fix(pluginwatcher): watch socket dir before traversing it

Signed-off-by: knight42 <anonymousknight96@gmail.com>

pkg/kubelet/pluginmanager/plugin_manager_test.go

@@ -20,6 +20,9 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"path/filepath"
+	"reflect"
+	"strconv"
 	"sync"
 	"testing"
 	"time"
@@ -29,6 +32,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/tools/record"
 	registerapi "k8s.io/kubelet/pkg/apis/pluginregistration/v1"
+
 	"k8s.io/kubernetes/pkg/kubelet/config"
 	"k8s.io/kubernetes/pkg/kubelet/pluginmanager/pluginwatcher"
 )
@@ -39,25 +43,19 @@ var (
 )
 
 type fakePluginHandler struct {
-	validatePluginCalled   bool
-	registerPluginCalled   bool
-	deregisterPluginCalled bool
+	events []string
 	sync.RWMutex
 }
 
 func newFakePluginHandler() *fakePluginHandler {
-	return &fakePluginHandler{
-		validatePluginCalled:   false,
-		registerPluginCalled:   false,
-		deregisterPluginCalled: false,
-	}
+	return &fakePluginHandler{}
 }
 
 // ValidatePlugin is a fake method
 func (f *fakePluginHandler) ValidatePlugin(pluginName string, endpoint string, versions []string) error {
 	f.Lock()
 	defer f.Unlock()
-	f.validatePluginCalled = true
+	f.events = append(f.events, "validate "+pluginName)
 	return nil
 }
 
@@ -65,7 +63,7 @@ func (f *fakePluginHandler) ValidatePlugin(pluginName string, endpoint string, v
 func (f *fakePluginHandler) RegisterPlugin(pluginName, endpoint string, versions []string) error {
 	f.Lock()
 	defer f.Unlock()
-	f.registerPluginCalled = true
+	f.events = append(f.events, "register "+pluginName)
 	return nil
 }
 
@@ -73,7 +71,13 @@ func (f *fakePluginHandler) RegisterPlugin(pluginName, endpoint string, versions
 func (f *fakePluginHandler) DeRegisterPlugin(pluginName string) {
 	f.Lock()
 	defer f.Unlock()
-	f.deregisterPluginCalled = true
+	f.events = append(f.events, "deregister "+pluginName)
+}
+
+func (f *fakePluginHandler) Reset() {
+	f.Lock()
+	defer f.Unlock()
+	f.events = nil
 }
 
 func init() {
@@ -90,15 +94,17 @@ func cleanup(t *testing.T) {
 	os.MkdirAll(socketDir, 0755)
 }
 
-func waitForRegistration(t *testing.T, fakePluginHandler *fakePluginHandler) {
+func waitForRegistration(t *testing.T, fakePluginHandler *fakePluginHandler, pluginName string) {
+	expected := []string{"validate " + pluginName, "register " + pluginName}
 	err := retryWithExponentialBackOff(
-		time.Duration(500*time.Millisecond),
+		100*time.Millisecond,
 		func() (bool, error) {
 			fakePluginHandler.Lock()
 			defer fakePluginHandler.Unlock()
-			if fakePluginHandler.validatePluginCalled && fakePluginHandler.registerPluginCalled {
+			if reflect.DeepEqual(fakePluginHandler.events, expected) {
 				return true, nil
 			}
+			t.Logf("expected %#v, got %#v, will retry", expected, fakePluginHandler.events)
 			return false, nil
 		},
 	)
@@ -134,19 +140,29 @@ func TestPluginRegistration(t *testing.T) {
 	fakeHandler := newFakePluginHandler()
 	pluginManager.AddHandler(registerapi.DevicePlugin, fakeHandler)
 
-	// Add a new plugin
-	socketPath := fmt.Sprintf("%s/plugin.sock", socketDir)
-	pluginName := "example-plugin"
-	p := pluginwatcher.NewTestExamplePlugin(pluginName, registerapi.DevicePlugin, socketPath, supportedVersions...)
-	require.NoError(t, p.Serve("v1beta1", "v1beta2"))
+	const maxDepth = 3
+	// Make sure the plugin manager is aware of the socket in subdirectories
+	for i := 0; i < maxDepth; i++ {
+		fakeHandler.Reset()
+		pluginDir := socketDir
 
