Merge pull request #667 from bogdando/fix_dns
Rework DNS stack to meet hostnet pods needs
This commit is contained in:
Bogdan Dobrelya
GitHub
commit
4e721bfd9d
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@ -38,6 +38,17 @@ or `8.8.8.8`. And domain is set to the default ``dns_domain`` value as well.
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Later, the nameservers will be reconfigured to the DNS service IP that Kargo
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configures for K8s cluster.
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Also note, existing records will be purged from the `/etc/resolv.conf`,
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including base/head/cloud-init config files and those that come from dhclient.
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This is required for hostnet pods networking and for [kubelet to not exceed search domains
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limits](https://github.com/kubernetes/kubernetes/issues/9229).
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New search, nameserver records and options will be defined from the aforementioned vars:
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* Via resolvconf's head file, if resolvconf installed.
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* Via dhclient's DNS update hook.
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* Via cloud-init (CoreOS only).
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* Statically in the `/etc/resolv.conf`, if none of above is applicable.
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DNS configuration details
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-------------------------
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@ -2,9 +2,10 @@
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command: /bin/true
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notify:
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- Preinstall | reload network
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- Preinstall | update resolvconf
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- Preinstall | reload kubelet
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when: ansible_os_family != "CoreOS"
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# FIXME(bogdando) https://github.com/projectcalico/felix/issues/1185
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- name: Preinstall | reload network
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service:
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name: >-
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@ -14,14 +15,7 @@
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networking
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{%- endif %}
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state: restarted
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when: ansible_os_family != "RedHat" and ansible_os_family != "CoreOS"
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- name: Preinstall | update resolvconf
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command: /bin/true
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notify:
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- Preinstall | reload resolvconf
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- Preinstall | reload kubelet
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when: ansible_os_family != "CoreOS"
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when: ansible_os_family != "CoreOS" and kube_network_plugin not in ['canal', 'calico']
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- name: Preinstall | update resolvconf for CoreOS
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command: /bin/true
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@ -30,10 +24,6 @@
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- Preinstall | reload kubelet
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when: ansible_os_family == "CoreOS"
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- name: Preinstall | reload resolvconf
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command: /sbin/resolvconf -u
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ignore_errors: true
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- name: Preinstall | apply resolvconf cloud-init
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command: /usr/bin/coreos-cloudinit --from-file {{ resolveconf_cloud_init_conf }}
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when: ansible_os_family == "CoreOS"
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33
roles/kubernetes/preinstall/tasks/dhclient-hooks.yml
Normal file
33
roles/kubernetes/preinstall/tasks/dhclient-hooks.yml
Normal file
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@ -0,0 +1,33 @@
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---
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- name: Configure dhclient to prepend nameservers and supersede search/domain
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blockinfile:
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block: |-
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{% for item in [ supersede_domain, supersede_search, prepend_nameserver ] -%}
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{{ item }}
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{% endfor %}
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dest: "{{dhclientconffile}}"
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create: yes
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state: present
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insertbefore: BOF
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backup: yes
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follow: yes
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marker: "# Ansible entries {mark}"
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notify: Preinstall | restart network
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- name: Configue dhclient hooks for resolv.conf (non-RH)
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template:
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src: dhclient_dnsupdate.sh.j2
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dest: "{{ dhclienthookfile }}"
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owner: root
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mode: 0755
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notify: Preinstall | restart network
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when: ansible_os_family != "RedHat"
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- name: Configue dhclient hooks for resolv.conf (RH-only)
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template:
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src: dhclient_dnsupdate_rh.sh.j2
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dest: "{{ dhclienthookfile }}"
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owner: root
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mode: 0755
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notify: Preinstall | restart network
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when: ansible_os_family == "RedHat"
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@ -1,120 +1,34 @@
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---
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- name: check resolvconf
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shell: which resolvconf
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register: resolvconf
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ignore_errors: yes
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changed_when: false
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tags: facts
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- name: check kubelet
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stat:
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path: "{{ bin_dir }}/kubelet"
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register: kubelet
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changed_when: false
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tags: facts
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- name: check if early DNS configuration stage
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set_fact:
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dns_early: >-
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{%- if kubelet.stat.exists -%}false{%- else -%}true{%- endif -%}
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tags: facts
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- name: target resolv.conf file
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set_fact:
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resolvconffile: >-
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{%- if resolvconf.rc == 0 -%}/etc/resolvconf/resolv.conf.d/head{%- else -%}/etc/resolv.conf{%- endif -%}
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when: ansible_os_family != "CoreOS"
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tags: facts
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- name: target temporary resolvconf cloud init file
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set_fact:
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resolvconffile: /tmp/resolveconf_cloud_init_conf
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when: ansible_os_family == "CoreOS"
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tags: facts
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- name: create temporary resolveconf cloud init file
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command: cp -f /etc/resolv.conf "{{ resolvconffile }}"
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when: ansible_os_family == "CoreOS"
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- name: generate search domains to resolvconf
