Java

Introduction

We have clients using the SpringBoot framework for apps on OpenShift. We also suggest looking at the Quarkus framework as it has a container first priority.

Getting Started

1. First create a new GitLab project using the instance template from the AppBase for your language.

   • The AppBase will provide you with a pattern to deploy applications
   • Will automatically setup GitLab CI/CD tools such as security settings
   • The quickest way to get up and running with OpenShift.
   • Read the README.md file in the repository for latest instructions and notes for your framework.

2. Change into the cloned folder and generate a new Spring Boot application

3. We recommend using the Spring Boot CLI or the Spring Start.

   A basic starting point (recommended):

   spring init -x --build=maven --force -d=web,actuator -n=projectx

   A detailed example specifying more packages, spring version and java version would be:

   spring init -x --build=maven --force -b=2.7.8-SNAPSHOT -j=1.11 -d=web,actuator,security,cloud-eureka,amqp,lombok,flyway,mysql,jdbc,jpa,cloud-loadbalancer,thymeleaf -n=projectx

4. Modify the Dockerfile in the repository as needed:

   • The source folder (see line 9, line 31)
   • The JDK version (see line 2, line 15)

5. Git add all the changes, commit and push to your repository.

   git add .
   git commit -m "first change"
   git push

6. Setup the GitLab CI/CD variables as defined in the README.md in the repository.

TODO

1. OpenShift deployment
2. Gitops

Notes

JAVA_OPTS

Running in a container can cause issues with the heap size and CPU detection if limits are used. We recommend the following environment variable to be set:

    JAVA_OPTS: '-XX:ActiveProcessorCount=2 -XX:+UseParallelGC -XX:MaxRAMPercentage=80'

For more information please read Microsoft's JAVA Containerization recommendations and RedHat's OpenJDK changes.

Actuators

Actuators provide a way to check the health of the application. They should be used for production and zero downtime deployments.