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

---
- name: check resolvconf
  shell: which resolvconf
  register: resolvconf
  ignore_errors: yes
  changed_when: false

- set_fact:
    resolvconf: >-
      {%- if resolvconf.rc == 0 -%}true{%- else -%}false{%- endif -%}

- set_fact:
    private_domains: |-
      {% for d in [ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([]) -%}
      {{dns_domain}}.{{d}}./{{d}}.{{d}}./com.{{d}}./
      {%- endfor %}
    default_resolver: >-
      {%- if cloud_provider is defined and cloud_provider == 'gce' -%}169.254.169.254{%- else -%}8.8.8.8{%- endif -%}

- name: check kubelet
  stat:
    path: "{{ bin_dir }}/kubelet"
  register: kubelet
  changed_when: false

- name: check if early DNS configuration stage
  set_fact:
    dns_early: >-
      {%- if kubelet.stat.exists -%}false{%- else -%}true{%- endif -%}

- name: target resolv.conf files
  set_fact:
    resolvconffile: /etc/resolv.conf
    base: >-
      {%- if resolvconf|bool -%}/etc/resolvconf/resolv.conf.d/base{%- endif -%}
    head: >-
      {%- if resolvconf|bool -%}/etc/resolvconf/resolv.conf.d/head{%- endif -%}
  when: ansible_os_family != "CoreOS"

- name: target temporary resolvconf cloud init file (CoreOS)
  set_fact: resolvconffile=/tmp/resolveconf_cloud_init_conf
  when: ansible_os_family == "CoreOS"

- name: target dhclient conf/hook files for Red Hat family
  set_fact:
    dhclientconffile: /etc/dhclient.conf
    dhclienthookfile: /etc/dhcp/dhclient.d/zdnsupdate.sh
  when: ansible_os_family == "RedHat"

- name: target dhclient conf/hook files for Debian family
  set_fact:
    dhclientconffile: /etc/dhcp/dhclient.conf
    dhclienthookfile: /etc/dhcp/dhclient-exit-hooks.d/zdnsupdate
  when: ansible_os_family == "Debian"

- name: generate search domains to resolvconf
  set_fact:
    searchentries:
      search {{ ([ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([])) | join(' ') }}
    domainentry:
      domain {{ dns_domain }}
    supersede_search:
      supersede domain-search "{{ ([ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([])) | join('", "') }}";
    supersede_domain:
      supersede domain-name "{{ dns_domain }}";

- name: decide on dns server IP
  set_fact:
    dns_server_real: >-
      {%- if dns_early|bool -%}{{default_resolver}}{%- else -%}{{dns_server}}{%- endif -%}

- name: pick dnsmasq cluster IP or default resolver
  set_fact:
    dnsmasq_server: |-
      {%- if skip_dnsmasq|bool and not dns_early|bool -%}
        {{ [ skydns_server ] + upstream_dns_servers|default([]) }}
      {%- elif dns_early|bool -%}
        {{ [ dns_server_real ] + upstream_dns_servers|default([]) }}
      {%- else -%}
        {{ [ dns_server ] }}
      {%- endif -%}

- name: generate nameservers to resolvconf
  set_fact:
    nameserverentries:
      nameserver {{( dnsmasq_server|default([]) + nameservers|default([])) | join(',nameserver ')}}
    prepend_nameserver:
      prepend domain-name-servers {{( dnsmasq_server|default([]) + nameservers|default([])) | join(', ') }};