matrix-docker-ansible-deploy/roles/matrix-base/tasks/validate_config.yml

---

- name: (Deprecation) Warn about unused user/group variables
  fail:
    msg: >
      The `{{ item }}` variable defined in your configuration is not used by this playbook anymore.
      User/group creation is now dynamic. You can remove these variables from your configuration, as they have no effect on anything.
  when: "item in vars"
  with_items:
    - 'matrix_user_uid'
    - 'matrix_user_gid'