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set_fact:
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searchentries:
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"{{ ([ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([])) | join(' ') }}"
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tags: facts
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- name: decide on dns server IP
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set_fact:
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dns_server_real: >-
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{%- if dns_early|bool -%}{{default_resolver}}{%- else -%}{{dns_server}}{%- endif -%}
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- name: pick dnsmasq cluster IP or default resolver
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set_fact:
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dnsmasq_server: |-
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{%- if skip_dnsmasq|bool and not dns_early|bool -%}
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{{ [ skydns_server ] + upstream_dns_servers|default([]) }}
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{%- elif dns_early|bool -%}
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{{ [ dns_server_real ] + upstream_dns_servers|default([]) }}
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{%- else -%}
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{{ [ dns_server ] }}
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{%- endif -%}
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tags: facts
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- name: generate nameservers to resolvconf
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set_fact:
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nameserverentries:
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"{{ dnsmasq_server|default([]) + nameservers|default([]) }}"
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tags: facts
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- name: Remove search and nameserver options from resolvconf head
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- name: Remove search/domain/nameserver options
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lineinfile:
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dest: /etc/resolvconf/resolv.conf.d/head
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dest: "{{item[0]}}"
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state: absent
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regexp: "^{{ item }}.*$"
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regexp: "^{{ item[1] }}.*$"
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backup: yes
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follow: yes
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with_items:
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- search
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- nameserver
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when: resolvconf.rc == 0
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notify: Preinstall | update resolvconf
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with_nested:
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- "{{ [resolvconffile] + [base|default('')] + [head|default('')] }}"
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- [ 'search ', 'nameserver ', 'domain ', 'options ' ]
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notify: Preinstall | restart network
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- name: Remove search and nameserver options from resolvconf cloud init temporary file
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lineinfile:
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dest: "{{resolvconffile}}"
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state: absent
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regexp: "^{{ item }}.*$"
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backup: yes
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follow: yes
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with_items:
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- search
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- nameserver
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when: ansible_os_family == "CoreOS"
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notify: Preinstall | update resolvconf for CoreOS
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- name: Add search domains to resolvconf file
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lineinfile:
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line: "search {{searchentries}}"
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dest: "{{resolvconffile}}"
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state: present
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insertbefore: BOF
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backup: yes
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follow: yes
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notify: Preinstall | update resolvconf
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- name: Add nameservers to resolv.conf
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- name: Add domain/search/nameservers to resolv.conf
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blockinfile:
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dest: "{{resolvconffile}}"
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block: |-
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{% for item in nameserverentries -%}
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nameserver {{ item }}
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{% for item in [domainentry] + [searchentries] + nameserverentries.split(',') -%}
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{{ item }}
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{% endfor %}
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state: present
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insertafter: "^search default.svc.*$"
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insertbefore: BOF
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create: yes
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backup: yes
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follow: yes
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marker: "# Ansible nameservers {mark}"
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notify: Preinstall | update resolvconf
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marker: "# Ansible entries {mark}"
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notify: Preinstall | restart network
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- name: Add options to resolv.conf
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lineinfile:
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@ -129,30 +43,7 @@
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- ndots:{{ ndots }}
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- timeout:2
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- attempts:2
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notify: Preinstall | update resolvconf
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- name: Remove search and nameserver options from resolvconf base
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lineinfile:
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dest: /etc/resolvconf/resolv.conf.d/base
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state: absent
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regexp: "^{{ item }}.*$"
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backup: yes
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follow: yes
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with_items:
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- search
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- nameserver
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when: resolvconf.rc == 0
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notify: Preinstall | update resolvconf
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- name: disable resolv.conf modification by dhclient
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copy: src=dhclient_nodnsupdate dest=/etc/dhcp/dhclient-enter-hooks.d/znodnsupdate mode=0755
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notify: Preinstall | restart network
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when: ansible_os_family == "Debian"
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- name: disable resolv.conf modification by dhclient
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copy: src=dhclient_nodnsupdate dest=/etc/dhcp/dhclient.d/nodnsupdate mode=u+x
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notify: Preinstall | restart network
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when: ansible_os_family == "RedHat"
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- name: get temporary resolveconf cloud init file content
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command: cat {{ resolvconffile }}
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@ -167,3 +58,7 @@
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mode: 0644
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notify: Preinstall | update resolvconf for CoreOS
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when: ansible_os_family == "CoreOS"
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- include: dhclient-hooks.yml
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when: ansible_os_family != "CoreOS"
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tags: [bootstrap-os, resolvconf]
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@ -49,6 +49,6 @@
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etcd_after_v3: etcd_version | version_compare("v3.0.0", ">=")
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- set_fact:
