Merge pull request #135358 from harche/sort_hanlders

Sort runtime handlers list coming from the CRI runtime

pkg/kubelet/runtime.go

@@ -19,6 +19,7 @@ package kubelet
 import (
 	"errors"
 	"fmt"
+	"sort"
 	"sync"
 	"time"
 
@@ -75,7 +76,11 @@ func (s *runtimeState) setRuntimeState(err error) {
 func (s *runtimeState) setRuntimeHandlers(rtHandlers []kubecontainer.RuntimeHandler) {
 	s.Lock()
 	defer s.Unlock()
-	s.rtHandlers = rtHandlers
+	// Copy and sort to ensure deterministic ordering of runtime handlers and avoid spurious Node status updates.
+	s.rtHandlers = append([]kubecontainer.RuntimeHandler(nil), rtHandlers...)
+	sort.Slice(s.rtHandlers, func(i, j int) bool {
+		return s.rtHandlers[i].Name < s.rtHandlers[j].Name
+	})
 }
 
 func (s *runtimeState) runtimeHandlers() []kubecontainer.RuntimeHandler {

pkg/kubelet/runtime_test.go

@@ -0,0 +1,80 @@
+/*
+Copyright 2025 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 kubelet
+
+import (
+	"reflect"
+	"testing"
+
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+)
+
+func TestRuntimeStateSetRuntimeHandlersSortsAndCopies(t *testing.T) {
+	testCases := []struct {
+		name     string
+		handlers []kubecontainer.RuntimeHandler
+		expected []string
+	}{
+		{
+			name: "unsortedWithDefault",
+			handlers: []kubecontainer.RuntimeHandler{
+				{Name: "runc"},
+				{Name: ""},
+				{Name: "crun"},
+			},
+			expected: []string{"", "crun", "runc"},
+		},
+		{
+			name: "alreadySorted",
+			handlers: []kubecontainer.RuntimeHandler{
+				{Name: ""},
+				{Name: "crun"},
+				{Name: "runc"},
+			},
+			expected: []string{"", "crun", "runc"},
+		},
+		{
+			name:     "emptyHandlers",
+			handlers: nil,
+			expected: []string{},
+		},
+	}
+
+	for _, tt := range testCases {
+		t.Run(tt.name, func(t *testing.T) {
+			state := &runtimeState{}
+			input := append([]kubecontainer.RuntimeHandler(nil), tt.handlers...)
+			original := append([]kubecontainer.RuntimeHandler(nil), input...)
+
+			state.setRuntimeHandlers(input)
+
+			if !reflect.DeepEqual(input, original) {
+				t.Fatalf("setRuntimeHandlers mutated input slice: got %#v, want %#v", input, original)
+			}
+
+			got := state.runtimeHandlers()
+			if len(got) != len(tt.expected) {
+				t.Fatalf("unexpected handler count: got %d, want %d", len(got), len(tt.expected))
+			}
+			for i, name := range tt.expected {
+				if got[i].Name != name {
+					t.Errorf("unexpected handler order at %d: got %q, want %q", i, got[i].Name, name)
+				}
+			}
+		})
+	}
+}