feat(helm chart): add optional ServiceMonitor for lvmNode service

[moss-telavox]

Option to deploy a servicemonitor (prometheus operator) to automatically scrape the lvmNode metrics.

Pull Request template

Please, go through these steps before you submit a PR.

Why is this PR required? What issue does it fix?:

It allows for creating a Prometheus Operator ServiceMonitor to scrape the lvmNode metrics.
Right now one has to create one outside manually.

What this PR does?:
It allows for creating a Prometheus Operator ServiceMonitor to scrape the lvmNode metrics.

By setting lvmNode.serviceMonitor.enabled to true and specifying whatever label ones PrometheusOperator looks for (common is to have release: promtetheus)

Does this PR require any upgrade changes?:
No (at least I don't think so)

If the changes in this PR are manually verified, list down the scenarios covered::

helm template . | grep ServiceMonitor
will not render anything by default

Setting lvmNode.serviceMonitor.enabled=true" will render the template.
helm template . --set lvmNode.serviceMonitor.enabled=true | grep ServiceMonitor

Any additional information for your reviewer? :
Mention if this PR is part of any design or a continuation of previous PRs

Checklist:

• Fixes #
• PR Title follows the convention of <type>(<scope>): <subject>
• Has the change log section been updated?
• Commit has unit tests
• Commit has integration tests
• (Optional) Are upgrade changes included in this PR? If not, mention the issue/PR to track:
• (Optional) If documentation changes are required, which issue on https://github.com/openebs/openebs-docs is used to track them:

[tiagolobocastro]

Looks like some error with your commit signature @moss-telavox, could you please take a look?

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✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.72%. Comparing base (8feeaa0) to head (b7490a6).
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Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #411      +/-   ##
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- Coverage    98.66%   97.72%   -0.94%     
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  Files            2        2              
  Lines          673     1055     +382     
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+ Hits           664     1031     +367     
- Misses           5       17      +12     
- Partials         4        7       +3     

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[moss-telavox]

@tiagolobocastro think I got it now. Sorry if it resulted in a bunch of CI mails for you guys.
It kept complaining about my name not being a valid email address.
In the end, had to modify the commit with --author="name <email>" in order for the DCO to pass.
So not just the Signed-off-by:

[abhilashshetty04]

Hi @moss-telavox ,

You do not need to create service monitor for localpv-lvm manually. chart present in openebs/monitoring (https://openebs.github.io/monitoring/) does create service monitor.

That chart deploys all monitoring related services for OpenEBS engines (mayastor, localpv-lvm, localpv-zfs).

[moss-telavox]

Hi @moss-telavox ,

You do not need to create service monitor for localpv-lvm manually. chart present in openebs/monitoring (https://openebs.github.io/monitoring/) does create service monitor.

That chart deploys all monitoring related services for OpenEBS engines (mayastor, localpv-lvm, localpv-zfs).

Ah! Thanks for pointing it out. Will give it a try!
Lets close this one!

[tiagolobocastro]

hmm though not everyone might use the monitoring chart
I think we should allow enabling from here

[dsharma-dc]

linting failures are there in CI runs.
Are we still considering this?

[moss-telavox]

I removed the trailing whitespace in values.yaml.