feat(chart): add opt-in PodDisruptionBudget for Longhorn UI - #13378

Please remember to update the chart README for the new configurable value podDisruptionBudget

Thanks, good catch. Pushed a fix using ne (toString ...) "" so maxUnavailable: 0 and minAvailable: 0 are now preserved.

I kept a three-branch form rather than dropping default 1 entirely: if both maxUnavailable and minAvailable are empty, it still falls back to minAvailable: 1 so the rendered PDB stays valid. Verified with helm template for maxUnavailable=0, minAvailable=0, both-empty (→ minAvailable: 1), and 50%; helm lint passes.

Rebased onto the latest master to clear the BEHIND state. The 0-value fix @COLDTURNIP requested is in — the PDB template uses ne (toString $pdb.maxUnavailable) "", so maxUnavailable: 0 / minAvailable: 0 render as-is while the empty-string default still falls back to minAvailable: 1 (verified via helm template). PTAL / could you resolve the thread when you get a chance? Thanks!

Hello @somaz94
Thanks for your contribution!
Since #12889 includes several areas, could you create an imporvement ticket in https://github.com/longhorn/longhorn/issues and link it to #12889? It will help manage and validate the improvement. Thanks.

Thanks @derekbit! I've opened a dedicated improvement ticket for this UI PDB slice and linked it to #12889:

• [IMPROVEMENT] Add opt-in PodDisruptionBudget for the Longhorn UI Deployment #13466 — [IMPROVEMENT] Add opt-in PodDisruptionBudget for the Longhorn UI Deployment

This PR (#13378) implements that ticket. Happy to adjust the scope or split further if that helps validation/backport. PTAL 🙏

@somaz94 Could you check if the comments from copilot need to be addressed? Thanks.

@derekbit Thanks for the ping — both Copilot comments are addressed in 23518fe:

1. Single-replica PDB gating — the template now renders only when podDisruptionBudget.enabled and longhornUI.replicas > 1, matching the documented "effective only when replicas > 1" behavior. This avoids creating an always-blocking PDB (minAvailable: 1) that could stall node drains on single-replica setups.
2. minAvailable type — documented as string (IntOrString) via a helm-docs (string) annotation, so percentage values like "50%" are correctly reflected (consistent with maxUnavailable).

Verified with helm template: replicas=2 renders the PDB, replicas=1 renders nothing, and maxUnavailable: 0 is still preserved. helm lint is clean.

@COLDTURNIP @derekbit — I believe everything raised is now addressed; summarizing so the stale review can be re-checked:

• Preserve valid zero values (@COLDTURNIP): fixed in 2c6085c. The template uses {{ if ne (toString $pdb.maxUnavailable) "" }} … {{ else if ne (toString $pdb.minAvailable) "" }} … {{ else }} minAvailable: 1 {{ end }}, so 0 is preserved. Verified: minAvailable: 0 renders minAvailable: 0 and maxUnavailable: 0 renders maxUnavailable: 0 (neither collapses to the minAvailable: 1 default).
• Copilot — gate on replicas > 1: done in 8499f5a; the PDB template only renders when (gt (int .Values.longhornUI.replicas) 1), matching the documented "effective only when replicas > 1" behavior.
• Copilot — minAvailable type: the README/values now document it as string (IntOrString), so percentages like "50%" are clearly supported.
• Improvement ticket (@derekbit): opened [IMPROVEMENT] Add opt-in PodDisruptionBudget for the Longhorn UI Deployment #13466 and linked it to [IMPROVEMENT] Improve Longhorn Helm chart defaults and security/availability configurability #12889.

No functional changes outstanding on my side — @COLDTURNIP could you take another look when you have a moment? Thanks!

LGTM.

Nit: I suggest cleaning up the commit history by folding fixups into the appropriate commits or squashing them before the merge.

Hello @somaz94 Could you address the comment? Thank you.

Thanks @c3y1huang @derekbit — done. The four commits are now folded into a single commit (7466f58), rebased onto the latest master (this also clears the out-of-date branch state). The net change is unchanged: 3 files, 33 insertions.

Re-verified after the squash with helm lint (0 failed) and helm template:

• default values → no PDB rendered
• enabled=true → minAvailable: 1
• replicas=1 → no PDB rendered (the replicas > 1 gate)
• maxUnavailable set → minAvailable omitted (mutually exclusive)
• minAvailable=0 → preserved as 0

@COLDTURNIP the points from your review are addressed in this commit — could you take another look when you get a chance? The CHANGES_REQUESTED from 06-23 predates the fixes and is still blocking the merge.

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