feat: Expose metrics-labels flag via Spark Operator Helm chart

[IgorSteps]

Purpose of this PR

Expose the Spark Operator's metrics-labels flag as a Helm chart value so users can add custom labels (for example using standard K8s labels) to the Spark Operator standard metrics. Right now, the chart hard codes that flag to app_type so the documented ability to add your own label keys is not actually possible by developers using your Helm chart.

This makes it much easier to build practical monitoring on whole platforms that use Spark Operator. Developers would be able to filter your standard metrics by e.g., namespace, app, component or team. They would have the ability to build common dashboards and setup targeted alerts without coming with elaborate ways to include enough information in the only available app_type label to achieve that instead.

Proposed changes:

• Adds prometheus.metrics.labels value to the values.yaml;
• Uses it in the deployment if specified, otherwise defaults to app_type for backwards compatibility;
• Helm chart automatic doc updates and unit test.

Change Category

• Bugfix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that could affect existing functionality)
• Documentation update

Rationale

This keeps the current app_type value as default but lets users define their own custom labels.

Checklist

• I have conducted a self-review of my own code.
• I have updated documentation accordingly.
• I have added tests that prove my changes are effective or that my feature works.
• Existing unit tests pass locally with my changes.

Additional Notes

None.

[ChenYi015]

/ok-to-test

[ChenYi015]

/approve

[ChenYi015]

@IgorSteps You need to sign off your commits to pass the DCO checks, see https://www.kubeflow.org/docs/about/contributing/#sign-off-your-commits.

[ChenYi015]

/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ChenYi015

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [ChenYi015]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment