docs(self-managed): correct Cassandra upgrade guidance

[sbaum1994]

TL;DR

Correct the 0.6.0 to 0.6.1 Cassandra upgrade guide so operators avoid unsafe sync and password changes, rely on the controller rollout, and use accurate verification steps.

Additional Details (optional for docs, build, test, refactor, ci, chore, style, and revert PRs)

Why

The upgrade guide can lead operators into a failed unscoped Helmfile sync, manual pod deletion that conflicts with the StatefulSet controller, and a health check that misses unready containers. It also names a keyspace that is not part of the 0.6.1 release.

What changed

• Warn operators not to run an unscoped 0.6.1 sync before completing the selected Cassandra migration, and document recovery from a failed sync.
• Warn operators to preserve Cassandra and OpenBao passwords during the migration and stop relying on the old Cassandra Secret.
• Make keyspace and migration-state verification inventory-driven instead of naming a later-release keyspace.
• Tell operators to monitor the automatic OrderedReady rollout instead of deleting additional pods.
• Check both pod status and ready-container counts during final verification.

Customer Release Notes

Corrects the self-managed 0.6.0 to 0.6.1 Cassandra upgrade procedure.

Plan Summary

Not applicable. Documentation only.

Usage

Follow the warnings and verification commands in the updated upgrade guide.

Notes

The full docs check reports one advisory docs-version-sync path warning that is also present on the clean baseline. Fern reports 0 errors.

References

• Move the Cassandra stack off Bitnami to official Apache Cassandra #317

Related Pull Requests

None.

Dependencies

None.

For the Reviewer

Review the warning placement, failed-sync recovery sequence, automatic rollout guidance, and readiness-aware pod filter.

For QA (optional for docs, build, test, refactor, ci, chore, style, and revert PRs)

• ./tools/ci/check-docs: Fern reports 0 errors and 1 baseline advisory warning.
• Tested the readiness filter with healthy, unready, initializing, pending, and completed pod rows. It reports only the unready and non-running rows.
• QA is not needed for this documentation-only change.

Issues

Relates to #317

Checklist

• I am familiar with the Contributing Guidelines.
• I have signed off my commits for Developer Certificate of Origin (DCO) compliance.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

Summary by CodeRabbit

• Documentation
  • Expanded the 0.6.0–0.6.1 upgrade guide with clearer Cassandra migration warnings and verification steps.
  • Added guidance to preserve existing Cassandra credentials during migration.
  • Clarified datacenter expansion and in-place volume adoption procedures.
  • Improved rollout monitoring and control-plane health checks to help identify incomplete or unhealthy migrations.

[coderabbitai]

📝 Walkthrough

Walkthrough

The 0.6.0→0.6.1 upgrade guide adds safeguards for scoped deployment and credential preservation, generalizes Cassandra migration checks, updates StatefulSet rollout instructions, and strengthens control-plane health verification.

Changes

Upgrade guidance

Layer / File(s)	Summary
Migration safeguards docs/user/release-notes/0.6.0-to-0.6.1-upgrade.md	Adds warnings about completing Cassandra migration steps before an unscoped sync and preserving existing Cassandra credentials.
Cassandra migration procedures docs/user/release-notes/0.6.0-to-0.6.1-upgrade.md	Generalizes replication updates to applicable keyspaces and requires checking migration state for every returned migration table.
StatefulSet and verification docs/user/release-notes/0.6.0-to-0.6.1-upgrade.md	Replaces manual pod recreation guidance with StatefulSet rollout monitoring and uses an awk readiness check for migration verification.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Suggested reviewers: apartha-nv

🚥 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 follows Conventional Commits and accurately describes this documentation-only Cassandra upgrade guide update.
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 docs/fix-061-upgrade-warnings

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[github-actions]

🌿 Preview your docs: https://nvidia-preview-docs-fix-061-upgrade-warnings.docs.buildwithfern.com/nvcf

[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 `@docs/user/release-notes/0.6.0-to-0.6.1-upgrade.md`:
- Around line 370-381: Clarify in the StatefulSet rollout instructions that
cassandra-0 is recreated first because the preceding command explicitly deletes
it; state that normal StatefulSet rollouts proceed from the highest ordinal
downward, so the controller is not inherently starting at ordinal 0.

🪄 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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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: ba278d70-9e82-4f3d-8069-bfae6921fc7e

📥 Commits

Reviewing files that changed from the base of the PR and between 6a8ed21 and f9a4177.

📒 Files selected for processing (1)

• docs/user/release-notes/0.6.0-to-0.6.1-upgrade.md