kubespray/roles/kubernetes/master/tasks/kubeadm-upgrade.yml

---
- name: kubeadm | Upgrade first master
  command: >-
    timeout -k 600s 600s
    {{ bin_dir }}/kubeadm
    upgrade apply -y {{ kube_version }}
    --config={{ kube_config_dir }}/kubeadm-config.yaml
    --ignore-preflight-errors=all
    --allow-experimental-upgrades
    --allow-release-candidate-upgrades
    --etcd-upgrade=false
    --force
  register: kubeadm_upgrade
  # Retry is because upload config sometimes fails
  retries: 3
  when: inventory_hostname == groups['kube-master']|first
  failed_when: kubeadm_upgrade.rc != 0 and "field is immutable" not in kubeadm_upgrade.stderr
  notify: Master | restart kubelet

# FIXME: https://github.com/kubernetes/kubeadm/issues/1498 remove stdout_lines
# check after issue is fixed
- name: kubeadm | Upgrade other masters
  command: >-
    timeout -k 600s 600s
    {{ bin_dir }}/kubeadm
    upgrade apply -y {{ kube_version }}
    --config={{ kube_config_dir }}/kubeadm-config.yaml
    --ignore-preflight-errors=all
    --allow-experimental-upgrades
    --allow-release-candidate-upgrades
    --etcd-upgrade=false
  register: kubeadm_upgrade
  when: inventory_hostname != groups['kube-master']|first
  failed_when:
    - kubeadm_upgrade.rc != 0
    - '"field is immutable" not in kubeadm_upgrade.stderr'
    - kubeadm_upgrade.stdout_lines | length > 1
  notify: Master | restart kubelet