Honor stderrthreshold when logtostderr is enabled

[pierluigilenoci]

What this PR does

Fixes the -stderrthreshold flag so it is honored even when -logtostderr=true (the klog v2 default) in the triage/summarize tool.

Problem

klog v2 defaults -logtostderr to true. When this flag is active, the -stderrthreshold flag is silently ignored — all log messages (INFO, WARNING, ERROR, FATAL) are unconditionally written to stderr.

This has been an open issue since 2020: kubernetes/klog#212.

Fix

PR kubernetes/klog#432 introduced the fix in klog v2.140.0. This PR:

1. Bumps klog from v2.10.0 to v2.140.0 in triage/go.mod
2. Opts into the fixed behavior by setting legacy_stderr_threshold_behavior=false and stderrthreshold=INFO on the klogFlags FlagSet in setUpLogging()

Setting stderrthreshold=INFO preserves the current default behavior. Users can now override it on the command line and it will actually work.

Changes

• triage/summarize/summarize.go: Add klogFlags.Set() calls after klog.InitFlags(klogFlags)
• triage/go.mod / triage/go.sum: Bump k8s.io/klog/v2 v2.10.0 → v2.140.0

Ref: kubernetes/klog#212, kubernetes/klog#432

[pierluigilenoci]

Hi @BenTheElder, @krzyzacy, @fejta — would you be willing to review? Thank you!

[BenTheElder]

Hey, @krzyzacy is emeritus these days, the CI will auto-assign current reviewers and auto-suggest a current approver for assigning after review.

[BenTheElder]

this seems ok but I don't think we're using any of this

[pierluigilenoci]

You're right — if triage/summarize isn't actively used, this has no practical impact. I already applied your URL nit in the previous push. Happy to close this if the code is effectively dead. What do you think?

[BenTheElder]

nit can we use:

Suggested change

	// Opt into fixed stderrthreshold behavior (kubernetes/klog#212).
	// Opt into fixed stderrthreshold behavior (https://github.com/kubernetes/klog/issues/212).

It's not much longer but you can probably click it in your editor or at least copy-paste to the browser more easily, and it will not generate backreference noise on the issue.

[pierluigilenoci]

Hi @aojea, @upodroid — this PR adds one line to set legacy_stderr_threshold_behavior=false after klog.InitFlags(), per the upstream fix in kubernetes/klog#432. This ensures klog properly respects the stderrthreshold flag.

Would you be able to review when you get a chance? Thank you!

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[pierluigilenoci]

Hi @BenTheElder — thanks for the feedback. I applied your URL nit suggestion in the latest push. Regarding your comment about the code not being actively used: would you still like this fix applied for correctness (in case the code is exercised in the future), or would you prefer to close this PR? Happy either way — just let me know. Thank you!

[pierluigilenoci]

Hi @BenTheElder — just a friendly follow-up on the open question.

Looking at the codebase, triage/summarize does appear to be actively used:

• triage/main.go imports and calls summarize.Main() directly
• The Dockerfile builds the triage binary and deploys it as a container image (gcr.io/.../triage:latest)
• triage/summarize/ had commits as recently as Dec 2025 (by @dims), and the broader triage/ directory was updated in Apr 2026

So the setUpLogging code path in summarize.go is exercised whenever the triage tool runs.

The change itself is small — it opts into the fixed stderrthreshold behavior introduced in klog v2.140.0 (kubernetes/klog#432) and sets stderrthreshold=INFO to preserve backward compatibility.

Would you be willing to take another look? Thank you!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: krzyzacy, pierluigilenoci
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