Communicate the result of RemoveUnneededNodeGroups to ScaleDownStatusProcessor

cluster-autoscaler/core/scale_test_common.go

@@ -129,10 +129,11 @@ func (p *mockAutoprovisioningNodeGroupManager) CreateNodeGroup(context *context.
 	return result, nil
 }
 
-func (p *mockAutoprovisioningNodeGroupManager) RemoveUnneededNodeGroups(context *context.AutoscalingContext) error {
+func (p *mockAutoprovisioningNodeGroupManager) RemoveUnneededNodeGroups(context *context.AutoscalingContext) (removedNodeGroups []cloudprovider.NodeGroup, err error) {
 	if !context.AutoscalingOptions.NodeAutoprovisioningEnabled {
-		return nil
+		return nil, nil
 	}
+	removedNodeGroups = make([]cloudprovider.NodeGroup, 0)
 	nodeGroups := context.CloudProvider.NodeGroups()
 	for _, nodeGroup := range nodeGroups {
 		if !nodeGroup.Autoprovisioned() {
@@ -150,8 +151,9 @@ func (p *mockAutoprovisioningNodeGroupManager) RemoveUnneededNodeGroups(context
 		}
 		err = nodeGroup.Delete()
 		assert.NoError(p.t, err)
+		removedNodeGroups = append(removedNodeGroups, nodeGroup)
 	}
-	return nil
+	return removedNodeGroups, nil
 }
 
 func (p *mockAutoprovisioningNodeGroupManager) CleanUp() {

cluster-autoscaler/core/static_autoscaler.go

@@ -418,13 +418,18 @@ func (a *StaticAutoscaler) RunOnce(currentTime time.Time) errors.AutoscalerError
 
 			// We want to delete unneeded Node Groups only if there was no recent scale up,
 			// and there is no current delete in progress and there was no recent errors.
-			a.processors.NodeGroupManager.RemoveUnneededNodeGroups(autoscalingContext)
+			removedNodeGroups, err := a.processors.NodeGroupManager.RemoveUnneededNodeGroups(autoscalingContext)
+			if err != nil {
+				klog.Errorf("Error while removing unneeded node groups: %v", err)
+			}
 
 			scaleDownStart := time.Now()
 			metrics.UpdateLastTime(metrics.ScaleDown, scaleDownStart)
 			scaleDownStatus, typedErr := scaleDown.TryToScaleDown(allNodes, originalScheduledPods, pdbs, currentTime)
 			metrics.UpdateDurationFromStart(metrics.ScaleDown, scaleDownStart)
 
+			scaleDownStatus.RemovedNodeGroups = removedNodeGroups
+
 			if scaleDownStatus.Result == status.ScaleDownNodeDeleted {
 				a.lastScaleDownDeleteTime = currentTime
 				a.clusterStateRegistry.Recalculate()

cluster-autoscaler/processors/nodegroups/nodegroup_manager.go

@@ -25,7 +25,7 @@ import (
 // NodeGroupManager is responsible for creating/deleting node groups.
 type NodeGroupManager interface {
 	CreateNodeGroup(context *context.AutoscalingContext, nodeGroup cloudprovider.NodeGroup) (CreateNodeGroupResult, errors.AutoscalerError)
-	RemoveUnneededNodeGroups(context *context.AutoscalingContext) error
+	RemoveUnneededNodeGroups(context *context.AutoscalingContext) (removedNodeGroups []cloudprovider.NodeGroup, err error)
 	CleanUp()
 }
 
@@ -52,8 +52,8 @@ func (*NoOpNodeGroupManager) CreateNodeGroup(context *context.AutoscalingContext
 }
 
 // RemoveUnneededNodeGroups does nothing in NoOpNodeGroupManager
-func (*NoOpNodeGroupManager) RemoveUnneededNodeGroups(context *context.AutoscalingContext) error {
-	return nil
+func (*NoOpNodeGroupManager) RemoveUnneededNodeGroups(context *context.AutoscalingContext) (removedNodeGroups []cloudprovider.NodeGroup, err error) {
+	return nil, nil
 }
 
 // CleanUp does nothing in NoOpNodeGroupManager

cluster-autoscaler/processors/status/scale_down_status_processor.go

@@ -27,6 +27,7 @@ import (
 type ScaleDownStatus struct {
 	Result            ScaleDownResult
 	ScaledDownNodes   []*ScaleDownNode
+	RemovedNodeGroups []cloudprovider.NodeGroup
 	NodeDeleteResults map[string]NodeDeleteResult
 }