feat: add target group info metric

[msvticket]

Description

When monitoring target groups by importing cloudwatch metrics it's tricky to see what service an alert corresponds to. This PR adds a relation metric called aws_target_group_info that you can use to enrich the metric from cloudwatch with labels for service and namespace.

Example PromQL:

aws_target_group_info * on(target_group) group_left last_over_time(aws_applicationelb_healthy_host_count_minimum[20m])

Checklist

• [ ] Added tests that cover your change (if possible)
• [ ] Added/modified documentation as required (such as the README.md, or the docs directory)
• [x] Manually tested
• [x] Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! :exploding_head:

• [ ] Backfilled missing tests for code in same general area :tada:
• [ ] Refactored something and made the world a better place :star2:

[k8s-ci-robot]

Hi @msvticket. Thanks for your PR.

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: msvticket Once this PR has been reviewed and has the lgtm label, please assign johngmyers for approval. For more information see the Kubernetes Code Review Process.

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[oliviassss]

/ok-to-test

[msvticket]

Could you please review as well @oliviassss ?

[oliviassss]

@msvticket, sorry for the delay, and thanks for the contribution to improve the observability for LBC! I left some nit comments. Also, can you please adding the unit test coverage for pkg/aws/metrics/target_group.go?

[oliviassss]

want some second opnions from @M00nF1sh /assign @M00nF1sh

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: msvticket Once this PR has been reviewed and has the lgtm label, please ask for approval from m00nf1sh. For more information see the Kubernetes Code Review Process.

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Needs approval from an approver in each of these files:

• OWNERS

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/lifecycle stale

[msvticket]

/remove-lifecycle stale

[k8s-ci-robot]

PR needs rebase.

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