[SOLVED] Is there a way to combine "changes" and "needs" in GitLab CI?

Is there a way to combine "changes" and "needs" in GitLab CI?

I have got a GitLab CI pipeline where I am trying to run backend builds only when there are changes in the corresponding directory. For this I am using the "changes"-rule to check for any modifications.

The backend_build and backend_deploy jobs both check for modifications, but the deployment also needs the backend_build to be run successfully first, for which I am using the "needs" keyword.

Now when changes are done in another folder (e.g. "frontend") I am getting the following error:

'backend_deploy' job needs 'backend_build' job, but 'backend_build' is not in any previous stage

image: maven:3.9-amazoncorretto-17

stages:
  - build
  - deploy

.backend_build_rules:
  rules:
    - changes:
        - backend/**/*
        - .gitlab-ci.yml

backend_build:
  stage: build
  extends: .backend_build_rules
  script:
    - echo "Backend building..."

backend_deploy:
  stage: deploy
  extends: .backend_build_rules
  script:
    - echo "Backend deploying..."
  needs:
    - job: backend_build_job

frontend_build: 
  stage: build
  ...


frontend_deploy:
  stage: deploy
  ...

Does anyone know how I can successfully combine those two keywords?

Solution

You can overcome this behavior via needs:optional keyword:

backend_deploy:
  stage: deploy
  extends: .backend_build_rules
  script:
    - echo "Backend deploying..."
  needs:
    - job: backend_build_job
      optional: true

With this setting the backend_deploy job will always wait for backend_build job, when backend_build presents in the pipeline. According to your configuration backend_deploy and backend_build jobs have the same rules so the case when only backend_deploy will be in the pipeline should not be possible.