kubespray/roles/kubernetes/control-plane/tasks/define-first-kube-control.yml

---

- name: Check which kube-control nodes are already members of the cluster
  command: "{{ bin_dir }}/kubectl get nodes --selector=node-role.kubernetes.io/control-plane -o json"
  register: kube_control_planes_raw
  ignore_errors: yes
  changed_when: false

- name: Set fact joined_control_planes
  set_fact:
    joined_control_planes: "{{ ((kube_control_planes_raw.stdout | from_json)['items']) | default([]) | map(attribute='metadata') | map(attribute='name') | list }}"
  delegate_to: "{{ item }}"
  loop: "{{ groups['kube_control_plane'] }}"
  when: kube_control_planes_raw is succeeded
  run_once: yes

- name: Set fact first_kube_control_plane
  set_fact:
    first_kube_control_plane: "{{ joined_control_planes | default([]) | first | default(groups['kube_control_plane'] | first) }}"