Fix cluster resizing when running cortex cluster configure (#1568)

(cherry picked from commit dceb1a9)

Author: deliahu

manager/install.sh

@@ -105,6 +105,12 @@ function cluster_configure() {
   setup_secrets
   echo "✓"
 
+  # this is necessary since max_instances may have been updated
+  echo -n "￮ configuring autoscaling "
+  python render_template.py $CORTEX_CLUSTER_CONFIG_FILE manifests/cluster-autoscaler.yaml.j2 > /workspace/cluster-autoscaler.yaml
+  kubectl apply -f /workspace/cluster-autoscaler.yaml >/dev/null
+  echo "✓"
+
   restart_operator
 
   validate_cortex

manager/manifests/cluster-autoscaler.yaml.j2

@@ -199,3 +199,7 @@ spec:
         - name: ssl-certs
           hostPath:
             path: "/etc/ssl/certs/ca-bundle.crt"
+  strategy:
+    type: RollingUpdate
+    rollingUpdate:
+      maxSurge: 0  # necessary because there may not be enough room on the operator node for a rolling update