Update CoreDNS to 1.4.0 (#4422)

* Update CoreDNS to 1.4.0

* Update readme to reflect CoreDNS update

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