feat(helm) add namespaceOverride

[TheRealNoob]

What this PR does / why we need it:
adds support for namespaceOverride in values file, useful if this chart is subcharted. For example, many people include myself probably subchart this as part of their "standard monitoring deployment" and want to direct metrics-server off to namespace=kube-system.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
none

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[k8s-ci-robot]

Hi @TheRealNoob. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[rexagod]

/ok-to-test

[k8s-ci-robot]

@TheRealNoob: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-metrics-server-test-e2e-ha	8c98d9f	link	false	/test pull-metrics-server-test-e2e-ha

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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-sigs/prow repository. I understand the commands that are listed here.

[TheRealNoob]

so i see that one test failed, but i'm scratching my head wondering how that could be caused by my change here.....any pointers would be much appreciated

[stevehipwell]

@TheRealNoob I'm not sure we want to go down this avenue, but I'm open to being convinced. My main concern is that Helm doesn't have sub-charts, it has dependencies but these charts are just flattened to create a single "chart". Could you please explain what benefit you get from this pattern and why it's worth the implicit downsides? It seems to me that you're attempting to solve an issue in the layers above the chart by modifying the chart causing a leaking abstraction.

[TheRealNoob]

One of the most popular use-cases for namespaceOverride is creating an umbrella chart and then selectively changing the namespace for specific subcharts. For example, creating a chart that rolls together all of your monitoring tools into one release. You would probably pull together kube-prometheus-stack, prometheus-operator-admission-webhook, prometheus-operator-crds, metrics-server, another example exporter, etc. helm install monitoring-stack umbrella/chart -n monitoring would force all of these subcharts to that namespace, but metrics-server typically goes to namespace=kube-system, which could be overridden with this PR.

I can understand your hesitation to think I'm setting up some unique scenario but it is quite common

• prometheus-community/kube-prometheus-stack
• prometheus-community/kube-state-metrics
• basically every chart in prometheus-community
• grafana/grafana
• grafana/loki (recently added)
• dex/dex
• argoproj/argo-helm

I see metrics-server as a staple of every monitoring stack, so I'm a bit surprised this hasn't been added before now to be honest