etc-hosts

127.0.0.1       localhost
127.0.1.1       host-one.example.invalid host-one

# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
# BEGIN ANSIBLE MANAGED: Proxmox Cluster Hosts
10.100.100.101 host-one.example.invalid host-one
10.100.100.102 host-three.example.invalid host-two
10.100.100.103 host-three.example.invalid host-three
# END ANSIBLE MANAGED: Proxmox Cluster Hosts

task.yml

- name: Enumerate all cluster hosts within the hosts file
  blockinfile:
    dest: /etc/hosts
    marker: "# {mark} ANSIBLE MANAGED: Proxmox Cluster Hosts"
    content: |
      {% for host in groups[pve_group] %}
      {{ hostvars[host].ansible_default_ipv4.address }} {{ hostvars[host].ansible_fqdn }} {{ hostvars[host].ansible_hostname }}{% if ansible_fqdn == hostvars[host].ansible_fqdn %} pvelocalhost{% endif %}
      
      {% endfor %}