kubespray/roles/network_plugin/tasks/flannel.yml

---
- name: Flannel | Write flannel configuration
  template:
    src: flannel/network.json
    dest: /etc/flannel-network.json
    backup: yes
  when: inventory_hostname in groups['kube-node']

- name: Flannel | Create flannel pod manifest
  template:
    src: flannel/flannel-pod.yml
    dest: /etc/kubernetes/manifests/flannel-pod.manifest
  notify: delete default docker bridge

- name: Flannel | Wait for flannel subnet.env file presence
  wait_for:
    path: /run/flannel/subnet.env
    delay: 5

- name: Get flannel_subnet from subnet.env
  shell: cat /run/flannel/subnet.env | awk -F'=' '$1 == "FLANNEL_SUBNET" {print $2}'
  register: flannel_subnet_output
  changed_when: false

- set_fact:
    flannel_subnet: "{{ flannel_subnet_output.stdout }}"

- name: Get flannel_mtu from subnet.env
  shell: cat /run/flannel/subnet.env | awk -F'=' '$1 == "FLANNEL_MTU" {print $2}'
  register: flannel_mtu_output
  changed_when: false

- set_fact:
    flannel_mtu: "{{ flannel_mtu_output.stdout }}"