fix: honor klog -stderrthreshold even when -logtostderr is true

[pierluigilenoci]

What changed

klog v2 defaults -logtostderr to true, which silently ignores -stderrthreshold — all log levels go to stderr unconditionally. This has been an open issue since 2020.

klog v2.140.0 introduced a fix behind an opt-in flag (legacy_stderr_threshold_behavior). This PR bumps klog to v2.140.0 and enables the fix in flags/flags.go so that -stderrthreshold is honored, while preserving the current default behavior (stderrthreshold=INFO means all logs still go to stderr unless the user explicitly overrides it on the command line).

What the fix does

klog.InitFlags(nil)
flag.Set("legacy_stderr_threshold_behavior", "false") // enable the klog fix
flag.Set("stderrthreshold", "INFO")                   // preserve current default

Since the Import() function applies caller-provided defaults after InitFlags, any project-level overrides via defmap continue to work as before.

References

• Upstream issue: stderrthreshold not honored when logtostderr is set kubernetes/klog#212
• Upstream fix: feat: fix stderrthreshold not honored when logtostderr is set (#212) + two new flags kubernetes/klog#432

[pierluigilenoci]

Hi, the kne-presubmit check is pending with "Needs /gcbrun from a collaborator". Could a maintainer please run /gcbrun when convenient? Thanks!

[pierluigilenoci]

Hi — gentle reminder. The kne-presubmit check is pending with "Needs /gcbrun from a collaborator." Could a maintainer please run /gcbrun when convenient? Thanks!

[pierluigilenoci]

Hi — friendly follow-up. Could a collaborator run /gcbrun to trigger the presubmit check? The code change is minimal (klog flag configuration) and all other checks pass. Thank you!

[pierluigilenoci]

Hi — gentle ping on this PR. The kne-presubmit (kne-external) check is still waiting on /gcbrun from a collaborator. Could someone run it when convenient? The code change is minimal (klog flag configuration). Thank you!

[pierluigilenoci]

Hi — just a quick ping on the CI status. The go / lint failure was due to a runner receiving a shutdown signal mid-run (not an actual lint error — golangci-lint never finished). The kne-presubmit (kne-external) check is waiting on /gcbrun from a collaborator.

Could a maintainer run /gcbrun to trigger the presubmit check? The change is minimal (klog flag initialization) and all other checks pass. Thank you!

[marcushines]

/gcbrun