Spring Boot application template

Purpose

The purpose of this template is to speed up the creation of new Spring applications within HMCTS and help keep the same standards across multiple teams. If you need to create a new app, you can simply use this one as a starting point and build on top of it.

What's inside

The template is a working application with a minimal setup. It contains:

• application skeleton
• setup script to prepare project
• common plugins and libraries
• docker setup
• swagger configuration for api documentation (see how to publish your api documentation to shared repository)
• code quality tools already set up
• integration with Travis CI
• Hystrix circuit breaker enabled
• MIT license and contribution information
• Helm chart using chart-java.

The application exposes health endpoint (http://localhost:4550/health) and metrics endpoint (http://localhost:4550/metrics).

Plugins

The template contains the following plugins:

• checkstyle

  https://docs.gradle.org/current/userguide/checkstyle_plugin.html

  Performs code style checks on Java source files using Checkstyle and generates reports from these checks. The checks are included in gradle's check task (you can run them by executing ./gradlew check command).

• pmd

  https://docs.gradle.org/current/userguide/pmd_plugin.html

  Performs static code analysis to finds common programming flaws. Included in gradle check task.

• jacoco

  https://docs.gradle.org/current/userguide/jacoco_plugin.html

  Provides code coverage metrics for Java code via integration with JaCoCo. You can create the report by running the following command:

    ./gradlew jacocoTestReport
  

  The report will be created in build/reports subdirectory in your project directory.

• io.spring.dependency-management

  https://github.com/spring-gradle-plugins/dependency-management-plugin

  Provides Maven-like dependency management. Allows you to declare dependency management using dependency 'groupId:artifactId:version' or dependency group:'group', name:'name', version:version'.

• org.springframework.boot

  http://projects.spring.io/spring-boot/

  Reduces the amount of work needed to create a Spring application

• org.owasp.dependencycheck

  https://jeremylong.github.io/DependencyCheck/dependency-check-gradle/index.html

  Provides monitoring of the project's dependent libraries and creating a report of known vulnerable components that are included in the build. To run it execute gradle dependencyCheck command.

• com.github.ben-manes.versions

  https://github.com/ben-manes/gradle-versions-plugin

  Provides a task to determine which dependencies have updates. Usage:

    ./gradlew dependencyUpdates -Drevision=release
  

Setup

Located in ./bin/init.sh. Simply run and follow the explanation how to execute it.

Notes

Since Spring Boot 2.1 bean overriding is disabled. If you want to enable it you will need to set spring.main.allow-bean-definition-overriding to true.

JUnit 5 is now enabled by default in the project. Please refrain from using JUnit4 and use the next generation

Building and deploying the application

Building the application

The project uses Gradle as a build tool. It already contains ./gradlew wrapper script, so there's no need to install gradle.

To build the project execute the following command:

  ./gradlew build

Running the application

Create the image of the application by executing the following command:

  ./gradlew assemble

Create docker image:

  docker-compose build

Run the distribution (created in build/install/spring-boot-template directory) by executing the following command:

  docker-compose up

This will start the API container exposing the application's port (set to 4550 in this template app).

In order to test if the application is up, you can call its health endpoint:

  curl http://localhost:4550/health

You should get a response similar to this:

  {"status":"UP","diskSpace":{"status":"UP","total":249644974080,"free":137188298752,"threshold":10485760}}

Alternative script to run application

To skip all the setting up and building, just execute the following command:

./bin/run-in-docker.sh

For more information:

./bin/run-in-docker.sh -h

Script includes bare minimum environment variables necessary to start api instance. Whenever any variable is changed or any other script regarding docker image/container build, the suggested way to ensure all is cleaned up properly is by this command:

docker-compose rm

It clears stopped containers correctly. Might consider removing clutter of images too, especially the ones fiddled with:

docker images

docker image rm <image-id>

There is no need to remove postgres and java or similar core images.

Other

Hystrix offers much more than Circuit Breaker pattern implementation or command monitoring. Here are some other functionalities it provides:

• Separate, per-dependency thread pools
• Semaphores, which you can use to limit the number of concurrent calls to any given dependency
• Request caching, allowing different code paths to execute Hystrix Commands without worrying about duplicating work

License

This project is licensed under the MIT License - see the LICENSE file for details