Setup cachix binary cache

[hertrste]

Summary by CodeRabbit

• Chores
  • Improved automated testing by enabling an OpenStack Nix build cache to speed up CI runs.
  • Kept existing flake checks unchanged.
  • Added a new NixOS live migration test job that installs Nix, uses the same cache setup, and runs the live-migration test driver.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: b56e4f41-b37f-4d1b-a6a2-2330f103815f

📥 Commits

Reviewing files that changed from the base of the PR and between 6e26360 and 5c6e239.

📒 Files selected for processing (1)

• .github/workflows/qa.yml

📝 Walkthrough

Walkthrough

The NixOS QA workflow configures the openstack-nix Cachix cache for the basic test and a new live-migration test job using CACHIX_AUTH_TOKEN. The existing flake-check job remains unchanged.

Changes

CI cache configuration

Layer / File(s)	Summary
Configure Cachix for NixOS tests .github/workflows/qa.yml	The nixos-basic-test job and new nixos-live-migration-test job use cachix/cachix-action@v17 with the openstack-nix cache and authentication secret, with the latter running the live-migration test driver.

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

Suggested reviewers: pkr4711

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: adding Cachix binary cache usage to the workflow.
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
• Commit unit tests in branch cachix

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[coderabbitai]

Actionable comments posted: 1

🤖 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 @.github/workflows/qa.yml:
- Around line 17-20: Correct the indentation of the Cachix action step using the
`cachix-action@v17` entry: align `with:` beneath `uses:`, and nest `name` and
`authToken` beneath `with:` so the workflow parses as valid YAML.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: dc96758f-5fb3-4905-bfd2-babe7120b167

📥 Commits

Reviewing files that changed from the base of the PR and between cc607df and cff3fb1.

📒 Files selected for processing (1)

• .github/workflows/qa.yml

[coderabbitai]

Actionable comments posted: 2

🤖 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 @.github/workflows/qa.yml:
- Around line 12-20: Add explicit workflow-level permissions in
.github/workflows/qa.yml, granting only contents: read for the nixos-basic-test
and other jobs. Place the permissions declaration at the workflow level so all
jobs use least-privilege GITHUB_TOKEN access.
- Line 34: Update the actions/checkout@v6 step in the new job to disable
persisted checkout credentials by configuring its persist-credentials option as
false. Leave the existing checkout behavior and subsequent build/test steps
unchanged.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 5fb869e0-45e4-43b9-b350-efe47452c7a5

📥 Commits

Reviewing files that changed from the base of the PR and between cff3fb1 and 6e26360.

📒 Files selected for processing (1)

• .github/workflows/qa.yml