From 752135242e49dc571159eb51328bcfc7734e6033 Mon Sep 17 00:00:00 2001
From: Derek Carr <decarr@redhat.com>
Date: Tue, 18 Aug 2020 15:24:03 -0400
Subject: [PATCH] WIP: node sync at least once

---
 pkg/kubelet/kubelet.go         | 37 +++++++++++++++++++++++++++-------
 pkg/kubelet/kubelet_getters.go | 13 +++++++++++-
 pkg/kubelet/kubelet_test.go    |  1 +
 3 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/pkg/kubelet/kubelet.go b/pkg/kubelet/kubelet.go
index b039ab963c5..c5d2ee6f0db 100644
--- a/pkg/kubelet/kubelet.go
+++ b/pkg/kubelet/kubelet.go
@@ -125,6 +125,9 @@ const (
 	// Max amount of time to wait for the container runtime to come up.
 	maxWaitForContainerRuntime = 30 * time.Second
 
+	// Max amount of time to wait for node list/watch to initially sync
+	maxWaitForAPIServerSync = 10 * time.Second
+
 	// nodeStatusUpdateRetry specifies how many times kubelet retries when posting node status failed.
 	nodeStatusUpdateRetry = 5
 
@@ -431,14 +434,31 @@ func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
 		serviceHasSynced = func() bool { return true }
 	}
 
-	nodeIndexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{})
+	var nodeHasSynced cache.InformerSynced
+	var nodeLister corelisters.NodeLister
+
 	if kubeDeps.KubeClient != nil {
-		fieldSelector := fields.Set{api.ObjectNameField: string(nodeName)}.AsSelector()
-		nodeLW := cache.NewListWatchFromClient(kubeDeps.KubeClient.CoreV1().RESTClient(), "nodes", metav1.NamespaceAll, fieldSelector)
-		r := cache.NewReflector(nodeLW, &v1.Node{}, nodeIndexer, 0)
-		go r.Run(wait.NeverStop)
+		kubeInformers := informers.NewSharedInformerFactoryWithOptions(kubeDeps.KubeClient, 0, informers.WithTweakListOptions(func(options *metav1.ListOptions) {
+			options.FieldSelector = fields.Set{api.ObjectNameField: string(nodeName)}.String()
+		}))
+		nodeLister = kubeInformers.Core().V1().Nodes().Lister()
+		nodeHasSynced = func() bool {
+			if kubeInformers.Core().V1().Nodes().Informer().HasSynced() {
+				klog.Infof("kubelet nodes sync")
+				return true
+			}
+			klog.Infof("kubelet nodes not sync")
+			return false
+		}
+		kubeInformers.Start(wait.NeverStop)
+		klog.Info("Kubelet client is not nil")
+	} else {
+		// we dont have a client to sync!
+		nodeIndexer := cache.NewIndexer(cache.MetaNamespaceKeyFunc, cache.Indexers{})
+		nodeLister = corelisters.NewNodeLister(nodeIndexer)
+		nodeHasSynced = func() bool { return true }
+		klog.Info("Kubelet client is nil")
 	}
-	nodeLister := corelisters.NewNodeLister(nodeIndexer)
 
 	// TODO: get the real node object of ourself,
 	// and use the real node name and UID.
@@ -489,6 +509,7 @@ func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
 		serviceLister:                           serviceLister,
 		serviceHasSynced:                        serviceHasSynced,
 		nodeLister:                              nodeLister,
+		nodeHasSynced:                           nodeHasSynced,
 		masterServiceNamespace:                  masterServiceNamespace,
 		streamingConnectionIdleTimeout:          kubeCfg.StreamingConnectionIdleTimeout.Duration,
 		recorder:                                kubeDeps.Recorder,
@@ -873,7 +894,9 @@ type Kubelet struct {
 	serviceHasSynced cache.InformerSynced
 	// nodeLister knows how to list nodes
 	nodeLister corelisters.NodeLister
-
+	// nodeHasSynced indicates whether nodes have been sync'd at least once.
+	// Check this before trusting a response from the node lister.
+	nodeHasSynced cache.InformerSynced
 	// a list of node labels to register
 	nodeLabels map[string]string
 
diff --git a/pkg/kubelet/kubelet_getters.go b/pkg/kubelet/kubelet_getters.go
index aed08db4c2f..dbe5ff53f43 100644
--- a/pkg/kubelet/kubelet_getters.go
+++ b/pkg/kubelet/kubelet_getters.go
@@ -22,6 +22,7 @@ import (
 	"io/ioutil"
 	"net"
 	"path/filepath"
+	"time"
 
 	cadvisorapiv1 "github.com/google/cadvisor/info/v1"
 	cadvisorv2 "github.com/google/cadvisor/info/v2"
@@ -32,6 +33,7 @@ import (
 
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/kubernetes/pkg/kubelet/cm"
 	"k8s.io/kubernetes/pkg/kubelet/config"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
@@ -235,6 +237,15 @@ func (kl *Kubelet) GetNode() (*v1.Node, error) {
 	if kl.kubeClient == nil {
 		return kl.initialNode(context.TODO())
 	}
+	// if we have a valid kube client, we wait for initial lister to sync
+	if !kl.nodeHasSynced() {
+		err := wait.PollImmediate(time.Second, maxWaitForAPIServerSync, func() (bool, error) {
+			return kl.nodeHasSynced(), nil
+		})
+		if err != nil {
+			return nil, fmt.Errorf("nodes have not yet been read at least once, cannot construct node object")
+		}
+	}
 	return kl.nodeLister.Get(string(kl.nodeName))
 }
 
@@ -245,7 +256,7 @@ func (kl *Kubelet) GetNode() (*v1.Node, error) {
 // zero capacity, and the default labels.
 func (kl *Kubelet) getNodeAnyWay() (*v1.Node, error) {
 	if kl.kubeClient != nil {
-		if n, err := kl.nodeLister.Get(string(kl.nodeName)); err == nil {
+		if n, err := kl.GetNode(); err == nil {
 			return n, nil
 		}
 	}
diff --git a/pkg/kubelet/kubelet_test.go b/pkg/kubelet/kubelet_test.go
index 785515f7c8c..c0decccfa31 100644
--- a/pkg/kubelet/kubelet_test.go
+++ b/pkg/kubelet/kubelet_test.go
@@ -182,6 +182,7 @@ func newTestKubeletWithImageList(
 	kubelet.masterServiceNamespace = metav1.NamespaceDefault
 	kubelet.serviceLister = testServiceLister{}
 	kubelet.serviceHasSynced = func() bool { return true }
+	kubelet.nodeHasSynced = func() bool { return true }
 	kubelet.nodeLister = testNodeLister{
 		nodes: []*v1.Node{
 			{