kubelet: Refactor tryUpdateNodeStatus() into smaller functions

pkg/kubelet/kubelet_node_status.go

@@ -478,21 +478,39 @@ func (kl *Kubelet) tryUpdateNodeStatus(tryNumber int) error {
 	if tryNumber == 0 {
 		util.FromApiserverCache(&opts)
 	}
-	node, err := kl.heartbeatClient.CoreV1().Nodes().Get(context.TODO(), string(kl.nodeName), opts)
+	originalNode, err := kl.heartbeatClient.CoreV1().Nodes().Get(context.TODO(), string(kl.nodeName), opts)
 	if err != nil {
 		return fmt.Errorf("error getting node %q: %v", kl.nodeName, err)
 	}
-
-	originalNode := node.DeepCopy()
 	if originalNode == nil {
 		return fmt.Errorf("nil %q node object", kl.nodeName)
 	}
 
+	node, changed := kl.updateNode(originalNode)
+
+	if kl.clock.Since(kl.lastStatusReportTime) < kl.nodeStatusReportFrequency && !changed {
+		kl.markVolumesFromNode(node)
+		return nil
+	}
+
+	updatedNode, err := kl.patchNodeStatus(originalNode, node)
+	if err == nil {
+		kl.markVolumesFromNode(updatedNode)
+	}
+	return err
+}
+
+// updateNode creates a copy of originalNode and runs update logic on it.
+// It returns the updated node object and a bool indicating if anything has been changed.
+func (kl *Kubelet) updateNode(originalNode *v1.Node) (*v1.Node, bool) {
+	node := originalNode.DeepCopy()
+
 	podCIDRChanged := false
 	if len(node.Spec.PodCIDRs) != 0 {
 		// Pod CIDR could have been updated before, so we cannot rely on
 		// node.Spec.PodCIDR being non-empty. We also need to know if pod CIDR is
 		// actually changed.
+		var err error
 		podCIDRs := strings.Join(node.Spec.PodCIDRs, ",")
 		if podCIDRChanged, err = kl.updatePodCIDR(podCIDRs); err != nil {
 			klog.ErrorS(err, "Error updating pod CIDR")
@@ -520,41 +538,47 @@ func (kl *Kubelet) tryUpdateNodeStatus(tryNumber int) error {
 
 	kl.setNodeStatus(node)
 
-	now := kl.clock.Now()
-	if now.Before(kl.lastStatusReportTime.Add(kl.nodeStatusReportFrequency)) {
-		if !podCIDRChanged && !nodeStatusHasChanged(&originalNode.Status, &node.Status) && !areRequiredLabelsNotPresent {
-			// We must mark the volumes as ReportedInUse in volume manager's dsw even
-			// if no changes were made to the node status (no volumes were added or removed
-			// from the VolumesInUse list).
-			//
-			// The reason is that on a kubelet restart, the volume manager's dsw is
-			// repopulated and the volume ReportedInUse is initialized to false, while the
-			// VolumesInUse list from the Node object still contains the state from the
-			// previous kubelet instantiation.
-			//
-			// Once the volumes are added to the dsw, the ReportedInUse field needs to be
-			// synced from the VolumesInUse list in the Node.Status.
-			//
-			// The MarkVolumesAsReportedInUse() call cannot be performed in dsw directly
-			// because it does not have access to the Node object.
-			// This also cannot be populated on node status manager init because the volume
-			// may not have been added to dsw at that time.
-			kl.volumeManager.MarkVolumesAsReportedInUse(node.Status.VolumesInUse)
-			return nil
-		}
-	}
+	return node, podCIDRChanged || nodeStatusHasChanged(&originalNode.Status, &node.Status) || areRequiredLabelsNotPresent
+}
 
+// patchNodeStatus patches node on the API server based on originalNode.
+// It returns any potential error, or an updatedNode and refreshes the state of kubelet when successful.
+func (kl *Kubelet) patchNodeStatus(originalNode, node *v1.Node) (*v1.Node, error) {
 	// Patch the current status on the API server
 	updatedNode, _, err := nodeutil.PatchNodeStatus(kl.heartbeatClient.CoreV1(), types.NodeName(kl.nodeName), originalNode, node)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	kl.lastStatusReportTime = now
+	kl.lastStatusReportTime = kl.clock.Now()
 	kl.setLastObservedNodeAddresses(updatedNode.Status.Addresses)
-	// If update finishes successfully, mark the volumeInUse as reportedInUse to indicate
-	// those volumes are already updated in the node's status
-	kl.volumeManager.MarkVolumesAsReportedInUse(updatedNode.Status.VolumesInUse)
-	return nil
+	return updatedNode, nil
+}
+
+// markVolumesFromNode updates volumeManager with VolumesInUse status from node.
+//
+// In the case of node status update being unnecessary, call with the fetched node.
+// We must mark the volumes as ReportedInUse in volume manager's dsw even
+// if no changes were made to the node status (no volumes were added or removed
+// from the VolumesInUse list).
+//
+// The reason is that on a kubelet restart, the volume manager's dsw is
+// repopulated and the volume ReportedInUse is initialized to false, while the
+// VolumesInUse list from the Node object still contains the state from the
+// previous kubelet instantiation.
+//
+// Once the volumes are added to the dsw, the ReportedInUse field needs to be
+// synced from the VolumesInUse list in the Node.Status.
+//
+// The MarkVolumesAsReportedInUse() call cannot be performed in dsw directly
+// because it does not have access to the Node object.
+// This also cannot be populated on node status manager init because the volume
+// may not have been added to dsw at that time.
+//
+// Or, after a successful node status update, call with updatedNode returned from
+// the patch call, to mark the volumeInUse as reportedInUse to indicate
+// those volumes are already updated in the node's status
+func (kl *Kubelet) markVolumesFromNode(node *v1.Node) {
+	kl.volumeManager.MarkVolumesAsReportedInUse(node.Status.VolumesInUse)
 }
 
 // recordNodeStatusEvent records an event of the given type with the given