-	// Verify that the plugin is registered
-	waitForRegistration(t, fakeHandler)
+		for j := 0; j < i; j++ {
+			pluginDir = filepath.Join(pluginDir, strconv.Itoa(j))
+		}
+		require.NoError(t, os.MkdirAll(pluginDir, os.ModePerm))
+		socketPath := filepath.Join(pluginDir, fmt.Sprintf("plugin-%d.sock", i))
+
+		// Add a new plugin
+		pluginName := fmt.Sprintf("example-plugin-%d", i)
+		p := pluginwatcher.NewTestExamplePlugin(pluginName, registerapi.DevicePlugin, socketPath, supportedVersions...)
+		require.NoError(t, p.Serve("v1beta1", "v1beta2"))
+
+		// Verify that the plugin is registered
+		waitForRegistration(t, fakeHandler, pluginName)
+	}
 }
 
-func newTestPluginManager(
-	sockDir string) PluginManager {
-
+func newTestPluginManager(sockDir string) PluginManager {
 	pm := NewPluginManager(
 		sockDir,
 		&record.FakeRecorder{},

pkg/kubelet/pluginmanager/pluginwatcher/plugin_watcher.go

@@ -21,7 +21,6 @@ import (
 	"os"
 	"runtime"
 	"strings"
-	"time"
 
 	"github.com/fsnotify/fsnotify"
 	"k8s.io/klog/v2"
@@ -36,7 +35,6 @@ type Watcher struct {
 	path                string
 	fs                  utilfs.Filesystem
 	fsWatcher           *fsnotify.Watcher
-	stopped             chan struct{}
 	desiredStateOfWorld cache.DesiredStateOfWorld
 }
 
@@ -53,8 +51,6 @@ func NewWatcher(sockDir string, desiredStateOfWorld cache.DesiredStateOfWorld) *
 func (w *Watcher) Start(stopCh <-chan struct{}) error {
 	klog.V(2).Infof("Plugin Watcher Start at %s", w.path)
 
-	w.stopped = make(chan struct{})
-
 	// Creating the directory to be watched if it doesn't exist yet,
 	// and walks through the directory to discover the existing plugins.
 	if err := w.init(); err != nil {
@@ -73,7 +69,6 @@ func (w *Watcher) Start(stopCh <-chan struct{}) error {
 	}
 
 	go func(fsWatcher *fsnotify.Watcher) {
-		defer close(w.stopped)
 		for {
 			select {
 			case event := <-fsWatcher.Events:
@@ -93,14 +88,6 @@ func (w *Watcher) Start(stopCh <-chan struct{}) error {
 				}
 				continue
 			case <-stopCh:
-				// In case of plugin watcher being stopped by plugin manager, stop
-				// probing the creation/deletion of plugin sockets.
-				// Also give all pending go routines a chance to complete
-				select {
-				case <-w.stopped:
-				case <-time.After(11 * time.Second):
-					klog.Errorf("timeout on stopping watcher")
-				}
 				w.fsWatcher.Close()
 				return
 			}
@@ -123,6 +110,12 @@ func (w *Watcher) init() error {
 // Walks through the plugin directory discover any existing plugin sockets.
 // Ignore all errors except root dir not being walkable
 func (w *Watcher) traversePluginDir(dir string) error {
+	// watch the new dir
+	err := w.fsWatcher.Add(dir)
+	if err != nil {
+		return fmt.Errorf("failed to watch %s, err: %v", w.path, err)
+	}
+	// traverse existing children in the dir
 	return w.fs.Walk(dir, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			if path == dir {
@@ -133,6 +126,11 @@ func (w *Watcher) traversePluginDir(dir string) error {
 			return nil
 		}
 
+		// do not call fsWatcher.Add twice on the root dir to avoid potential problems.
+		if path == dir {
+			return nil
+		}
+
 		switch mode := info.Mode(); {
 		case mode.IsDir():
 			if err := w.fsWatcher.Add(path); err != nil {