butane/util: use yaml instead of json for unmarhal

[angelcerveraroldan]

Since yaml is a superset of json, we can use the yaml unmarshal function instead of the json one.

This unmarshalling will be more accurate, as it does not convert numbers to floats (which would lead to awkward formatting of the generated MCO)

Adding test and release note is still needed

closes: #2309

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• butane/config/util/util.go

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GitHub Actions: Release notes / 0_Require release note.txt: butane/util: use yaml instead of json for unmarhal

Conclusion: failure

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---

GitHub Actions: Release notes / Require release note: butane/util: use yaml instead of json for unmarhal

Conclusion: failure

View job details

##[group]Run set -euo pipefail
 �[36;1mset -euo pipefail�[0m
 �[36;1mif [ -n "skip-notes" ]; then�[0m
 �[36;1m    # Don't trust the label list in the event metadata, since runs�[0m
 �[36;1m    # can be scheduled out of order and the list might be stale.�[0m
 �[36;1m    label=$(curl --no-progress-meter \�[0m
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 ##[error]Process completed with exit code 1.

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- **Naming**: PascalCase exported, camelCase unexported, snake_case filenames

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Files:

• butane/config/util/util.go

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📄 CodeRabbit inference engine (AGENTS.md)

Files:

• butane/config/util/util.go

🔇 Additional comments (1)

butane/config/util/util.go (1)

159-159: LGTM!

---

📝 Walkthrough

Walkthrough

TranslateBytesYAML now uses the YAML decoder to parse intermediate JSON before converting the configuration to YAML. This prevents large numeric values from being emitted in scientific notation for OpenShift MachineConfigs.

Changes

YAML translation

Layer / File(s)	Summary
Intermediate configuration decoding butane/config/util/util.go	TranslateBytesYAML uses yaml.Unmarshal instead of json.Unmarshal before YAML re-encoding.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Merge Risk: ⚪ Minimal · up to f7289

This localized change switches YAML unmarshalling to preserve numeric values more accurately; no actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: prestist

🚥 Pre-merge checks | ✅ 5 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The change addresses issue #2309 by replacing JSON unmarshalling with YAML unmarshalling to preserve large integer MiB values and prevent scientific notation in generated MachineConfigs.
Out of Scope Changes check	✅ Passed	The pull request changes one relevant unmarshalling call and contains no unrelated code changes.
Commit Message Convention	✅ Passed	PASS. The PR contains one non-merge commit. Its subject is butane/util: use yaml instead of json for unmarhal: it has a subsystem, the description starts with lowercase use, uses imperative mood, …
Title check	✅ Passed	The title describes the YAML-for-JSON unmarshalling change, uses the required subsystem prefix, uses lowercase wording after the colon, and uses imperative mood. The description contains a typo in “un…
Description check	✅ Passed	The description directly explains the YAML unmarshalling change, its effect on numeric formatting, and the remaining test and release note work.

Full details: Commit Message Convention

Explanation

PASS. The PR contains one non-merge commit. Its subject is butane/util: use yaml instead of json for unmarhal: it has a subsystem, the description starts with lowercase use, uses imperative mood, and has no trailing period. The commit is the only commit in the PR range.

Full details: Title check

Explanation

The title describes the YAML-for-JSON unmarshalling change, uses the required subsystem prefix, uses lowercase wording after the colon, and uses imperative mood. The description contains a typo in “unmarhal,” but remains clear.

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Binary size report (bin/amd64/ignition)

	Size
Base (main)	33MiB
PR (#2310)	33MiB
Delta	-60KiB (-0.18%)

[angelcerveraroldan]

Seems like the issue was coming from how we handle MCO.

We first generate the igntion json from the butane yaml, then we unmarshal said json, and re-marshal it in yaml.

In the step where we are unmarshal'ing the json igntion config, we lose the type information, and float64 is chosen by default for all numbers, which are later formatted with scientific notation.

It seems that the reason we have to do this whole back and forth is due to missing functionality in the yaml library we use - which has been deprecated for about a year an a half now. I wonder if its worth looking into using an alternative yaml library that's maintained. @prestist wdyt