fixed crash when channel is closed (#273)

cli/cmd/tapRunner.go

@@ -379,13 +379,28 @@ func watchPodsForTapping(ctx context.Context, kubernetesProvider *kubernetes.Pro
 
 	for {
 		select {
-		case pod := <-added:
+		case pod, ok := <-added:
+			if !ok {
+				added = nil
+				continue
+			}
+
 			logger.Log.Debugf("Added matching pod %s, ns: %s", pod.Name, pod.Namespace)
 			restartTappersDebouncer.SetOn()
-		case pod := <-removed:
+		case pod, ok := <-removed:
+			if !ok {
+				removed = nil
+				continue
+			}
+
 			logger.Log.Debugf("Removed matching pod %s, ns: %s", pod.Name, pod.Namespace)
 			restartTappersDebouncer.SetOn()
-		case pod := <-modified:
+		case pod, ok := <-modified:
+			if !ok {
+				modified = nil
+				continue
+			}
+
 			logger.Log.Debugf("Modified matching pod %s, ns: %s, phase: %s, ip: %s", pod.Name, pod.Namespace, pod.Status.Phase, pod.Status.PodIP)
 			// Act only if the modified pod has already obtained an IP address.
 			// After filtering for IPs, on a normal pod restart this includes the following events:
@@ -396,8 +411,12 @@ func watchPodsForTapping(ctx context.Context, kubernetesProvider *kubernetes.Pro
 			if pod.Status.PodIP != "" {
 				restartTappersDebouncer.SetOn()
 			}
+		case err, ok := <-errorChan:
+			if !ok {
+				errorChan = nil
+				continue
+			}
 
-		case err := <-errorChan:
 			logger.Log.Debugf("Watching pods loop, got error %v, stopping `restart tappers debouncer`", err)
 			restartTappersDebouncer.Cancel()
 			// TODO: Does this also perform cleanup?
@@ -477,21 +496,28 @@ func watchApiServerPod(ctx context.Context, kubernetesProvider *kubernetes.Provi
 	timeAfter := time.After(25 * time.Second)
 	for {
 		select {
-		case <-ctx.Done():
+		case _, ok := <-added:
-			logger.Log.Debugf("Watching API Server pod loop, ctx done")
+			if !ok {
-			return
+				added = nil
-		case <-added:
+				continue
+			}
+
 			logger.Log.Debugf("Watching API Server pod loop, added")
-			continue
+		case _, ok := <-removed:
-		case <-removed:
+			if !ok {
+				removed = nil
+				continue
+			}
+
 			logger.Log.Infof("%s removed", mizu.ApiServerPodName)
 			cancel()
 			return
-		case modifiedPod := <-modified:
+		case modifiedPod, ok := <-modified:
-			if modifiedPod == nil {
+			if !ok {
-				logger.Log.Debugf("Watching API Server pod loop, modifiedPod with nil")
+				modified = nil
 				continue
 			}
+
 			logger.Log.Debugf("Watching API Server pod loop, modified: %v", modifiedPod.Status.Phase)
 			if modifiedPod.Status.Phase == core.PodRunning && !isPodReady {
 				isPodReady = true
@@ -510,14 +536,23 @@ func watchApiServerPod(ctx context.Context, kubernetesProvider *kubernetes.Provi
 					logger.Log.Debugf("[Error] failed update tapped pods %v", err)
 				}
 			}
+		case _, ok := <-errorChan:
+			if !ok {
+				errorChan = nil
+				continue
+			}
+
+			logger.Log.Debugf("[ERROR] Agent creation, watching %v namespace", config.Config.MizuResourcesNamespace)
+			cancel()
+
 		case <-timeAfter:
 			if !isPodReady {
 				logger.Log.Errorf(uiUtils.Error, "Mizu API server was not ready in time")
 				cancel()
 			}
-		case <-errorChan:
+		case <-ctx.Done():
-			logger.Log.Debugf("[ERROR] Agent creation, watching %v namespace", config.Config.MizuResourcesNamespace)
+			logger.Log.Debugf("Watching API Server pod loop, ctx done")
-			cancel()
+			return
 		}
 	}
 }