If the DOCKER_IMAGE CI/CD variable is not specified, what does CI_APPLICATION_REPOSITORY default to?

When the DOCKER_IMAGE CI/CD variable is not specified, the CI_APPLICATION_REPOSITORY defaults to the value of $CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG. This default behavior provides a structured naming convention for Docker images built within the CI/CD process, ensuring that the resulting images are easily identifiable and linked to specific commits and branches.

The $CI_REGISTRY_IMAGE variable typically contains the path to the project’s container registry that is set in the GitLab project settings. This allows for the images to be stored in the correct registry associated with the project. Meanwhile, $CI_COMMIT_REF_SLUG generates a URL-friendly version of the branch or tag name, which helps in organizing images according to their associated source code version.

By combining these two variables, the system creates a clear, standardized format for the image repository that reflects both the project’s registration in the container registry and the precise context of the code version being built, which aids in traceability and organization of docker images in the CI/CD pipeline.