---
apiVersion: helm.cattle.io/v1
kind: HelmChart
metadata:
  name: prometheus-exporter-postgresql
  namespace: kube-system
spec:
  repo: https://prometheus-community.github.io/helm-charts
  chart: prometheus-postgres-exporter
  targetNamespace: monitoring
  valuesContent: |-
    config:
      datasourceSecret:
        name: prometheus-exporter-postgresql
        key: connection-string
...