Add ReadWriteMany (RWX) volume support via NFS

cmd/api/api/volumes.go

@@ -46,11 +46,31 @@ func (s *ApiService) CreateVolume(ctx context.Context, request oapi.CreateVolume
 		}, nil
 	}
 
+	var accessMode volumes.AccessMode
+	if request.Body.AccessMode != nil {
+		accessMode = volumes.AccessMode(*request.Body.AccessMode)
+	}
+	var nfsConfig *volumes.NFSConfig
+	if request.Body.Nfs != nil {
+		nfsConfig = &volumes.NFSConfig{
+			Server:     request.Body.Nfs.Server,
+			ExportPath: request.Body.Nfs.ExportPath,
+		}
+		if request.Body.Nfs.Version != nil {
+			nfsConfig.Version = *request.Body.Nfs.Version
+		}
+		if request.Body.Nfs.Options != nil {
+			nfsConfig.Options = *request.Body.Nfs.Options
+		}
+	}
+
 	domainReq := volumes.CreateVolumeRequest{
-		Name:   request.Body.Name,
-		SizeGb: request.Body.SizeGb,
-		Id:     request.Body.Id,
-		Tags:   toMapTags(request.Body.Tags),
+		Name:       request.Body.Name,
+		SizeGb:     request.Body.SizeGb,
+		AccessMode: accessMode,
+		NFS:        nfsConfig,
+		Id:         request.Body.Id,
+		Tags:       toMapTags(request.Body.Tags),
 	}
 
 	vol, err := s.VolumeManager.CreateVolume(ctx, domainReq)
@@ -61,7 +81,7 @@ func (s *ApiService) CreateVolume(ctx context.Context, request oapi.CreateVolume
 				Message: "volume with this ID already exists",
 			}, nil
 		}
-		if errors.Is(err, tags.ErrInvalidTags) {
+		if errors.Is(err, tags.ErrInvalidTags) || errors.Is(err, volumes.ErrInvalidRequest) {
 			return oapi.CreateVolume400JSONResponse{
 				Code:    "invalid_request",
 				Message: err.Error(),
@@ -182,12 +202,28 @@ func (s *ApiService) DeleteVolume(ctx context.Context, request oapi.DeleteVolume
 }
 
 func volumeToOAPI(vol volumes.Volume) oapi.Volume {
+	accessMode := oapi.VolumeAccessMode(vol.AccessMode)
 	oapiVol := oapi.Volume{
-		Id:        vol.Id,
-		Name:      vol.Name,
-		SizeGb:    vol.SizeGb,
-		Tags:      toOAPITags(vol.Tags),
-		CreatedAt: vol.CreatedAt,
+		Id:         vol.Id,
+		Name:       vol.Name,
+		SizeGb:     vol.SizeGb,
+		AccessMode: &accessMode,
+		Tags:       toOAPITags(vol.Tags),
+		CreatedAt:  vol.CreatedAt,
+	}
+
+	if vol.NFS != nil {
+		nfs := &oapi.NFSConfig{
+			Server:     vol.NFS.Server,
+			ExportPath: vol.NFS.ExportPath,
+		}
+		if vol.NFS.Version != "" {
+			nfs.Version = &vol.NFS.Version
+		}
+		if vol.NFS.Options != "" {
+			nfs.Options = &vol.NFS.Options
+		}
+		oapiVol.Nfs = nfs
 	}
 
 	// Convert attachments

lib/instances/admission.go

@@ -3,7 +3,7 @@ package instances
 func volumeOverlayReservationBytes(volumes []VolumeAttachment) int64 {
 	var total int64
 	for _, vol := range volumes {
-		if vol.Overlay {
+		if vol.Overlay && vol.NFS == nil {
 			total += vol.OverlaySize
 		}
 	}

lib/instances/configdisk.go

@@ -98,9 +98,28 @@ func (m *manager) buildGuestConfig(ctx context.Context, inst *Instance, imageInf
 	}
 
 	// Volume mounts
-	// Volumes are attached as /dev/vdd, /dev/vde, etc. (after vda=rootfs, vdb=overlay, vdc=config)
+	// Block volumes are attached as /dev/vdd, /dev/vde, etc. (after vda=rootfs, vdb=overlay, vdc=config)
+	// NFS volumes don't consume a block device — they're mounted via the network.
 	deviceIdx := 0
 	for _, vol := range inst.Volumes {
+		if vol.NFS != nil {
+			// NFS-backed volume (ReadWriteMany) — no block device, guest mounts via NFS
+			mount := vmconfig.VolumeMount{
+				Path:          vol.MountPath,
+				Mode:          "nfs",
+				NFSServer:     vol.NFS.Server,
+				NFSExportPath: vol.NFS.ExportPath,
+				NFSVersion:    vol.NFS.Version,
+				NFSOptions:    vol.NFS.Options,
+			}
+			if vol.Readonly {
+				mount.Mode = "nfs_ro"
+			}
+			cfg.VolumeMounts = append(cfg.VolumeMounts, mount)
+			continue
+		}
+
+		// Block-backed volume
 		device := fmt.Sprintf("/dev/vd%c", 'd'+deviceIdx)
 		mount := vmconfig.VolumeMount{
 			Device: device,

