ServiceMonitor metricRelabelings not correctly templated

[dhhuynh2]

Describe the bug

When setting metricRelabelings, helm will fail when installing the chart with the following error:

  Error: YAML parse error on jenkins/templates/jenkins-controller-servicemonitor.yaml: error converting YAML to JSON: yaml: line 19: did not find expected ',' or ']'

Version of Helm and Kubernetes

- Helm: v3.8.0
- Kubernetes: v1.20.15

Chart version

4.2.15

What happened?

1. Set values.json as such below (example):

...
controller:
  ...
  prometheus:
    enabled: true
    ...
    metricRelabelings:
      - sourceLabels: [__name__]
        regex: "some_regex_(.*)"
        targetLabel: "someLabel"
      - sourceLabels: [__name__]
        regex: "another_regex(.*)"
        targetLabel: "anotherLabel"

2. Installed the chart.

3. Received:

Error: YAML parse error on jenkins/templates/jenkins-controller-servicemonitor.yaml: error converting YAML to JSON: yaml: line 19: did not find expected ',' or ']'

What you expected to happen?

Chart should be correctly installed without YAML validation errors.

How to reproduce it

Reproduced by locally templating jenkins/templates/jenkins-controller-servicemonitor.yaml file with my values.json values.

Anything else we need to know?

After digging into the template, I see this is where it's being set:

helm-charts/charts/jenkins/templates/jenkins-controller-servicemonitor.yaml

Line 30 in 2bbd9f0

metricRelabelings: {{ .Values.controller.prometheus.metricRelabelings }}

Since metricRelabelings is a list of maps, I believe this should be invoking toYaml as such:

{{- toYaml .Values.controller.prometheus.metricRelabelings | trim | nindent 6 }}

I've noticed an open PR that should resolve this in #638 if merged.