Add node image RPM diff to release info API response

[stbenjam]

Summary

• Adds nodeImageRpmDiff field to the APIReleaseInfo struct, exposing the RPM package diff between previous and current node images in the JSON API response
• The RPM diff is fetched concurrently alongside the existing changelog generation, so it adds no additional latency
• This data was previously only available on the HTML page but missing from the API

🤖 Generated with Claude Code

Testing locally works for me:

  "nodeImageRpmDiff": {
    "changed": {
      "kernel": {
        "old": "6.12.0-211.5.1.el10_2",
        "new": "6.12.0-211.6.1.el10_2"
      },
      "kernel-core": {
        "old": "6.12.0-211.5.1.el10_2",
        "new": "6.12.0-211.6.1.el10_2"
      },
      "kernel-modules": {
        "old": "6.12.0-211.5.1.el10_2",
        "new": "6.12.0-211.6.1.el10_2"
      },
      "kernel-modules-core": {
        "old": "6.12.0-211.5.1.el10_2",
        "new": "6.12.0-211.6.1.el10_2"
      },
      "kernel-modules-extra": {
        "old": "6.12.0-211.5.1.el10_2",
        "new": "6.12.0-211.6.1.el10_2"
      }
    }
  }

From http://localhost:8080/api/v1/releasestream/4.22.0-0.nightly/release/4.22.0-0.nightly-2026-03-30-221541?from=4.22.0-0.nightly-2026-03-30-132356

Summary by CodeRabbit

Release Notes

New Features

• Release information now includes RPM package differences between node image versions, providing detailed package-level insights into version changes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 0d806838-8394-4f9a-bfc2-3e82f411a497

📥 Commits

Reviewing files that changed from the base of the PR and between 6dda498 and bb361e8.

📒 Files selected for processing (2)

• cmd/release-controller-api/http.go
• pkg/release-controller/types.go

---

📝 Walkthrough

Walkthrough

The changes extend the APIReleaseInfo struct with a new optional NodeImageRpmDiff field and add logic to compute it concurrently while rendering changelog data. When both previous and current public pull specs are available, an RPM diff is retrieved via an existing method and included in the API release response payload.

Changes

Cohort / File(s)	Summary
APIReleaseInfo Struct Extension pkg/release-controller/types.go	Added optional NodeImageRpmDiff *RpmDiff field to APIReleaseInfo struct with JSON tag nodeImageRpmDiff,omitempty.
RPM Diff Computation and Population cmd/release-controller-api/http.go	Integrated concurrent RPM diff retrieval into apiReleaseInfo function; calls c.releaseInfo.RpmDiff() when previous and current pull specs exist, with errors logged at verbosity level 4 and otherwise ignored; result populated into NodeImageRpmDiff field.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A diff of RPMs, concurrent and swift,
Fields added with grace, a structured gift,
Errors handled kindly, results on display,
The API now richer in every way! 🚀

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: adding a node image RPM diff field to the release info API response, which is reflected in both the struct addition and the API payload changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch discrepencies

---

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[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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

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[openshift-ci]

@stbenjam: all tests passed!

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