docs: docs for machine id metrics and hw-health metrics fetch

[yoks]

Documentation updates for #2433 and #2168

Related issues

#2433 #2168

Type of Change

• Add - New feature or capability
• Change - Changes in existing functionality
• Fix - Bug fixes
• Remove - Removed features or deprecated functionality
• Internal - Internal changes (refactoring, tests, docs, etc.)

Breaking Changes

• This PR contains breaking changes

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• No testing required (docs, internal refactor, etc.)

Additional Notes

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Reviewing files that changed from the base of the PR and between 08c2431 and 0937c8f.

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• docs/operations/monitoring-health.md

✅ Files skipped from review due to trivial changes (1)

• docs/operations/monitoring-health.md

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Summary by CodeRabbit

• Documentation
  • Expanded monitoring guidance with a dedicated “Hardware Entity Metrics” section covering Redfish *Metrics-backed scalar collection, Prometheus naming/labels, OTLP parity, and that metrics emit only after the first discovery pass.
  • Documented new configuration defaults for entity discovery cadence/concurrency and the metrics collector polling interval/concurrency.
  • Added an opt-in “Per-Object Health Metrics” section describing classifications, labeling (including in_use for machines), enablement, and metric disappearance behavior when objects become healthy or lose classification.

Walkthrough

Expanded monitoring documentation with hardware entity metrics configuration and output details, plus opt-in per-object health metrics behavior and lifecycle semantics.

Changes

Monitoring health documentation

Layer / File(s)	Summary
Hardware entity metrics documentation docs/operations/monitoring-health.md	Adds entity discovery and collector defaults, Redfish *Metrics collection behavior, configuration, Prometheus naming and labels, OTLP correspondence, and first-discovery requirements.
Per-object health metrics documentation docs/operations/monitoring-health.md	Documents classification-based unhealthy-object metrics, configuration, labels, default behavior, and series disappearance.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is related to the docs update, though it is narrower and less precise than the actual hardware entity and per-object health metrics changes.
Description check	✅ Passed	The description matches the documentation-only scope and references the related pull requests and internal change type.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

🔍 Container Scan Summary

No Grype artifacts were found to aggregate.

[github-actions]

🌿 Preview your docs: https://nvidia-preview-pull-request-3377.docs.buildwithfern.com/infra-controller

[coderabbitai]

Actionable comments posted: 4

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docs/operations/monitoring-health.md`:
- Around line 595-597: The monitoring documentation inaccurately claims
classification-based emission keeps cardinality bounded. In the opt-in emission
description, replace “bounded” with wording that it helps contain cardinality,
clarify that object_id still scales series with fleet size, and note that
multiple enabled classifications multiply per-object series.
- Around line 610-617: The rack alert example is incompatible with the
documented metric labels because it neither filters to machines nor identifies
racks. Update the example prose and PromQL to describe a fleet-wide
hardware-unhealthy machine count, or add/document a `rack_id` label and group
the query by rack so it can correctly alert on per-rack totals.
- Around line 227-232: Clarify the sink-specific query contract in the section
describing series labels and OTLP. State that Prometheus exposes inventory
context as metric labels, while OTLP exports it as resource attributes; document
the exact attribute-to-label mapping and query differences, or limit the claim
to shared metric names without asserting identical Grafana queries.
- Around line 604-608: The monitoring documentation’s eviction timing statement
is inaccurate: update the paragraph near the per-object classification metrics
to state that series are retained for the registry’s hold period, which is
configured slightly longer than the state controllers’ `metric_hold_time`,
rather than expiring exactly at that value. Preserve the existing behavior for
empty classifications and aggregate metrics.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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📥 Commits

Reviewing files that changed from the base of the PR and between 1a1b1e2 and 08c2431.

📒 Files selected for processing (1)

• docs/operations/monitoring-health.md