Update CoreDNS to 1.4.0 (#4422)

* Update CoreDNS to 1.4.0

* Update readme to reflect CoreDNS update

README.md

@@ -129,7 +129,7 @@ Supported Components
 -   Application
     -   [cephfs-provisioner](https://github.com/kubernetes-incubator/external-storage) v2.1.0-k8s1.11
     -   [cert-manager](https://github.com/jetstack/cert-manager) v0.5.2
-    -   [coredns](https://github.com/coredns/coredns) v1.2.6
+    -   [coredns](https://github.com/coredns/coredns) v1.4.0
     -   [ingress-nginx](https://github.com/kubernetes/ingress-nginx) v0.21.0
 
 Note: The list of validated [docker versions](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG-1.13.md) was updated to 1.11.1, 1.12.1, 1.13.1, 17.03, 17.06, 17.09, 18.06. kubeadm now properly recognizes Docker 18.09.0 and newer, but still treats 18.06 as the default supported version. The kubelet might break on docker's non-standard version numbering (it no longer uses semantic versioning). To ensure auto-updates don't break your cluster look into e.g. yum versionlock plugin or apt pin).
@@ -155,9 +155,9 @@ Requirements
     or command parameters `--become or -b` should be specified.
 
 Hardware:        
-These limits are safe guarded by Kubespray. Actual requirements for your workload can differ. For a sizing guide go to the [Building Large Clusters](https://kubernetes.io/docs/setup/cluster-large/#size-of-master-and-master-components) guide. 
+These limits are safe guarded by Kubespray. Actual requirements for your workload can differ. For a sizing guide go to the [Building Large Clusters](https://kubernetes.io/docs/setup/cluster-large/#size-of-master-and-master-components) guide.
 
--   Master 
+-   Master
     - Memory: 1500 MB
 -   Node
     - Memory: 1024 MB

roles/download/defaults/main.yml

@@ -202,7 +202,7 @@ multus_image_tag: "{{ multus_version }}"
 nginx_image_repo: nginx
 nginx_image_tag: 1.13
 
-coredns_version: "1.2.6"
+coredns_version: "1.4.0"
 coredns_image_repo: "coredns/coredns"
 coredns_image_tag: "{{ coredns_version }}"
 

roles/kubernetes-apps/ansible/templates/coredns-config.yml.j2

@@ -22,9 +22,9 @@ data:
         }
         prometheus :9153
 {% if resolvconf_mode == 'host_resolvconf' and upstream_dns_servers is defined and upstream_dns_servers|length > 0 %}
-        proxy . {{ upstream_dns_servers.join(' ') }}
+        forward . {{ upstream_dns_servers.join(' ') }}
 {% else %}
-        proxy . /etc/resolv.conf
+        forward . /etc/resolv.conf
 {% endif %}
         cache 30
         loop

roles/kubernetes-apps/ansible/templates/coredns-deployment.yml.j2

@@ -95,6 +95,15 @@ spec:
           timeoutSeconds: 5
           successThreshold: 1
           failureThreshold: 5
+        readinessProbe:
+          httpGet:
+            path: /health
+            port: 8080
+            scheme: HTTP
+          initialDelaySeconds: 60
+          timeoutSeconds: 5
+          successThreshold: 1
+          failureThreshold: 5
       dnsPolicy: Default
       volumes:
         - name: config-volume