Fix LoggingAlphaOptions wiring

Using --feature-gates=LoggingAlphaOptions=true resulted in the
descheduler not starting due to the feature gate not being recognised.

cmd/descheduler/app/server.go

@@ -28,13 +28,13 @@ import (
 
 	"sigs.k8s.io/descheduler/cmd/descheduler/app/options"
 	"sigs.k8s.io/descheduler/pkg/descheduler"
+	"sigs.k8s.io/descheduler/pkg/features"
 	"sigs.k8s.io/descheduler/pkg/tracing"
 
 	"k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/apiserver/pkg/server/healthz"
 	"k8s.io/apiserver/pkg/server/mux"
-	"k8s.io/component-base/featuregate"
 	"k8s.io/component-base/logs"
 	logsapi "k8s.io/component-base/logs/api/v1"
 	_ "k8s.io/component-base/logs/json/register"
@@ -49,7 +49,6 @@ func NewDeschedulerCommand(out io.Writer) *cobra.Command {
 		klog.ErrorS(err, "unable to initialize server")
 	}
 
-	featureGate := featuregate.NewFeatureGate()
 	logConfig := logsapi.NewLoggingConfiguration()
 
 	cmd := &cobra.Command{
@@ -58,7 +57,10 @@ func NewDeschedulerCommand(out io.Writer) *cobra.Command {
 		Long:  "The descheduler evicts pods which may be bound to less desired nodes",
 		PreRunE: func(cmd *cobra.Command, args []string) error {
 			logs.InitLogs()
-			if logsapi.ValidateAndApply(logConfig, featureGate); err != nil {
+			if err := features.DefaultMutableFeatureGate.SetFromMap(s.FeatureGates); err != nil {
+				return err
+			}
+			if err := logsapi.ValidateAndApply(logConfig, features.DefaultMutableFeatureGate); err != nil {
 				return err
 			}
 			descheduler.SetupPlugins()
@@ -80,9 +82,9 @@ func NewDeschedulerCommand(out io.Writer) *cobra.Command {
 	}
 	cmd.SetOut(out)
 	flags := cmd.Flags()
+	runtime.Must(logsapi.AddFeatureGates(features.DefaultMutableFeatureGate))
 	s.AddFlags(flags)
 
-	runtime.Must(logsapi.AddFeatureGates(featureGate))
 	logsapi.AddFlags(logConfig, flags)
 
 	return cmd

cmd/descheduler/app/server_test.go

@@ -0,0 +1,71 @@
+/*
+Copyright 2026 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package app
+
+import (
+	"io"
+	"strings"
+	"testing"
+)
+
+func TestNewDeschedulerCommand_LoggingAlphaOptions(t *testing.T) {
+	tests := []struct {
+		name    string
+		args    []string
+		wantErr string
+	}{
+		{
+			name: "LoggingAlphaOptions=false rejects --log-json-split-stream",
+			args: []string{
+				"--logging-format=json",
+				"--log-json-split-stream",
+				"--feature-gates=LoggingAlphaOptions=false",
+			},
+			wantErr: "LoggingAlphaOptions is disabled",
+		},
+		{
+			name: "LoggingAlphaOptions=true accepts --log-json-split-stream",
+			args: []string{
+				"--logging-format=json",
+				"--log-json-split-stream",
+				"--feature-gates=LoggingAlphaOptions=true",
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			cmd := NewDeschedulerCommand(io.Discard)
+			if err := cmd.ParseFlags(tc.args); err != nil {
+				t.Fatalf("ParseFlags(%v): %v", tc.args, err)
+			}
+			err := cmd.PreRunE(cmd, cmd.Flags().Args())
+			if tc.wantErr == "" {
+				if err != nil {
+					t.Fatalf("expected PreRunE to succeed, got error: %v", err)
+				}
+				return
+			}
+			if err == nil {
+				t.Fatalf("expected PreRunE to fail with %q, got nil", tc.wantErr)
+			}
+			if !strings.Contains(err.Error(), tc.wantErr) {
+				t.Fatalf("expected PreRunE error to contain %q, got :%v", tc.wantErr, err)
+			}
+		})
+	}
+}

pkg/features/features.go

@@ -46,4 +46,4 @@ var defaultDeschedulerFeatureGates = map[featuregate.Feature]featuregate.Feature
 // Tests that need to modify feature gates for the duration of their test should use:
 //
 //	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.<FeatureName>, <value>)()
-var DefaultMutableFeatureGate featuregate.MutableFeatureGate = featuregate.NewFeatureGate()
+var DefaultMutableFeatureGate featuregate.MutableVersionedFeatureGate = featuregate.NewFeatureGate()