kubespray/roles/kubernetes/preinstall/tasks/etchosts.yml

---
- name: Hosts | populate inventory into hosts file
  blockinfile:
    dest: /etc/hosts
    block: |-
      {% for item in (groups['k8s-cluster'] + groups['etcd'] + groups['calico-rr']|default([]))|unique -%}{{ hostvars[item]['access_ip'] | default(hostvars[item]['ip'] | default(hostvars[item]['ansible_default_ipv4']['address'])) }}{% if (item != hostvars[item]['ansible_hostname']) %} {{ hostvars[item]['ansible_hostname'] }} {{ hostvars[item]['ansible_hostname'] }}.{{ dns_domain }}{% endif %} {{ item }} {{ item }}.{{ dns_domain }}
      {% endfor %}
    state: present
    create: yes
    backup: yes
    marker: "# Ansible inventory hosts {mark}"

- name: Hosts | populate kubernetes loadbalancer address into hosts file
  lineinfile:
    dest: /etc/hosts
    regexp: ".*{{ apiserver_loadbalancer_domain_name }}$"
    line: "{{ loadbalancer_apiserver.address }} {{ apiserver_loadbalancer_domain_name| default('lb-apiserver.kubernetes.local') }}"
    state: present
    backup: yes
  when:
    - loadbalancer_apiserver is defined
    - loadbalancer_apiserver.address is defined
    - apiserver_loadbalancer_domain_name is defined

- name: Hosts | localhost ipv4 in hosts file
  lineinfile:
    dest: /etc/hosts
    line: "127.0.0.1 localhost localhost.localdomain"
    regexp: '^127.0.0.1.*$'
    state: present
    backup: yes

- name: Hosts | localhost ipv6 in hosts file
  lineinfile:
    dest: /etc/hosts
    line: "::1 localhost6 localhost6.localdomain"
    regexp: '^::1.*$'
    state: present
    backup: yes