GitLab: CI_MERGE_REQUEST_LABELS and CI_MERGE_REQUEST_DESCRIPTION not available in pipeline after merge

I’m trying to use the predefined GitLab CI/CD variables CI_MERGE_REQUEST_LABELS and CI_MERGE_REQUEST_DESCRIPTION to control whether the pipeline should execute when merging a Merge Request (MR) into master.

According to the GitLab 17.8 documentation (Predefined CI/CD variables), these variables should be available inside the pipeline. However, when running env after the merge, they are not present in the environment.

I created an MR with:

• Label: NO_DEPLOY
• Description: THIS_IS_A_DESCRIPTION

Here’s a simple .gitlab-ci.yml I used for debugging:

image: alpine:latest

stages:
  - test

test-merge-request:
  stage: test
  script:
    - $CI_MERGE_REQUEST_DESCRIPTION
    - $CI_MERGE_REQUEST_LABELS
    - env
  rules:
    - if: '$CI_PIPELINE_SOURCE == "push" && $CI_COMMIT_BRANCH == "master"'

Issue: After merging the MR into master, neither CI_MERGE_REQUEST_LABELS nor CI_MERGE_REQUEST_DESCRIPTION appear in the pipeline logs.

Questions:

1. Are these variables unavailable in pipelines triggered by a merge?
2. Is there any extra configuration needed to ensure these variables are available?

Any insights or solutions would be appreciated.

The CI_MERGE_REQUEST_LABELS and CI_MERGE_REQUEST_DESCRIPTION variables are only available for merge request pipelines, i.e. $CI_PIPELINE_SOURCE == "merge_request_event", when the merge request is open (See Predefined variables for merge request pipelines).

In your debug example, you check that CI_PIPELINE_SOURCE is push, in which case the pipeline trigger will be the merge commit instead of a merge request event. Thus, the merge request related CI variables are not defined.