Feature flagging for exporting of Kanister prometheus metrics (#2235)

* Added new metrics.enabled flag to helm chart

* Added new environment variable to capture the metrics.enabled flag from helm chart values.yaml

* Addressed Pavan's review comments

helm/kanister-operator/templates/deployment.yaml

@@ -41,6 +41,8 @@ spec:
           value: {{ .Values.controller.logLevel }}
         - name: DATA_STORE_PARALLEL_UPLOAD
           value: {{ .Values.controller.parallelism | quote }}
+        - name: KANISTER_METRICS_ENABLED
+          value: {{ .Values.controller.metrics.enabled | quote }}
 {{- if .Values.resources }}
         resources:
 {{ toYaml .Values.resources | indent 12 }}

helm/kanister-operator/values.yaml

@@ -28,6 +28,11 @@ controller:
   # true : CRDs would be created by kanister controller
   updateCRDs: true
   parallelism: 8
+  metrics:
+    # metrics.enabled specified if the kanister-prometheus framework has been enabled
+    # false : kanister-prometheus framework has been disabled
+    # true: kanister-prometheus framework has been enabled
+    enabled: false
 bpValidatingWebhook:
   enabled: true
   tls: