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/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 }}"