Honor stderrthreshold when logtostderr is enabled

[pierluigilenoci]

Summary

Opt into the new klog behavior so that -stderrthreshold is honored even when -logtostderr=true (the default). Set stderrthreshold=INFO to preserve backward compatibility.

Background

When -logtostderr=true, -stderrthreshold was ignored -- all logs went to stderr. Fixed in kubernetes/klog#432 (v2.140.0+), but projects must opt in.

Changes

• Added flag.Set("legacy_stderr_threshold_behavior", "false") and flag.Set("stderrthreshold", "INFO") after klog.InitFlags() in cmd/mpi-operator/main.go
• Bumped k8s.io/klog/v2 from v2.130.1 to v2.140.0

References

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

[pierluigilenoci]

Hi @tenzen-y, @terrytangyuan, @alculquicondor -- would you be willing to review? Thank you!

[tenzen-y]

Hi @tenzen-y, @terrytangyuan, @alculquicondor -- would you be willing to review? Thank you!

@pierluigilenoci Thank you for opening this PR, the changes look great!
But, we have to update Go version to 1.26 to address CI problem in a separate PR in advance.

mkdir -p /home/runner/work/mpi-operator/mpi-operator/go/src/github.com/kubeflow/mpi-operator/bin
go: downloading sigs.k8s.io/controller-runtime/tools/setup-envtest v0.0.0-20260402120904-17460276e0da
go: downloading sigs.k8s.io/controller-runtime v0.23.3
go: sigs.k8s.io/controller-runtime/tools/setup-envtest@latest: sigs.k8s.io/controller-runtime/tools/setup-envtest@v0.0.0-20260402120904-17460276e0da requires go >= 1.26.0 (running go 1.25.0; GOTOOLCHAIN=local)
make: *** [Makefile:160: bin/envtest] Error 1
Error: Process completed with exit code 2.

Could you open a PR to update the Go version separately in advance?
Thank you.

[tenzen-y]

Could you move flags to https://github.com/kubeflow/mpi-operator/blob/a1081f0acb92c8e117763ebaf6d71bd1db87fba3/cmd/mpi-operator/app/options/options.go?

[pierluigilenoci]

Hi @tenzen-y — thank you for the review and the positive feedback! Two items to address: (1) Move flags to options.go — will move the flag.CommandLine.Set calls into cmd/mpi-operator/app/options/options.go as requested. (2) Go 1.26 update — understood, the Validate CI failure is because controller-runtime/tools/setup-envtest now requires Go >= 1.26.0. I will open a separate PR to bump the Go version first, then rebase this one on top. Will update shortly. Thank you!

[pierluigilenoci]

Hi @tenzen-y — thank you for the review feedback! I saw the note about updating the Go version.

Just to confirm: the Validate CI failure (setup-envtest requires go >= 1.26.0, running go 1.25.0) is a repo-wide issue — it also fails on PR #795 with the same error. This is not caused by changes in this PR.

I'm happy to address the Go version update as part of this PR or in a separate one — whichever you prefer. Could you let me know how you'd like to proceed? Thank you!

[tenzen-y]

Hi @tenzen-y — thank you for the review feedback! I saw the note about updating the Go version.

Just to confirm: the Validate CI failure (setup-envtest requires go >= 1.26.0, running go 1.25.0) is a repo-wide issue — it also fails on PR #795 with the same error. This is not caused by changes in this PR.

I'm happy to address the Go version update as part of this PR or in a separate one — whichever you prefer. Could you let me know how you'd like to proceed? Thank you!

Thank you for opening that! I left a small comment for the Go version PR, could you address that? After that we can move PRs move forward.

[tenzen-y]

@pierluigilenoci, could you rebase this PR on top of the master branch? Because we merged your Go version updating PR to the master branch.

[pierluigilenoci]

Hi @tenzen-y, I've rebased onto master (now includes the Go 1.26.0 bump from #796) and moved the flag initialization to cmd/mpi-operator/app/options/options.go as requested. Thank you!

[tenzen-y]

Awesome, thank you!
/lgtm
/approve

[google-oss-prow]

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