ansible-role-ssh_host_key/tasks/setup.yml

---

- name: set ssh_host_key_ed25519_public from setup
  set_fact:
    ssh_host_key_ed25519_public: "{{ ansible_ssh_host_key_ed25519_public }}"
  changed_when: ssh_host_key_ed25519_public != ansible_ssh_host_key_ed25519_public