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etcd_container_bin_dir: "{% if etcd_after_v3 %}/usr/local/bin/{% else %}/{% endif %}"
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- set_fact:
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default_resolver: >-
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{%- if cloud_provider is defined and cloud_provider == 'gce' -%}169.254.169.254{%- else -%}8.8.8.8{%- endif -%}
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- include: set_resolv_facts.yml
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tags: [bootstrap-os, resolvconf, facts]
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88
roles/kubernetes/preinstall/tasks/set_resolv_facts.yml
Normal file
88
roles/kubernetes/preinstall/tasks/set_resolv_facts.yml
Normal file
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@ -0,0 +1,88 @@
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---
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- name: check resolvconf
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shell: which resolvconf
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register: resolvconf
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ignore_errors: yes
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changed_when: false
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- set_fact:
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resolvconf: >-
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{%- if resolvconf.rc == 0 -%}true{%- else -%}false{%- endif -%}
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- set_fact:
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private_domains: |-
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{% for d in [ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([]) -%}
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{{dns_domain}}.{{d}}./{{d}}.{{d}}./com.{{d}}./
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{%- endfor %}
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default_resolver: >-
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{%- if cloud_provider is defined and cloud_provider == 'gce' -%}169.254.169.254{%- else -%}8.8.8.8{%- endif -%}
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- name: check kubelet
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stat:
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path: "{{ bin_dir }}/kubelet"
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register: kubelet
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changed_when: false
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- name: check if early DNS configuration stage
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set_fact:
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dns_early: >-
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{%- if kubelet.stat.exists -%}false{%- else -%}true{%- endif -%}
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- name: target resolv.conf files
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set_fact:
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resolvconffile: /etc/resolv.conf
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base: >-
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{%- if resolvconf|bool -%}/etc/resolvconf/resolv.conf.d/base{%- endif -%}
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head: >-
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{%- if resolvconf|bool -%}/etc/resolvconf/resolv.conf.d/head{%- endif -%}
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when: ansible_os_family != "CoreOS"
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- name: target temporary resolvconf cloud init file (CoreOS)
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set_fact: resolvconffile=/tmp/resolveconf_cloud_init_conf
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when: ansible_os_family == "CoreOS"
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- name: target dhclient conf/hook files for Red Hat family
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set_fact:
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dhclientconffile: /etc/dhclient.conf
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dhclienthookfile: /etc/dhcp/dhclient.d/zdnsupdate.sh
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when: ansible_os_family == "RedHat"
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- name: target dhclient conf/hook files for Debian family
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set_fact:
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dhclientconffile: /etc/dhcp/dhclient.conf
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dhclienthookfile: /etc/dhcp/dhclient-exit-hooks.d/zdnsupdate
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when: ansible_os_family == "Debian"
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- name: generate search domains to resolvconf
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set_fact:
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searchentries:
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search {{ ([ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([])) | join(' ') }}
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domainentry:
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domain {{ dns_domain }}
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supersede_search:
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supersede domain-search "{{ ([ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([])) | join('", "') }}";
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supersede_domain:
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supersede domain-name "{{ dns_domain }}";
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- name: decide on dns server IP
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set_fact:
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dns_server_real: >-
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{%- if dns_early|bool -%}{{default_resolver}}{%- else -%}{{dns_server}}{%- endif -%}
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- name: pick dnsmasq cluster IP or default resolver
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set_fact:
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dnsmasq_server: |-
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{%- if skip_dnsmasq|bool and not dns_early|bool -%}
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{{ [ skydns_server ] + upstream_dns_servers|default([]) }}
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{%- elif dns_early|bool -%}
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{{ [ dns_server_real ] + upstream_dns_servers|default([]) }}
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{%- else -%}
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{{ [ dns_server ] }}
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{%- endif -%}
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- name: generate nameservers to resolvconf
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set_fact:
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nameserverentries:
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nameserver {{( dnsmasq_server|default([]) + nameservers|default([])) | join(',nameserver ')}}
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prepend_nameserver:
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prepend domain-name-servers {{( dnsmasq_server|default([]) + nameservers|default([])) | join(', ') }};
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@ -0,0 +1,13 @@
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#!/bin/sh
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#
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# Prepend resolver options to /etc/resolv.conf after dhclient`
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# regenerates the file. See man (5) resolver for more details.
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#
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if [ $reason = "BOUND" ]; then
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if [ -n "$new_domain_search" -o -n "$new_domain_name_servers" ]; then
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RESOLV_CONF=$(cat /etc/resolv.conf)
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OPTIONS="options timeout:2\noptions attempts:2\noptions ndots:{{ ndots }}"
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printf "%b\n" "$RESOLV_CONF\n$OPTIONS" > /etc/resolv.conf
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fi
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fi
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@ -0,0 +1,17 @@
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#!/bin/sh
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#
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# Prepend resolver options to /etc/resolv.conf after dhclient`
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# regenerates the file. See man (5) resolver for more details.
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#
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zdnsupdate_config() {
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if [ -n "$new_domain_search" -o -n "$new_domain_name_servers" ]; then
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RESOLV_CONF=$(cat /etc/resolv.conf)
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OPTIONS="options timeout:2\noptions attempts:2\noptions ndots:{{ ndots }}"
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echo -e "$RESOLV_CONF\n$OPTIONS" > /etc/resolv.conf
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fi
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}
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zdnsupdate_restore() {
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:
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}
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