allow using recreate when updating deployment (#243)

charts/chronograf/Chart.yaml

 apiVersion: v1
 name: chronograf
-version: 1.1.19
+version: 1.1.20
 appVersion: 1.8.8
 description: Open-source web application written in Go and React.js that provides
   the tools to visualize your monitoring data and easily create alerting and automation

charts/chronograf/templates/deployment.yaml

@@ -9,6 +9,11 @@ metadata:
     heritage: "{{ .Release.Service }}"
 spec:
   replicas: {{ .Values.service.replicas }}
+  strategy:
+    type: {{ .Values.updateStrategy.type }}
+    {{- if eq .Values.updateStrategy.type "Recreate" }}
+    rollingUpdate: null
+    {{- end }}
   selector:
     matchLabels:
       app: {{ template "chronograf.fullname" . }}

charts/chronograf/values.yaml

@@ -131,3 +131,7 @@ envFromSecret: ""
 # - name: chronograf-output-influxdb2
 #   mountPath: /var/lib/chronograf/conf.d
 #   subPath: influxdb2.conf
+
+## Use Recreate when persistence is enabled
+updateStrategy:
+  type: RollingUpdate