fix: honor -stderrthreshold when -logtostderr=true

klog v2 defaults -logtostderr to true, which silently ignores
-stderrthreshold — all severities are unconditionally sent to stderr.

Bump klog to v2.140.0 and opt into the fixed behavior by setting
legacy_stderr_threshold_behavior=false so that -stderrthreshold is
respected. The default is set to INFO (preserving current behavior);
users can now override it on the command line.

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

Signed-off-by: Pierluigi Lenoci <pierluigi.lenoci@gmail.com>
Signed-off-by: Pierluigi Lenoci <pierluigilenoci@gmail.com>

Author: pierluigilenoci

cmd/root.go

@@ -314,6 +314,11 @@ func disableKlog() {
 
 	flagSet = &flag.FlagSet{}
 	klogv2.InitFlags(flagSet)
+	// Opt into the new klog behavior so that -stderrthreshold is honored even
+	// when -logtostderr=true (the default).
+	// Ref: kubernetes/klog#212, kubernetes/klog#432
+	_ = flagSet.Set("legacy_stderr_threshold_behavior", "false")
+	_ = flagSet.Set("stderrthreshold", "INFO")
 	_ = flagSet.Set("logtostderr", "false")
 	klogv2.SetOutput(io.Discard)
 }

go.mod

@@ -65,7 +65,7 @@ require (
 	k8s.io/apimachinery v0.35.0
 	k8s.io/client-go v0.35.0
 	k8s.io/klog v1.0.0
-	k8s.io/klog/v2 v2.130.1
+k8s.io/klog/v2 v2.140.0
 	k8s.io/kubectl v0.35.0
 	mvdan.cc/sh/v3 v3.5.1
 	sigs.k8s.io/yaml v1.6.0

go.sum

@@ -838,6 +838,14 @@ k8s.io/kubectl v0.35.0 h1:cL/wJKHDe8E8+rP3G7avnymcMg6bH6JEcR5w5uo06wc=
 k8s.io/kubectl v0.35.0/go.mod h1:VR5/TSkYyxZwrRwY5I5dDq6l5KXmiCb+9w8IKplk3Qo=
 k8s.io/utils v0.0.0-20251002143259-bc988d571ff4 h1:SjGebBtkBqHFOli+05xYbK8YF1Dzkbzn+gDM4X9T4Ck=
 k8s.io/utils v0.0.0-20251002143259-bc988d571ff4/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=
+k8s.io/klog/v2 v2.140.0 h1:Tf+J3AH7xnUzZyVVXhTgGhEKnFqye14aadWv7bzXdzc=
+k8s.io/klog/v2 v2.140.0/go.mod h1:o+/RWfJ6PwpnFn7OyAG3QnO47BFsymfEfrz6XyYSSp0=
+k8s.io/kube-openapi v0.0.0-20231010175941-2dd684a91f00 h1:aVUu9fTY98ivBPKR9Y5w/AuzbMm96cd3YHRTU83I780=
+k8s.io/kube-openapi v0.0.0-20231010175941-2dd684a91f00/go.mod h1:AsvuZPBlUDVuCdzJ87iajxtXuR9oktsTctW/R9wwouA=
+k8s.io/kubectl v0.29.0 h1:Oqi48gXjikDhrBF67AYuZRTcJV4lg2l42GmvsP7FmYI=
+k8s.io/kubectl v0.29.0/go.mod h1:0jMjGWIcMIQzmUaMgAzhSELv5WtHo2a8pq67DtviAJs=
+k8s.io/utils v0.0.0-20230726121419-3b25d923346b h1:sgn3ZU783SCgtaSJjpcVVlRqd6GSnlTLKgpAAttJvpI=
+k8s.io/utils v0.0.0-20230726121419-3b25d923346b/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=
 mvdan.cc/sh/v3 v3.5.1 h1:hmP3UOw4f+EYexsJjFxvU38+kn+V/s2CclXHanIBkmQ=
 mvdan.cc/sh/v3 v3.5.1/go.mod h1:1JcoyAKm1lZw/2bZje/iYKWicU/KMd0rsyJeKHnsK4E=
 sigs.k8s.io/json v0.0.0-20250730193827-2d320260d730 h1:IpInykpT6ceI+QxKBbEflcR5EXP7sU1kvOlxwZh5txg=