Trigger gitlab downstream pipeline from a upstream pipeline in a multi-project using trigger, rules and custom configuration variables

Question

I have this scenario where I want to run the trigger in build stage only when $FLAG variable has been set by the .pre stage. However, the build stage never runs.

How should I conditionally trigger a downstream pipeline?

checkArtifactPresent:
  stage: .pre
  script:
    - >
      set +e;
      if curl -s -S -f $NEXUS_RAW_PICKER_REPOSITORY/${PRODUCT_FLAVOR}/${PRODUCT_FLAVOR}-${BUILD_TYPE}v${PICKER_TEMPLATE_TAG}.apk --output ${PRODUCT_FLAVOR}-${BUILD_TYPE}v${PICKER_TEMPLATE_TAG}.apk;
      then
        export FLAG= true;
      fi

buildArtifact:
  stage: build
  only:
   variables:
     - $FLAG
  trigger:
   project: dev/project_name
   strategy: depend

Answer 1

You could use dynamic child pipelines. (https://docs.gitlab.com/ee/ci/parent_child_pipelines.html#dynamic-child-pipelines).

You could create a job for triggering your job "buildArtifact" in a yml-file created with jsonnet in your "checkArtifactPresent". With using "--ext-str" or "--ext-code" in jsonnet. You can control the yml-file creation (https://jsonnet.org/learning/tutorial.html#parameterize-entire-config).

Read more https://jsonnet.org/