kubespray/roles/kubernetes/node/tasks/facts.yml

---
- name: look up docker cgroup driver
  shell: "docker info | grep 'Cgroup Driver' | awk -F': ' '{ print $2; }'"
  register: docker_cgroup_driver_result
  changed_when: false

- set_fact:
    standalone_kubelet: >-
      {%- if inventory_hostname in groups['kube-master'] and inventory_hostname not in groups['kube-node'] -%}true{%- else -%}false{%- endif -%}
    kubelet_cgroup_driver_detected: "{{ docker_cgroup_driver_result.stdout }}"