[Nodelocal DNS cache] Mount host /run/xtables.lock in nodelocaldns container (#4074)

* Mount host /run/xtables.lock in nodelocaldns container

* fix typo in nodelocaldns daemonset manifest yml

* Add prometheus scrape annotation, updateStrategy and reduce termination grace period

* fix indentation

* actually fix it..

* Bump k8s-dns-node-cache tag to 1.15.1 (fixes https://github.com/kubernetes/dns/issues/282)

roles/kubernetes-apps/ansible/templates/nodelocaldns-daemonset.yml.j2

@@ -13,8 +13,11 @@ spec:
       k8s-app: nodelocaldns
   template:
     metadata:
-       labels:
-          k8s-app: nodelocaldns
+      labels:
+        k8s-app: nodelocaldns
+      annotations:
+        prometheus.io/scrape: 'true'
+        prometheus.io/port: '9253'
     spec:
 {% if kube_version is version('v1.11.1', '>=') %}
       priorityClassName: system-cluster-critical
@@ -62,6 +65,8 @@ spec:
         volumeMounts:
         - name: config-volume
           mountPath: /etc/coredns
+        - name: xtables-lock
+          mountPath: /run/xtables.lock
       volumes:
         - name: config-volume
           configMap:
@@ -69,4 +74,14 @@ spec:
             items:
             - key: Corefile
               path: Corefile
-      terminationGracePeriodSeconds: 30
+        - name: xtables-lock
+          hostPath:
+            path: /run/xtables.lock
+            type: FileOrCreate
+      # Minimize downtime during a rolling upgrade or deletion; tell Kubernetes to do a "force
+      # deletion": https://kubernetes.io/docs/concepts/workloads/pods/pod/#termination-of-pods.
+      terminationGracePeriodSeconds: 0
+  updateStrategy:
+    rollingUpdate:
+      maxUnavailable: {{ serial | default('20%') }}
+    type: RollingUpdate