Add support for running a nodelocal dns cache (#3861)

* Add support for running a nodelocal dns cache

After encountering dns issues in a cluster I was recently working on I
noticed Kubernetes 1.13 introduced support for running a nodelocal dns
cache.

I believe this can usefull for more people.

73b548db06
https://github.com/kubernetes/enhancements/blob/master/keps/sig-network/0030-nodelocal-dns-cache.md

* Add requested changes

* Add additional requested changes + documentation

* Add requested changes after review

* Replace incorrect variable

roles/kubernetes-apps/ansible/tasks/cleanup_dns.yml

@@ -13,6 +13,19 @@
   tags:
     - upgrade
 
+- name: Kubernetes Apps | Delete old nodelocalDNS resources
+  kube:
+    name: "nodelocaldns"
+    namespace: "kube-system"
+    kubectl: "{{ bin_dir }}/kubectl"
+    resource: "{{ item }}"
+    state: absent
+  with_items:
+    - 'deamonset'
+    - 'configmap'
+  tags:
+    - upgrade
+
 - name: Kubernetes Apps | Delete kubeadm CoreDNS
   kube:
     name: "coredns"

roles/kubernetes-apps/ansible/tasks/main.yml

@@ -20,6 +20,7 @@
     - dnsmasq
     - coredns
     - kubedns
+    - nodelocaldns
 
 - name: Kubernetes Apps | CoreDNS
   import_tasks: "tasks/coredns.yml"
@@ -29,6 +30,14 @@
   tags:
     - coredns
 
+- name: Kubernetes Apps | nodelocalDNS
+  import_tasks: "tasks/nodelocaldns.yml"
+  when:
+    - enable_nodelocaldns == True
+    - inventory_hostname == groups['kube-master'] | first
+  tags:
+    - nodelocaldns
+
 - name: Kubernetes Apps | KubeDNS
   import_tasks: "tasks/kubedns.yml"
   when:
@@ -49,6 +58,7 @@
     - "{{ kubedns_manifests.results | default({}) }}"
     - "{{ coredns_manifests.results | default({}) }}"
     - "{{ coredns_secondary_manifests.results | default({}) }}"
+    - "{{ nodelocaldns_manifests.results | default({}) }}"
   when:
     - dns_mode != 'none'
     - inventory_hostname == groups['kube-master'][0]
@@ -61,6 +71,7 @@
     - dnsmasq
     - coredns
     - kubedns
+    - nodelocaldns
   loop_control:
     label: "{{ item.item.file }}"
 

roles/kubernetes-apps/ansible/tasks/nodelocaldns.yml

@@ -0,0 +1,18 @@
+---
+- name: Kubernetes Apps | Lay Down nodelocaldns Template
+  template:
+    src: "{{ item.file }}.j2"
+    dest: "{{ kube_config_dir }}/{{ item.file }}"
+  with_items:
+    - { name: nodelocaldns, file: nodelocaldns-config.yml, type: configmap }
+    - { name: nodelocaldns, file: nodelocaldns-sa.yml, type: sa }
+    - { name: nodelocaldns, file: nodelocaldns-deamonset.yml, type: daemonset }
+  register: nodelocaldns_manifests
+  vars:
+    clusterIP: "{{ skydns_server }}"
+    secondaryclusterIP: "{{ skydns_server_secondary }}"
+  when:
+    - enable_nodelocaldns == True
+    - inventory_hostname == groups['kube-master'] | first
+  tags:
+    - nodelocaldns