allow using influxdb existing secret in chronograf (#231)

charts/chronograf/Chart.yaml

 apiVersion: v1
 name: chronograf
-version: 1.1.20
+version: 1.1.21
 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/README.md

@@ -23,7 +23,7 @@ The Chronograf Helm chart uses the [Helm](https://helm.sh) package manager to bo
    ```bash
    helm upgrade --install my-release influxdata/chronograf
    ```
-    
+
    > **Tip**: `--install` can be shortened to `-i`.
 
    This command deploys Chronograf on the Kubernetes cluster using the default configuration. To find parameters you can configure during installation, see [Configure the chart](#configure-the-chart).
@@ -83,6 +83,7 @@ The following table lists configurable parameters, their descriptions, and their
 | `nodeSelector`               | Node labels for pod assignment                                                                            | {}                                          |
 | `tolerations`                | Toleration labels for pod assignment                                                                      | []                                          |
 | `affinity`                   | Affinity settings for pod assignment                                                                      | {}                                          |
+| `influxdb.existingSecret`    | Name of an existing Secrect used to set the environment variables for the InfluxDB user and password. The expected keys in the secret are `influxdb-user` and `influxdb-password`. |
 
 To configure the chart, do either of the following:
 

charts/chronograf/templates/deployment.yaml

@@ -153,6 +153,18 @@ spec:
               key: gen_api_url
 {{- end }}
 {{- end }}
+{{- if .Values.influxdb.existingSecret }}
+        - name: INFLUXDB_USERNAME
+          valueFrom:
+            secretKeyRef:
+              key: influxdb-user
+              name: {{ .Values.influxdb.existingSecret }}
+        - name: INFLUXDB_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              key: influxdb-password
+              name: {{ .Values.influxdb.existingSecret }}
+{{- end }}
 {{- if .Values.envFromSecret }}
         envFrom:
         - secretRef:

charts/chronograf/values.yaml

@@ -135,3 +135,10 @@ envFromSecret: ""
 ## Use Recreate when persistence is enabled
 updateStrategy:
   type: RollingUpdate
+
+influxdb: {}
+  ## Name of an existing Secrect used to set the environment variables for the
+  ## InfluxDB user and password. The expected keys in the secret are
+  ## `influxdb-user` and `influxdb-password`.
+  ##
+  # existingSecret: influxdb-auth