4. Tooling Images

GitLab Runner can use Docker to run jobs on user provided images. This is possible with the use of Docker executor. The image keyword is the name of the Docker image the Docker executor uses to run CI/CD jobs. You can specify different images for different jobs. For example, choose an Image which contains a Java Development Kit (JDK) for building Java Applications or an Image which contains the .NET SDK for building C# apps. In this Lab section we will show you how to choose and use the right Container Image.

Task 4.1: Choosing tooling images

To build an application or to deploy it, specific languages, frameworks or tools are needed.

Therefore, we need to find the right Container Image.

Good sources for Container Images are trusted registries like Red Hat . You can also use official Images from the software company developing the needed tool.

For tools and languages it is a good starting point to check the Pre-Built CircleCI Docker Images .

Task 4.2: Build the application

The example source is a Java 17 application. For that we use the openjdk-17 Image from Red Hat.

Create a new job inside .gitlab-ci.yml with the following configuration:

• job name: build_application
• stage: build
• image: registry.access.redhat.com/ubi9/openjdk-17:latest
• script:./gradlew assemble

Don’t forget to add the build stage to the stages list.

Task 4.3: Check the pipeline

The pipeline should now look like this:

stages:
  - info
  - build

info:
  stage: info
  script:
    - echo "This is your first stage (ツ)"

build_application:
  stage: build
  tags:
    - build
    - mobiliar
  image: registry.access.redhat.com/ubi9/openjdk-17:latest
  script:
    - ./gradlew assemble

After committing the changes a new pipeline starts using the updated configuration.

Go to your GitLab project and check the pipelines under Build –> Pipelines.

The Java application is built using the Gradle Build Tool

Check the Gradle build log and verify whether the build succeeded or not.

Starting a Gradle Daemon (subsequent builds will be faster)
> Task :compileJava
> Task :processResources
> Task :classes
> Task :resolveMainClassName
> Task :bootJar
> Task :jar
> Task :assemble
BUILD SUCCESSFUL in 39s
5 actionable tasks: 5 executed
Cleaning up file based variables
00:00
Job succeeded