[stable/kapacitor] Use an existing secret for the InfluxDB auth (#19594)

stable/kapacitor/Chart.yaml

 apiVersion: v1
 name: kapacitor
-version: 1.1.4
+version: 1.2.0
 appVersion: 1.5.2
 description: InfluxDB's native data processing engine. It can process both stream
   and batch data from InfluxDB.

stable/kapacitor/README.md

@@ -62,6 +62,7 @@ The following table lists the configurable parameters of the Kapacitor chart and
 | `resources.limits.cpu` | Kapacitor cpu limit | `2` |
 | `envVars` | Environment variables to set initial Kapacitor configuration (https://hub.docker.com/_/kapacitor/) | `{}` |
 | `influxURL` | InfluxDB url used to interact with Kapacitor (also can be set with ```envVars.KAPACITOR_INFLUXDB_0_URLS_0```) | `http://influxdb-influxdb.tick:8086` |
+| `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`. |
 
 The configurable parameters of the Kapacitor chart and the default values are listed in `values.yaml`.
 

stable/kapacitor/templates/deployment.yaml

@@ -29,6 +29,18 @@ spec:
         - name: {{ $key }}
           value: {{ $val | quote }}
         {{- end }}
+        {{- if .Values.existingSecret }}
+        - name: KAPACITOR_INFLUXDB_0_USERNAME
+          valueFrom:
+            secretKeyRef:
+              key: influxdb-user
+              name: {{ .Values.existingSecret }}
+        - name: KAPACITOR_INFLUXDB_0_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              key: influxdb-password
+              name: {{ .Values.existingSecret }}
+        {{- end }}
         ports:
         - containerPort: 9092
         volumeMounts:

stable/kapacitor/values.yaml

@@ -60,3 +60,9 @@ resources:
 ## ref: https://docs.influxdata.com/kapacitor/v1.1/introduction/getting_started/
 ##
 # influxURL: http://influxdb-influxdb.tick:8086
+
+## 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