fix: substract scratch volumes from MaxVolumesPerNode (#78)

Author: Tomy2e

pkg/driver/helpers.go

@@ -9,14 +9,15 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"slices"
 	"strconv"
 	"strings"
 
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"github.com/scaleway/scaleway-csi/pkg/scaleway"
 	block "github.com/scaleway/scaleway-sdk-go/api/block/v1"
+	"github.com/scaleway/scaleway-sdk-go/api/instance/v1"
 	"github.com/scaleway/scaleway-sdk-go/scw"
-	"golang.org/x/exp/slices"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/timestamppb"
@@ -520,3 +521,29 @@ func uint64ToInt64(v uint64) int64 {
 
 	return int64(v)
 }
+
+// attachedScratchVolumes returns the number of attached scratch volumes, based
+// on the instance metadata.
+func attachedScratchVolumes(md *instance.Metadata) int {
+	var count int
+
+	for _, vol := range md.Volumes {
+		if vol.VolumeType == "scratch" {
+			count++
+		}
+	}
+
+	return count
+}
+
+// maxVolumesPerNode returns the maximum number of volumes that can be attached to a node,
+// after substracting the system root volume and the provided number of reserved volumes.
+// It returns an error if the result is 0 or less.
+func maxVolumesPerNode(reservedCount int) (int64, error) {
+	max := scaleway.MaxVolumesPerNode - reservedCount - 1
+	if max <= 0 {
+		return 0, fmt.Errorf("max number of volumes that can be attached to this node must be at least 1, currently is %d", max)
+	}
+
+	return int64(max), nil
+}

pkg/driver/node.go

@@ -25,8 +25,9 @@ type nodeService struct {
 
 	diskUtils DiskUtils
 
-	nodeID   string
-	nodeZone scw.Zone
+	nodeID            string
+	nodeZone          scw.Zone
+	maxVolumesPerNode int64
 }
 
 func newNodeService() (*nodeService, error) {
@@ -40,10 +41,16 @@ func newNodeService() (*nodeService, error) {
 		return nil, fmt.Errorf("invalid zone in metadata: %w", err)
 	}
 
+	maxVolumesPerNode, err := maxVolumesPerNode(attachedScratchVolumes(metadata))
+	if err != nil {
+		return nil, err
+	}
+
 	return &nodeService{
-		diskUtils: newDiskUtils(),
-		nodeID:    metadata.ID,
-		nodeZone:  zone,
+		diskUtils:         newDiskUtils(),
+		nodeID:            metadata.ID,
+		nodeZone:          zone,
+		maxVolumesPerNode: maxVolumesPerNode,
 	}, nil
 }
 
@@ -431,7 +438,7 @@ func (d *nodeService) NodeGetCapabilities(ctx context.Context, req *csi.NodeGetC
 func (d *nodeService) NodeGetInfo(ctx context.Context, req *csi.NodeGetInfoRequest) (*csi.NodeGetInfoResponse, error) {
 	return &csi.NodeGetInfoResponse{
 		NodeId:            d.nodeZone.String() + "/" + d.nodeID,
-		MaxVolumesPerNode: scaleway.MaxVolumesPerNode - 1, // One is already used by the l_ssd or b_ssd root volume
+		MaxVolumesPerNode: d.maxVolumesPerNode,
 		AccessibleTopology: &csi.Topology{
 			Segments: map[string]string{
 				ZoneTopologyKey: d.nodeZone.String(),