully.

Authenticate with a Docker registry#

The Docker build pipeline produces a container image and pushes it to a Docker registry. In this case, the registry is Docker Hub, but you can use any other. For pipeline to work, you need to authenticate.

Add your container registry credentials to ./docker-hub-secret.yml, which is provided in the repository as a template. The credentials should remain private, so don't publish them to your Git repository by mistake.

Create a secret on Semaphore so that you can safely export DOCKER_USERNAME and DOCKER_PASSWORD environment variables in your pipeline:

sem create -f docker-hub-secret.yml

The Docker build pipeline#

# .semaphore/docker-build.yml
version: v1.0
name: Docker build
agent:
  machine:
    # Use a machine type with more RAM and CPU power for faster container
    # builds:
    type: e1-standard-4
    os_image: ubuntu1804

blocks:
  - name: "Build"
    task:
      env_vars:
        - name: MAVEN_OPTS
          value: "-Dmaven.repo.local=.m2"
        - name: ENVIRONMENT
          value: "dev"

      # Mount a secret which defines DOCKER_USERNAME and DOCKER_PASSWORD
      # environment variables.
      # For info on creating secrets, see:
      # https://docs.semaphoreci.com/article/66-environment-variables-and-secrets
      secrets:
      - name: docker-hub

      prologue:
        commands:
          - checkout
          - cache restore

      jobs:
      - name: Build and deploy docker container
        commands:
          - mvn -q package -Dmaven.test.skip=true

          # Authenticate with Docker Hub
          # using environment variables docker-hub secret:
          - echo $DOCKER_PASSWORD | docker login  --username "$DOCKER_USERNAME" --password-stdin

          # Use docker layer caching and reuse unchanged layers to build a new
          # container image faster.
          # To do that, we first need to pull a previous version of container:
          - docker pull semaphoredemos/semaphore-demo-java-spring:latest || true


          # Build a new image based on pulled image, if present.
          # You could use $SEMAPHORE_WORKFLOW_ID environment variable to
          # produce a unique image tag.  For a list of available environment
          # variables on Semaphore, see:
          # https://docs.semaphoreci.com/article/12-environment-variables
          - docker build --cache-from semaphoredemos/semaphore-demo-java-spring:latest --build-arg ENVIRONMENT="${ENVIRONMENT}" -t semaphoredemos/semaphore-demo-java-spring:latest .

          # Push a new image to container registry:
          - docker push semaphoredemos/semaphore-demo-java-spring:latest

Run the demo project yourself#

A good way to start using Semaphore is to take a demo project and run it yourself. Here’s how to build the demo project with your own account:

  1. Fork the project on GitHub to your own account.
  2. Clone the repository on your local machine.
  3. In Semaphore, follow the link in the sidebar to create a new project.
  4. Create your secret as per instructions above.
  5. Edit any file and push GitHub, and Semaphore will run the CI/CD pipeline.