Rename the autoscaling option

* Renamed the "AtomicScaling" autoscaling option to
  "ZeroOrMaxNodeScaling" to be more clear about the behavior.

cluster-autoscaler/cloudprovider/test/test_cloud_provider.go

@@ -443,7 +443,7 @@ func (tng *TestNodeGroup) DeleteNodes(nodes []*apiv1.Node) error {
 	id := tng.id
 	tng.targetSize -= len(nodes)
 	tng.Unlock()
-	if tng.opts != nil && tng.opts.AtomicScaling && tng.targetSize != 0 {
+	if tng.opts != nil && tng.opts.ZeroOrMaxNodeScaling && tng.targetSize != 0 {
 		return fmt.Errorf("TestNodeGroup: attempted to partially scale down a node group that should be scaled down atomically")
 	}
 	for _, node := range nodes {

cluster-autoscaler/config/autoscaling_options.go

@@ -46,8 +46,8 @@ type NodeGroupAutoscalingOptions struct {
 	ScaleDownUnreadyTime time.Duration
 	// Maximum time CA waits for node to be provisioned
 	MaxNodeProvisionTime time.Duration
-	// AtomicScaling means that a node group should be scaled up or down all at once instead of one-by-one
-	AtomicScaling bool
+	// ZeroOrMaxNodeScaling means that a node group should be scaled up to maximum size or down to zero nodes all at once instead of one-by-one.
+	ZeroOrMaxNodeScaling bool
 }
 
 // GCEOptions contain autoscaling options specific to GCE cloud provider.

cluster-autoscaler/core/scaledown/actuation/actuator_test.go

@@ -1103,7 +1103,7 @@ func TestStartDeletionInBatchBasic(t *testing.T) {
 func sizedNodeGroup(id string, size int, atomic bool) cloudprovider.NodeGroup {
 	ng := testprovider.NewTestNodeGroup(id, 10000, 0, size, true, false, "n1-standard-2", nil, nil)
 	ng.SetOptions(&config.NodeGroupAutoscalingOptions{
-		AtomicScaling: atomic,
+		ZeroOrMaxNodeScaling: atomic,
 	})
 	return ng
 }

cluster-autoscaler/core/scaledown/actuation/group_deletion_scheduler.go

@@ -79,7 +79,7 @@ func (ds *GroupDeletionScheduler) ScheduleDeletion(nodeInfo *framework.NodeInfo,
 		return
 	}
 
-	ds.addToBatcher(nodeInfo, nodeGroup, batchSize, drain, opts.AtomicScaling)
+	ds.addToBatcher(nodeInfo, nodeGroup, batchSize, drain, opts.ZeroOrMaxNodeScaling)
 }
 
 // prepareNodeForDeletion is a long-running operation, so it needs to avoid locking the AtomicDeletionScheduler object

cluster-autoscaler/core/scaledown/budgets/budgets.go

@@ -173,7 +173,7 @@ func (bp *ScaleDownBudgetProcessor) categorize(groups []*NodeGroupView) (individ
 			klog.Errorf("Failed to get autoscaling options for node group %s: %v", view.Group.Id(), err)
 			continue
 		}
-		if autoscalingOptions != nil && autoscalingOptions.AtomicScaling {
+		if autoscalingOptions != nil && autoscalingOptions.ZeroOrMaxNodeScaling {
 			atomic = append(atomic, view)
 		} else {
 			individual = append(individual, view)
@@ -196,7 +196,7 @@ func (bp *ScaleDownBudgetProcessor) groupByNodeGroup(nodes []*apiv1.Node) (indiv
 			klog.Errorf("Failed to get autoscaling options for node group %s: %v", nodeGroup.Id(), err)
 			continue
 		}
-		if autoscalingOptions != nil && autoscalingOptions.AtomicScaling {
+		if autoscalingOptions != nil && autoscalingOptions.ZeroOrMaxNodeScaling {
 			if idx, ok := atomicGroup[nodeGroup]; ok {
 				atomic[idx].Nodes = append(atomic[idx].Nodes, node)
 			} else {

