nfd-worker: Watch features.d changes

pkg/nfd-worker/nfd-worker.go

@@ -121,6 +121,7 @@ type nfdWorker struct {
 	k8sClient           k8sclient.Interface
 	nfdClient           nfdclient.Interface
 	stop                chan struct{} // channel for signaling stop
+	sourceEvent         chan struct{} // channel for events from soures
 	featureSources      []source.FeatureSource
 	labelSources        []source.LabelSource
 	ownerReference      []metav1.OwnerReference
@@ -304,6 +305,12 @@ func (w *nfdWorker) Run() error {
 	labelTrigger.Reset(w.config.Core.SleepInterval.Duration)
 	defer labelTrigger.Stop()
 
+	w.sourceEvent = make(chan struct{})
+	eventSources := source.GetAllEventSources()
+	for _, s := range eventSources {
+		s.SetChannel(w.sourceEvent)
+	}
+
 	httpMux := http.NewServeMux()
 
 	// Register to metrics server
@@ -341,6 +348,12 @@ func (w *nfdWorker) Run() error {
 				return err
 			}
 
+		case <-w.sourceEvent:
+			err = w.runFeatureDiscovery()
+			if err != nil {
+				return err
+			}
+
 		case <-w.stop:
 			klog.InfoS("shutting down nfd-worker")
 			return nil

source/local/local.go

@@ -26,6 +26,7 @@ import (
 
 	"k8s.io/klog/v2"
 
+	"github.com/fsnotify/fsnotify"
 	nfdv1alpha1 "sigs.k8s.io/node-feature-discovery/api/nfd/v1alpha1"
 	"sigs.k8s.io/node-feature-discovery/pkg/utils"
 	"sigs.k8s.io/node-feature-discovery/source"
@@ -65,10 +66,11 @@ var (
 	featureFilesDir = "/etc/kubernetes/node-feature-discovery/features.d/"
 )
 
-// localSource implements the FeatureSource and LabelSource interfaces.
+// localSource implements the FeatureSource, LabelSource, EventSource interfaces.
 type localSource struct {
-	features *nfdv1alpha1.Features
-	config   *Config
+	features  *nfdv1alpha1.Features
+	config    *Config
+	fsWatcher *fsnotify.Watcher
 }
 
 type Config struct {
@@ -87,6 +89,7 @@ var (
 	_   source.FeatureSource      = &src
 	_   source.LabelSource        = &src
 	_   source.ConfigurableSource = &src
+	_   source.EventSource        = &src
 )
 
 // Name method of the LabelSource interface
@@ -318,6 +321,47 @@ func getFileContent(fileName string) ([][]byte, error) {
 	return lines, nil
 }
 
+func (s *localSource) runNotifier(ch chan struct{}) {
+	for {
+		select {
+		case event := <-s.fsWatcher.Events:
+			if event.Op&fsnotify.Create == fsnotify.Create || event.Op&fsnotify.Write == fsnotify.Write || event.Op&fsnotify.Remove == fsnotify.Remove || event.Op&fsnotify.Rename == fsnotify.Rename || event.Op&fsnotify.Chmod == fsnotify.Chmod {
+				klog.InfoS("fsnotify event", event)
+				ch <- struct{}{}
+			}
+		case err := <-s.fsWatcher.Errors:
+			klog.ErrorS(err, "failed to to watch features.d changes")
+		}
+	}
+}
+
+// SetChannel method of the EventSource Interface
+func (s *localSource) SetChannel(ch chan struct{}) error {
+	info, err := os.Stat(featureFilesDir)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return err
+		}
+	}
+
+	if info != nil && info.IsDir() {
+		watcher, err := fsnotify.NewWatcher()
+		if err != nil {
+			return err
+		}
+
+		err = watcher.Add(featureFilesDir)
+		if err != nil {
+			return fmt.Errorf("unable to access %v: %w", featureFilesDir, err)
+		}
+		s.fsWatcher = watcher
+	}
+
+	go s.runNotifier(ch)
+
+	return nil
+}
+
 func init() {
 	source.Register(&src)
 }

source/source.go

@@ -77,6 +77,14 @@ type SupplementalSource interface {
 	DisableByDefault() bool
 }
 
+// EventSource is an interface for a source that can send events
+type EventSource interface {
+	Source
+
+	// SetChannel sets the channel
+	SetChannel(chan struct{}) error
+}
+
 // FeatureLabelValue represents the value of one feature label
 type FeatureLabelValue interface{}
 
@@ -155,6 +163,17 @@ func GetAllConfigurableSources() map[string]ConfigurableSource {
 	return all
 }
 
+// GetAllEventSources returns all registered event sources
+func GetAllEventSources() map[string]EventSource {
+	all := make(map[string]EventSource)
+	for k, v := range sources {
+		if s, ok := v.(EventSource); ok {
+			all[k] = s
+		}
+	}
+	return all
+}
+
 // GetAllFeatures returns a combined set of all features from all feature
 // sources.
 func GetAllFeatures() *nfdv1alpha1.Features {