kubespray/roles/vault/tasks/shared/check_etcd.yml

---

- name: check_etcd | Check if etcd is up and reachable
  uri:
    url: "{{ vault_etcd_url }}/health"
    validate_certs: no
  until: vault_etcd_health_check.status == 200 or vault_etcd_health_check.status == 401
  retries: 10
  delay: 2
  delegate_to: "{{groups['etcd'][0]}}"
  run_once: true
  failed_when: false
  register: vault_etcd_health_check

- name: check_etcd | Set fact based off the etcd_health_check response
  set_fact:
    vault_etcd_available: "{{ vault_etcd_health_check.get('json', {}).get('health')|bool  }}"

- name: check_etcd | Fail if etcd is not available and needed
  fail:
    msg: >
         Unable to start Vault cluster! Etcd is not available at
         {{ vault_etcd_url }} however it is needed by Vault as a backend.
  when: vault_etcd_needed|d() and not vault_etcd_available