Unable to create serviceMonitor from Helm chart with Kustomize

[stoupance]

Describe the bug

I'm trying to use Kustomize to inflate the Helm chart of ingress-nginx in order to add the serviceMonitor and prometheusRule sections, for monitoring purposes. It is disabled by default in the provided helmChart, but it can be overrided as a native chart values.
The YAML built by Kustomize outputs the prometheusRule section as expected but not the serviceMonitor one. I tried multiple configurations and nothing output any YAML configuration for serviceMonitor

To put aside any issue from Helm itself, it works perfectly with a vanilla Helm (output YAML for both serviceMonitor and prometheusRule) but not when using Kustomize ontop of Helm.

Files that can reproduce the issue

kustomization.yaml

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

helmCharts:
- name: ingress-nginx
  valuesInline:
    controller:
      metrics:
        enabled: true
        serviceMonitor:
          enabled: true
        prometheusRule:
          enabled: true
  version: 4.0.6
  repo: https://kubernetes.github.io/ingress-nginx
  releaseName: xxx

or

kustomization.yaml

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
metadata:
  name: ingress-nginx
generators:
  - generators.yaml

generators.yaml

apiVersion: builtin
kind: HelmChartInflationGenerator
metadata:
  name: nginx
name: ingress-nginx
repo: https://kubernetes.github.io/ingress-nginx
releaseName: xxx
valuesFile: values.yaml

value.yaml

controller:
  metrics:
    enabled: true
    serviceMonitor:
      enabled: true
    prometheusRule:
      enabled: true

Expected output

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: toto-ingress-nginx-controller
  labels:
    helm.sh/chart: ingress-nginx-4.0.6
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/instance: xxx
    app.kubernetes.io/version: "1.0.4"
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: controller
spec:
  endpoints:
    - port: metrics
      interval: 30s
  namespaceSelector:
    matchNames:
      - default
  selector:
    matchLabels:
      app.kubernetes.io/name: ingress-nginx
      app.kubernetes.io/instance: xxx
      app.kubernetes.io/component: controller

Actual output

The output doesn't have any serviceMonitor YAML section as expected but still contains the rest of the YAML manifests (Service, Deployment, ClusterRole...)

Kustomize version

{Version:kustomize/v4.4.0 GitCommit:63ec6bdb3d737a7c66901828c5743656c49b60e1 BuildDate:2021-09-27T16:24:12Z GoOs:linux GoArch:amd64}

Platform

Linux

Additional context

It doesn't work for both Kustomize configurations provided and it works when using only Helm. Sadly, there is no error and.
Any help will be greatly appreciated. Thanks!

[k8s-ci-robot]

@stoupance: This issue is currently awaiting triage.

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Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[stoupance]

Issue not related to Kustomize but how the helm chart was build. PR here -> kubernetes/ingress-nginx#7829