dynamic runner tag

Variable expansion in tags works.

Simple runner tag can be set as shown:

variables:
  RUNNER_TAG: "staging"
job:
  tags:
    - $RUNNER_TAG  

tags:
  - ${CI_COMMIT_BRANCH}

Not possible to define array of strings as variable:

variables:
  RUNNER_TAG: [ "staging", "test" ]   # LINT ERROR
job:
  tags: $RUNNER_TAGS

How to set a dynamic gitlab job tag with a variable?

It is not possible to detect runner tag during yaml variables expansion because gitlab doesn't schedule jobs. Gitlab-runners periodically connect to Gitlab servers and asks for jobs.

It is possible to check what runner got our job from environment variable:

CI_RUNNER_TAGS=["linux", "docker", "small", "medium"]

and this variable can be used to generate yaml file for new dynamically generated child pipeline.