Adding check to backfill loop to confirm cloud provider node no longe…

…r exists before flagging the node as deleted. Modifying some comments to be more accurate. Replacing erroneous line deletion.

cluster-autoscaler/clusterstate/clusterstate.go

@@ -298,6 +298,7 @@ func (csr *ClusterStateRegistry) UpdateNodes(nodes []*apiv1.Node, nodeInfosForGr
 		return err
 	}
 	notRegistered := getNotRegisteredNodes(nodes, cloudProviderNodeInstances, currentTime)
+
 	csr.Lock()
 	defer csr.Unlock()
 
@@ -1000,19 +1001,22 @@ func (csr *ClusterStateRegistry) getCloudProviderDeletedNodes(allNodes []*apiv1.
 
 	// Fill previously deleted nodes, if they are still registered in Kubernetes
 	for nodeName, node := range csr.deletedNodes {
-		if _, found := registeredNodes[nodeName]; found {
+		// Safety check to prevent flagging Kubernetes nodes as deleted
+		// if the Cloud Provider instance is re-discovered
+		_, cloudProviderFound := currentCloudInstances[node.Name]
+		if _, found := registeredNodes[nodeName]; found && !cloudProviderFound {
 			nodesRemoved = append(nodesRemoved, node)
 		}
 	}
 
 	// Seek nodes that may have been deleted since last update
 	// cloudProviderNodeInstances are retrieved by nodeGroup,
-	// not autoscaled nodes will not be included
+	// not autoscaled nodes will be excluded
 	for _, instances := range csr.cloudProviderNodeInstances {
 		for _, instance := range instances {
 			if _, found := currentCloudInstances[instance.Id]; !found {
-				// Check for reference to deleted cloud provider instances by
-				// all registered Kubernetes node names
+				// Check Kubernetes registered nodes for corresponding deleted
+				// Cloud Provider instance
 				if kubeNode, kubeNodeFound := registeredNodes[instance.Id]; kubeNodeFound {
 					nodesRemoved = append(nodesRemoved, kubeNode)
 				}