Templatize the scaling policy for metrics-server

Also update the metrics-server-nanny to use addon resizer 1.8.3 to leverage the
minSizeCluster command line flag. This is a no-op change.

cluster/addons/metrics-server/metrics-server-deployment.yaml

@@ -58,7 +58,7 @@ spec:
           name: https
           protocol: TCP
       - name: metrics-server-nanny
-        image: k8s.gcr.io/addon-resizer:1.8.2
+        image: k8s.gcr.io/addon-resizer:1.8.3
         resources:
           limits:
             cpu: 100m
@@ -81,15 +81,16 @@ spec:
         command:
           - /pod_nanny
           - --config-dir=/etc/config
-          - --cpu=40m
+          - --cpu={{ base_metrics_server_cpu }}
           - --extra-cpu=0.5m
-          - --memory=40Mi
+          - --memory={{ base_metrics_server_memory }}
-          - --extra-memory=4Mi
+          - --extra-memory={{ metrics_server_memory_per_node }}Mi
           - --threshold=5
           - --deployment=metrics-server-v0.2.1
           - --container=metrics-server
           - --poll-period=300000
           - --estimator=exponential
+          - --minClusterSize={{ metrics_server_min_cluster_size }}
       volumes:
         - name: metrics-server-config-volume
           configMap:

cluster/gce/gci/configure-helper.sh

@@ -2399,6 +2399,22 @@ EOF
   fi
   if [[ "${ENABLE_METRICS_SERVER:-}" == "true" ]]; then
     setup-addon-manifests "addons" "metrics-server"
+    base_metrics_server_cpu="40m"
+    base_metrics_server_memory="40Mi"
+    metrics_server_memory_per_node="4"
+    metrics_server_min_cluster_size="16"
+    if [[ "${ENABLE_SYSTEM_ADDON_RESOURCE_OPTIMIZATIONS:-}" == "true" ]]; then
+      # TODO: Set each of the following variables to optimized values.
+      base_metrics_server_cpu="40m"
+      base_metrics_server_memory="40Mi"
+      metrics_server_memory_per_node="4"
+      metrics_server_min_cluster_size="16"
+    fi
+    local -r metrics_server_yaml="${dst_dir}/metrics-server/metrics-server-deployment.yaml"
+    sed -i -e "s@{{ base_metrics_server_cpu }}@${base_metrics_server_cpu}@g" "${metrics_server_yaml}"
+    sed -i -e "s@{{ base_metrics_server_memory }}@${base_metrics_server_memory}@g" "${metrics_server_yaml}"
+    sed -i -e "s@{{ metrics_server_memory_per_node }}@${metrics_server_memory_per_node}@g" "${metrics_server_yaml}"
+    sed -i -e "s@{{ metrics_server_min_cluster_size }}@${metrics_server_min_cluster_size}@g" "${metrics_server_yaml}"
   fi
   if [[ "${ENABLE_NVIDIA_GPU_DEVICE_PLUGIN:-}" == "true" ]]; then
     setup-addon-manifests "addons" "device-plugins/nvidia-gpu"