cluster-api: node template in scale-from-0-nodes scenario with DRA

Modify TemplateNodeInfo() to return the template of ResourceSlice.
This is to address the DRA expansion of Cluster Autoscaler, allowing users to set the number of GPUs and DRA driver name by specifying
the annotation to NodeGroup provided by cluster-api.

Signed-off-by: Tsubasa Watanabe <[email protected]>

cluster-autoscaler/cloudprovider/clusterapi/clusterapi_nodegroup.go

@@ -283,7 +283,12 @@ func (ng *nodegroup) TemplateNodeInfo() (*framework.NodeInfo, error) {
 		return nil, err
 	}
 
-	nodeInfo := framework.NewNodeInfo(&node, nil, &framework.PodInfo{Pod: cloudprovider.BuildKubeProxy(ng.scalableResource.Name())})
+	resourceSlices, err := ng.scalableResource.InstanceResourceSlices(nodeName)
+	if err != nil {
+		return nil, err
+	}
+
+	nodeInfo := framework.NewNodeInfo(&node, resourceSlices, &framework.PodInfo{Pod: cloudprovider.BuildKubeProxy(ng.scalableResource.Name())})
 	return nodeInfo, nil
 }
 

cluster-autoscaler/cloudprovider/clusterapi/clusterapi_unstructured.go

@@ -20,18 +20,21 @@ import (
 	"context"
 	"fmt"
 	"path"
+	"strconv"
 	"strings"
 	"time"
 
 	"github.com/pkg/errors"
 	apiv1 "k8s.io/api/core/v1"
 	corev1 "k8s.io/api/core/v1"
+	resourceapi "k8s.io/api/resource/v1beta1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/validation"
 	klog "k8s.io/klog/v2"
+	"k8s.io/utils/ptr"
 )
 
 type unstructuredScalableResource struct {
@@ -297,6 +300,46 @@ func (r unstructuredScalableResource) InstanceCapacity() (map[corev1.ResourceNam
 	return capacity, nil
 }
 
+func (r unstructuredScalableResource) InstanceResourceSlices(nodeName string) ([]*resourceapi.ResourceSlice, error) {
+	driver := r.InstanceDRADriver()
+	gpuCount, err := r.InstanceGPUCapacityAnnotation()
+	if err != nil {
+		return nil, err
+	}
+
+	var result []*resourceapi.ResourceSlice
+	if driver != "" && !gpuCount.IsZero() {
+		resourceslice := &resourceapi.ResourceSlice{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: nodeName + "-" + driver,
+			},
+			Spec: resourceapi.ResourceSliceSpec{
+				Driver:   driver,
+				NodeName: nodeName,
+				Pool: resourceapi.ResourcePool{
+					Name: nodeName,
+				},
+			},
+		}
+		for i := 0; i < int(gpuCount.Value()); i++ {
+			device := resourceapi.Device{
+				Name: "gpu-" + strconv.Itoa(i),
+				Basic: &resourceapi.BasicDevice{
+					Attributes: map[resourceapi.QualifiedName]resourceapi.DeviceAttribute{
+						"type": {
+							StringValue: ptr.To(GpuDeviceType),
+						},
+					},
+				},
+			}
+			resourceslice.Spec.Devices = append(resourceslice.Spec.Devices, device)
+		}
+		result = append(result, resourceslice)
+		return result, nil
+	}
+	return nil, nil
+}
+
 func (r unstructuredScalableResource) InstanceEphemeralDiskCapacityAnnotation() (resource.Quantity, error) {
 	return parseEphemeralDiskCapacity(r.unstructured.GetAnnotations())
 }
@@ -321,6 +364,10 @@ func (r unstructuredScalableResource) InstanceMaxPodsCapacityAnnotation() (resou
 	return parseMaxPodsCapacity(r.unstructured.GetAnnotations())
 }
 
+func (r unstructuredScalableResource) InstanceDRADriver() string {
+	return parseDRADriver(r.unstructured.GetAnnotations())
+}
+
 func (r unstructuredScalableResource) readInfrastructureReferenceResource() (*unstructured.Unstructured, error) {
 	infraref, found, err := unstructured.NestedStringMap(r.unstructured.Object, "spec", "template", "spec", "infrastructureRef")
 	if !found || err != nil {

cluster-autoscaler/cloudprovider/clusterapi/clusterapi_utils.go

@@ -40,6 +40,7 @@ const (
 	maxPodsKey      = "capacity.cluster-autoscaler.kubernetes.io/maxPods"
 	taintsKey       = "capacity.cluster-autoscaler.kubernetes.io/taints"
 	labelsKey       = "capacity.cluster-autoscaler.kubernetes.io/labels"
+	draDriverKey    = "capacity.cluster-autoscaler.kubernetes.io/dra-driver"
 	// UnknownArch is used if the Architecture is Unknown
 	UnknownArch SystemArchitecture = ""
 	// Amd64 is used if the Architecture is x86_64
@@ -54,6 +55,8 @@ const (
 	DefaultArch = Amd64
 	// scaleUpFromZeroDefaultEnvVar is the name of the env var for the default architecture
 	scaleUpFromZeroDefaultArchEnvVar = "CAPI_SCALE_ZERO_DEFAULT_ARCH"
+	// gpuDeviceType is used if DRA device is GPU
+	GpuDeviceType = "gpu"
 )
 
 var (
@@ -282,6 +285,13 @@ func parseMaxPodsCapacity(annotations map[string]string) (resource.Quantity, err
 	return parseIntKey(annotations, maxPodsKey)
 }
 
+func parseDRADriver(annotations map[string]string) string {
+	if val, found := annotations[draDriverKey]; found {
+		return val
+	}
+	return ""
+}
+
 func clusterNameFromResource(r *unstructured.Unstructured) string {
 	// Use Spec.ClusterName if defined (only available on v1alpha3+ types)
 	clusterName, found, err := unstructured.NestedString(r.Object, "spec", "clusterName")