Update targeted pods on resolution history change

Author: corest

pkg/kubernetes/watcher.go

@@ -10,35 +10,41 @@ import (
 	k8serrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/kubernetes"
 	restclient "k8s.io/client-go/rest"
 )
 
+const (
+	kubesharkConfigmapName    = "kubeshark-config-map"
+	resolverHistoryAnnotation = "resolver.kubeshark.io/history"
+)
+
 type Watcher struct {
-	clientConfig *restclient.Config
-	clientSet    *kubernetes.Clientset
-	regex        *regexp.Regexp
-	namespaces   []string
-	isStarted    bool
-	errOut       chan error
-	callback     func(pods []v1.Pod) error
+	clientConfig  *restclient.Config
+	clientSet     *kubernetes.Clientset
+	regex         *regexp.Regexp
+	namespaces    []string
+	isStarted     bool
+	lastUpdatedAt string
+	errOut        chan error
+	callback      func(pods []v1.Pod) error
 }
 
 func (watcher *Watcher) Start(ctx context.Context, clusterMode bool) {
 	if !watcher.isStarted {
 		watcher.isStarted = true
 
 		if clusterMode {
-			go watcher.infiniteErrorHandleRetryFunc(ctx, watcher.watchConfigMap)
-			go watcher.infiniteErrorHandleRetryFunc(ctx, watcher.watchPods)
+			go watcher.infiniteErrorHandleRetryFunc(ctx, watcher.watchKubesharkConfigMap)
 		}
 	}
 }
 
-func (watcher *Watcher) watchConfigMap(ctx context.Context) error {
+func (watcher *Watcher) watchKubesharkConfigMap(ctx context.Context) error {
 	w, err := watcher.clientSet.CoreV1().ConfigMaps(GetSelfNamespace()).Watch(ctx, metav1.ListOptions{
 		Watch:         true,
-		FieldSelector: fields.OneTermEqualSelector(metav1.ObjectNameField, "kubeshark-config-map").String(),
+		FieldSelector: fields.OneTermEqualSelector(metav1.ObjectNameField, kubesharkConfigmapName).String(),
 	})
 	if err != nil {
 		return err
@@ -48,52 +54,16 @@ func (watcher *Watcher) watchConfigMap(ctx context.Context) error {
 		select {
 		case event := <-w.ResultChan():
 			if event.Object == nil {
-				return errors.New("error in kubectl endpoint watch")
-			}
-			watcher.regex, watcher.namespaces = SyncConfig(event.Object.(*v1.ConfigMap))
-
-			err = updateCurrentlyTargetedPods(ctx, watcher.clientSet, watcher.regex, watcher.namespaces, watcher.callback)
-			if err != nil {
-				log.Error().Err(err).Send()
-			}
-		case <-ctx.Done():
-			w.Stop()
-			return nil
-		}
-	}
-}
-
-func (watcher *Watcher) watchPods(ctx context.Context) error {
-	// empty namespace makes the client watch all namespaces
-	kubesharkLabels := map[string]string{"app.kubernetes.io/name": "kubeshark"}
-	w, err := watcher.clientSet.CoreV1().Pods(allNamespaces).Watch(ctx, metav1.ListOptions{Watch: true})
-	if err != nil {
-		w, err = watcher.clientSet.CoreV1().Pods(GetSelfNamespace()).Watch(ctx, metav1.ListOptions{Watch: true})
-		if err != nil {
-			return err
-		}
-	}
-	if err != nil {
-		return err
-	}
-	for {
-		select {
-		case event := <-w.ResultChan():
-			if event.Object == nil {
-				return errors.New("error in kubectl pod watch")
-			}
-
-			pod := event.Object.(*v1.Pod)
-			if mapsContain(pod.ObjectMeta.Labels, kubesharkLabels) {
-				// ignore kubeshark pods
-				continue
+				return errors.New("error in kubeshark configmap watch")
 			}
+			if watcher.isHistoryUpdated(&event) {
+				watcher.regex, watcher.namespaces = SyncConfig(event.Object.(*v1.ConfigMap))
 
-			log.Debug().Str("event", string(event.Type)).Str("pod-name", pod.Name).Str("namespace", pod.Namespace).Send()
-
-			err = updateCurrentlyTargetedPods(ctx, watcher.clientSet, watcher.regex, watcher.namespaces, watcher.callback)
-			if err != nil {
-				log.Error().Err(err).Send()
+				err = updateCurrentlyTargetedPods(ctx, watcher.clientSet, watcher.regex, watcher.namespaces, watcher.callback)
+				if err != nil {
+					log.Error().Err(err).Send()
+				}
+				watcher.lastUpdatedAt = event.Object.(*v1.ConfigMap).ObjectMeta.Annotations[resolverHistoryAnnotation]
 			}
 		case <-ctx.Done():
 			w.Stop()
@@ -121,3 +91,14 @@ func (watcher *Watcher) infiniteErrorHandleRetryFunc(ctx context.Context, fun fu
 		}
 	}
 }
+
+func (watcher *Watcher) isHistoryUpdated(event *watch.Event) bool {
+	cm := event.Object.(*v1.ConfigMap)
+	currentUpdatedAt := cm.ObjectMeta.Annotations[resolverHistoryAnnotation]
+
+	if watcher.lastUpdatedAt != currentUpdatedAt || currentUpdatedAt == "" {
+		return true
+	}
+
+	return false
+}