Refactors kubelet's plugin watcher

Refactors platform specific code into separate files (*_linux.go / *_windows.go / *_others.go)

Adds unit tests for the pluginwatcher changes.

pkg/kubelet/pluginmanager/pluginwatcher/plugin_watcher.go

@@ -19,7 +19,6 @@ package pluginwatcher
 import (
 	"fmt"
 	"os"
-	"runtime"
 	"strings"
 
 	"github.com/fsnotify/fsnotify"
@@ -159,13 +158,7 @@ func (w *Watcher) traversePluginDir(dir string) error {
 func (w *Watcher) handleCreateEvent(event fsnotify.Event) error {
 	klog.V(6).InfoS("Handling create event", "event", event)
 
-	fi, err := os.Stat(event.Name)
-	// TODO: This is a workaround for Windows 20H2 issue for os.Stat(). Please see
-	// microsoft/Windows-Containers#97 for details.
-	// Once the issue is resvolved, the following os.Lstat() is not needed.
-	if err != nil && runtime.GOOS == "windows" {
-		fi, err = os.Lstat(event.Name)
-	}
+	fi, err := getStat(event)
 	if err != nil {
 		return fmt.Errorf("stat file %s failed: %v", event.Name, err)
 	}
@@ -192,9 +185,7 @@ func (w *Watcher) handleCreateEvent(event fsnotify.Event) error {
 }
 
 func (w *Watcher) handlePluginRegistration(socketPath string) error {
-	if runtime.GOOS == "windows" {
-		socketPath = util.NormalizePath(socketPath)
-	}
+	socketPath = getSocketPath(socketPath)
 	// Update desired state of world list of plugins
 	// If the socket path does exist in the desired world cache, there's still
 	// a possibility that it has been deleted and recreated again before it is

pkg/kubelet/pluginmanager/pluginwatcher/plugin_watcher_others.go

@@ -0,0 +1,34 @@
+//go:build !windows
+// +build !windows
+
+/*
+Copyright 2023 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 pluginwatcher
+
+import (
+	"os"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+func getStat(event fsnotify.Event) (os.FileInfo, error) {
+	return os.Stat(event.Name)
+}
+
+func getSocketPath(socketPath string) string {
+	return socketPath
+}

pkg/kubelet/pluginmanager/pluginwatcher/plugin_watcher_others_test.go

@@ -0,0 +1,42 @@
+//go:build !windows
+// +build !windows
+
+/*
+Copyright 2023 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 pluginwatcher
+
+import (
+	"os"
+	"testing"
+
+	"github.com/fsnotify/fsnotify"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetStat(t *testing.T) {
+	event := fsnotify.Event{Name: "name", Op: fsnotify.Create}
+	fi, err := getStat(event)
+	fiExpected, errExpected := os.Stat(event.Name)
+
+	assert.Equal(t, fi, fiExpected)
+	assert.Equal(t, err, errExpected)
+}
+
+func TestGetSocketPath(t *testing.T) {
+	socketPath := "/tmp/foo/lish.sock"
+	assert.Equal(t, socketPath, getSocketPath(socketPath))
+}

pkg/kubelet/pluginmanager/pluginwatcher/plugin_watcher_windows.go

@@ -0,0 +1,40 @@
+//go:build windows
+// +build windows
+
+/*
+Copyright 2023 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 pluginwatcher
+
+import (
+	"github.com/fsnotify/fsnotify"
+	"k8s.io/kubernetes/pkg/kubelet/util"
+	"os"
+)
+
+func getStat(event fsnotify.Event) (os.FileInfo, error) {
+	fi, err := os.Stat(event.Name)
+	// TODO: This is a workaround for Windows 20H2 issue for os.Stat(). Please see
+	// microsoft/Windows-Containers#97 for details.
+	// Once the issue is resvolved, the following os.Lstat() is not needed.
+	if err != nil {
+		fi, err = os.Lstat(event.Name)
+	}
+
+	return fi, err
+}
+
+var getSocketPath = util.NormalizePath

pkg/kubelet/pluginmanager/pluginwatcher/plugin_watcher_windows_test.go

@@ -0,0 +1,43 @@
+//go:build windows
+// +build windows
+
+/*
+Copyright 2023 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 pluginwatcher
+
+import (
+	"os"
+	"testing"
+
+	"github.com/fsnotify/fsnotify"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetStatWindows(t *testing.T) {
+	event := fsnotify.Event{Name: "name", Op: fsnotify.Create}
+	fi, err := getStat(event)
+	fiExpected, errExpected := os.Stat(event.Name)
+	// TODO: This is a workaround for Windows 20H2 issue for os.Stat(). Please see
+	// microsoft/Windows-Containers#97 for details.
+	// Once the issue is resvolved, the following os.Lstat() is not needed.
+	if errExpected != nil {
+		fiExpected, errExpected = os.Lstat(event.Name)
+	}
+
+	assert.Equal(t, fi, fiExpected)
+	assert.Equal(t, err, errExpected)
+}