fix daemon set rolling update hang

Author: daihao

pkg/controller/daemon/daemon_controller.go

@@ -535,6 +535,15 @@ func (dsc *DaemonSetsController) updatePod(old, cur interface{}) {
 		return
 	}
 
+	if curPod.DeletionTimestamp != nil {
+		// when a pod is deleted gracefully its deletion timestamp is first modified to reflect a grace period,
+		// and after such time has passed, the kubelet actually deletes it from the store. We receive an update
+		// for modification of the deletion timestamp and expect an ds to create more replicas asap, not wait
+		// until the kubelet actually deletes the pod.
+		dsc.deletePod(curPod)
+		return
+	}
+
 	curControllerRef := metav1.GetControllerOf(curPod)
 	oldControllerRef := metav1.GetControllerOf(oldPod)
 	controllerRefChanged := !reflect.DeepEqual(curControllerRef, oldControllerRef)