cluster-autoscaler/core/scaledown/budgets/budgets_test.go

@@ -361,7 +361,7 @@ var transformNodeGroupView = cmp.Transformer("transformNodeGroupView", func(b No
 func sizedNodeGroup(id string, size int, atomic bool) cloudprovider.NodeGroup {
 	ng := testprovider.NewTestNodeGroup(id, 10000, 0, size, true, false, "n1-standard-2", nil, nil)
 	ng.SetOptions(&config.NodeGroupAutoscalingOptions{
-		AtomicScaling: atomic,
+		ZeroOrMaxNodeScaling: atomic,
 	})
 	return ng
 }

cluster-autoscaler/core/scaledown/planner/planner_test.go

@@ -795,7 +795,7 @@ func TestNodesToDelete(t *testing.T) {
 func sizedNodeGroup(id string, size int, atomic bool) cloudprovider.NodeGroup {
 	ng := testprovider.NewTestNodeGroup(id, 10000, 0, size, true, false, "n1-standard-2", nil, nil)
 	ng.SetOptions(&config.NodeGroupAutoscalingOptions{
-		AtomicScaling: atomic,
+		ZeroOrMaxNodeScaling: atomic,
 	})
 	return ng
 }

cluster-autoscaler/core/scaleup/orchestrator/orchestrator.go

@@ -446,7 +446,7 @@ func (o *ScaleUpOrchestrator) filterValidScaleUpNodeGroups(
 			klog.Errorf("Couldn't get autoscaling options for ng: %v", nodeGroup.Id())
 		}
 		numNodes := 1
-		if autoscalingOptions != nil && autoscalingOptions.AtomicScaling {
+		if autoscalingOptions != nil && autoscalingOptions.ZeroOrMaxNodeScaling {
 			numNodes = nodeGroup.MaxSize() - currentTargetSize
 			if o.autoscalingContext.MaxNodesTotal != 0 && currentNodeCount+numNodes > o.autoscalingContext.MaxNodesTotal {
 				klog.V(4).Infof("Skipping node group %s - atomic scale-up exceeds cluster node count limit", nodeGroup.Id())
@@ -495,7 +495,7 @@ func (o *ScaleUpOrchestrator) ComputeExpansionOption(
 	if err != nil {
 		klog.Errorf("Failed to get autoscaling options for node group %s: %v", nodeGroup.Id(), err)
 	}
-	if autoscalingOptions != nil && autoscalingOptions.AtomicScaling {
+	if autoscalingOptions != nil && autoscalingOptions.ZeroOrMaxNodeScaling {
 		if option.NodeCount > 0 && option.NodeCount != nodeGroup.MaxSize() {
 			option.NodeCount = nodeGroup.MaxSize()
 		}
@@ -633,7 +633,7 @@ func (o *ScaleUpOrchestrator) ComputeSimilarNodeGroups(
 	if err != nil {
 		klog.Errorf("Failed to get autoscaling options for node group %s: %v", nodeGroup.Id(), err)
 	}
-	if autoscalingOptions != nil && autoscalingOptions.AtomicScaling {
+	if autoscalingOptions != nil && autoscalingOptions.ZeroOrMaxNodeScaling {
 		return nil
 	}
 

cluster-autoscaler/core/scaleup/orchestrator/orchestrator_test.go

@@ -124,9 +124,9 @@ func TestMixedScaleUp(t *testing.T) {
 	simpleScaleUpTest(t, config, expectedResults)
 }
 
-func TestAtomicScaleUp(t *testing.T) {
+func TestZeroOrMaxNodeScaling(t *testing.T) {
 	options := defaultOptions
-	options.NodeGroupDefaults.AtomicScaling = true
+	options.NodeGroupDefaults.ZeroOrMaxNodeScaling = true
 
 	optionsWithLimitedMaxCores := options
 	optionsWithLimitedMaxCores.MaxCoresTotal = 3

cluster-autoscaler/processors/nodes/post_filtering_processor.go

@@ -59,7 +59,7 @@ func (p *PostFilteringScaleDownNodeProcessor) filterOutIncompleteAtomicNodeGroup
 			klog.Errorf("Failed to get autoscaling options for node group %s: %v", nodeGroup.Id(), err)
 			continue
 		}
-		if autoscalingOptions != nil && autoscalingOptions.AtomicScaling {
+		if autoscalingOptions != nil && autoscalingOptions.ZeroOrMaxNodeScaling {
 			klog.V(2).Infof("Considering node %s for atomic scale down", node.Node.Name)
 			nodesByGroup[nodeGroup] = append(nodesByGroup[nodeGroup], node)
 		} else {