fix: honor klog -stderrthreshold even when -logtostderr is true#164
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johnjeffers merged 2 commits intoApr 24, 2026
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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 (kubernetes/klog#212). klog v2.140.0 introduced a fix behind an opt-in flag (legacy_stderr_threshold_behavior). This commit enables the fix so that -stderrthreshold is honored, while preserving the current default behavior (stderrthreshold=INFO means all logs still go to stderr unless the user overrides it on the command line). Ref: kubernetes/klog#212 Ref: kubernetes/klog#432 Signed-off-by: Pierluigi Lenoci <pierluigilenoci@gmail.com>
johnjeffers
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Apr 24, 2026
| klogFlags.Set("legacy_stderr_threshold_behavior", "false") | ||
| klogFlags.Set("stderrthreshold", "INFO") | ||
| klogFlags.Set("logtostderr", "true") | ||
| klogFlags.Set("stderrthreshold", "0") |
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Should probably remove either this line or line 75, since they appear to do the same thing.
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Good catch — the "INFO" form on line 75 and the numeric "0" on line 77 resolve to the same klog severity, so the second set was a leftover from the original code that I forgot to remove when I added the named constant. Removed the duplicate in 4a18301.
The "INFO" string form (line 75) and the numeric "0" form were both setting the same klog severity level. Keep the human-readable "INFO" that sits next to the explanatory comment and drop the redundant "0". Signed-off-by: Pierluigi Lenoci <pierluigi.lenoci@gmail.com> Signed-off-by: Pierluigi Lenoci <pierluigilenoci@gmail.com>
johnjeffers
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Apr 24, 2026
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@pierluigilenoci thank you for the contribution! This will go out in v1.6.2, likely later today, possibly tomorrow. |
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What changed
klog v2 defaults
-logtostderrtotrue, which silently ignores-stderrthreshold— all log levels go to stderr unconditionally. This has been an open issue since 2020.klog v2.140.0 (already in use by this project) introduced a fix behind an opt-in flag (
legacy_stderr_threshold_behavior). This PR enables the fix inbackend/internal/errorcapture/error_capture.goso that thestderrthresholdsetting is actually honored when-logtostderr=true.What the fix does
The fix is backward-compatible and preserves the current stderr capture behavior.
References