Enable DNS AutoScaler for CoreDNS (#3707)

* Enable AutoScaler for CoreDNS

* Only use one template for dns autoscaler

* Rename a few variables for replicas and minimum pods

* Rename a few variables for replicas and minimum pods

* Remove replicas to make autoscale work

* Cleanup kubedns-autoscaler as it has been renamed

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

@@ -8,7 +8,6 @@ metadata:
     k8s-app: coredns{{ coredns_ordinal_suffix | default('') }}
     kubernetes.io/name: "coredns{{ coredns_ordinal_suffix | default('') }}"
 spec:
-  replicas: {{ coredns_replicas }}
   strategy:
     type: RollingUpdate
     rollingUpdate:

roles/kubernetes-apps/ansible/templates/dns-autoscaler.yml.j2

@@ -16,17 +16,17 @@
 apiVersion: extensions/v1beta1
 kind: Deployment
 metadata:
-  name: kubedns-autoscaler
+  name: dns-autoscaler
   namespace: kube-system
   labels:
-    k8s-app: kubedns-autoscaler
+    k8s-app: dns-autoscaler
     kubernetes.io/cluster-service: "true"
     addonmanager.kubernetes.io/mode: Reconcile
 spec:
   template:
     metadata:
       labels:
-        k8s-app: kubedns-autoscaler
+        k8s-app: dns-autoscaler
     spec:
 {% if kube_version is version('v1.11.1', '>=') %}
       priorityClassName: system-cluster-critical
@@ -43,7 +43,7 @@ spec:
           - topologyKey: "kubernetes.io/hostname"
             labelSelector:
               matchLabels:
-                k8s-app: kubedns-autoscaler
+                k8s-app: dns-autoscaler
         nodeAffinity:
           preferredDuringSchedulingIgnoredDuringExecution:
           - weight: 100
@@ -55,7 +55,7 @@ spec:
                 - "true"
       containers:
       - name: autoscaler
-        image: "{{ kubednsautoscaler_image_repo }}:{{ kubednsautoscaler_image_tag }}"
+        image: "{{ dnsautoscaler_image_repo }}:{{ dnsautoscaler_image_tag }}"
         resources:
           requests:
             cpu: "20m"
@@ -63,10 +63,14 @@ spec:
         command:
         - /cluster-proportional-autoscaler
         - --namespace=kube-system
-        - --configmap=kubedns-autoscaler
-        # Should keep target in sync with cluster/addons/dns/kubedns-controller.yaml.base
-        - --target=Deployment/kube-dns
-        - --default-params={"linear":{"nodesPerReplica":{{ kubedns_nodes_per_replica }},"min":{{ kubedns_min_replicas }}}}
+        - --default-params={"linear":{"nodesPerReplica":{{ dns_nodes_per_replica }},"min":{{ dns_min_replicas }}}}
         - --logtostderr=true
         - --v=2
+        - --configmap=dns-autoscaler
+{% if dns_mode in ['coredns', 'coredns_dual'] %}
+        - --target=Deployment/coredns{{ coredns_ordinal_suffix | default('') }}
+{% endif %}
+{% if dns_mode in ['kubedns', 'dnsmasq_kubedns'] %}
+        - --target=Deployment/kube-dns
+{% endif %}
       serviceAccountName: cluster-proportional-autoscaler