lib/instances/create.go

@@ -420,14 +420,31 @@ func (m *manager) createInstance(
 	// 15. Validate and attach volumes
 	if len(req.Volumes) > 0 {
 		log.DebugContext(ctx, "validating volumes", "instance_id", id, "count", len(req.Volumes))
-		for _, volAttach := range req.Volumes {
-			// Check volume exists
-			_, err := m.volumeManager.GetVolume(ctx, volAttach.VolumeID)
+		resolvedVolumes := make([]VolumeAttachment, len(req.Volumes))
+		for i, volAttach := range req.Volumes {
+			// Check volume exists and get its details
+			vol, err := m.volumeManager.GetVolume(ctx, volAttach.VolumeID)
 			if err != nil {
 				log.ErrorContext(ctx, "volume not found", "instance_id", id, "volume_id", volAttach.VolumeID, "error", err)
 				return nil, fmt.Errorf("volume %s: %w", volAttach.VolumeID, err)
 			}
 
+			resolvedVolumes[i] = volAttach
+
+			// Populate NFS config from the volume for RWX volumes
+			if vol.NFS != nil {
+				resolvedVolumes[i].NFS = &VolumeNFSConfig{
+					Server:     vol.NFS.Server,
+					ExportPath: vol.NFS.ExportPath,
+					Version:    vol.NFS.Version,
+					Options:    vol.NFS.Options,
+				}
+				// NFS volumes require networking for NFS client access
+				if !req.NetworkEnabled {
+					return nil, fmt.Errorf("volume %s: NFS volumes require network.enabled=true", volAttach.VolumeID)
+				}
+			}
+
 			// Mark volume as attached (AttachVolume handles multi-attach validation)
 			if err := m.volumeManager.AttachVolume(ctx, volAttach.VolumeID, volumes.AttachVolumeRequest{
 				InstanceID: id,
@@ -444,7 +461,7 @@ func (m *manager) createInstance(
 				m.volumeManager.DetachVolume(ctx, volumeID, id)
 			})
 
-			// Create overlay disk for volumes with overlay enabled
+			// Create overlay disk for volumes with overlay enabled (not for NFS)
 			if volAttach.Overlay {
 				log.DebugContext(ctx, "creating volume overlay disk", "instance_id", id, "volume_id", volAttach.VolumeID, "size", volAttach.OverlaySize)
 				if err := m.createVolumeOverlayDisk(id, volAttach.VolumeID, volAttach.OverlaySize); err != nil {
@@ -453,8 +470,12 @@ func (m *manager) createInstance(
 				}
 			}
 		}
-		// Store volume attachments in metadata
-		stored.Volumes = req.Volumes
+		// Re-validate with NFS info populated
+		if err := validateVolumeAttachments(resolvedVolumes); err != nil {
+			return nil, fmt.Errorf("%w: %v", ErrInvalidRequest, err)
+		}
+		// Store resolved volume attachments in metadata
+		stored.Volumes = resolvedVolumes
 	}
 
 	// 16. Create config disk (needs Instance for buildVMConfig)
@@ -614,10 +635,13 @@ func validateCreateRequest(req *CreateInstanceRequest) error {
 }
 
 // validateVolumeAttachments validates volume attachment requests
-func validateVolumeAttachments(volumes []VolumeAttachment) error {
-	// Count total devices needed (each overlay volume needs 2 devices: base + overlay)
+func validateVolumeAttachments(vols []VolumeAttachment) error {
+	// Count total block devices needed (NFS volumes don't consume a device)
 	totalDevices := 0
-	for _, vol := range volumes {
+	for _, vol := range vols {
+		if vol.NFS != nil {
+			continue // NFS volumes don't use block devices
+		}
 		totalDevices++
 		if vol.Overlay {
 			totalDevices++ // Overlay needs an additional device
@@ -628,7 +652,7 @@ func validateVolumeAttachments(volumes []VolumeAttachment) error {
 	}
 
 	seenPaths := make(map[string]bool)
-	for _, vol := range volumes {
+	for _, vol := range vols {
 		// Validate mount path is absolute
 		if !filepath.IsAbs(vol.MountPath) {
 			return fmt.Errorf("volume %s: mount path %q must be absolute", vol.VolumeID, vol.MountPath)
@@ -648,6 +672,11 @@ func validateVolumeAttachments(volumes []VolumeAttachment) error {
 		}
 		seenPaths[cleanPath] = true
 
+		// NFS volumes cannot use overlay mode
+		if vol.NFS != nil && vol.Overlay {
+			return fmt.Errorf("volume %s: overlay mode is not supported for NFS volumes", vol.VolumeID)
+		}
+
 		// Validate overlay mode requirements
 		if vol.Overlay {
 			if !vol.Readonly {
@@ -765,8 +794,11 @@ func (m *manager) buildHypervisorConfig(ctx context.Context, inst *Instance, ima
 		{Path: m.paths.InstanceConfigDisk(inst.Id), Readonly: true, IOBps: ioBps, IOBurstBps: burstBps},
 	}
 
-	// Add attached volumes as additional disks
+	// Add attached volumes as additional disks (skip NFS volumes — they're network-mounted)
 	for _, volAttach := range inst.Volumes {
+		if volAttach.NFS != nil {
+			continue // NFS volumes don't have a local block device
+		}
 		volumePath := m.volumeManager.GetVolumePath(volAttach.VolumeID)
 		if volAttach.Overlay {
 			// Base volume is always read-only when overlay is enabled

lib/instances/types.go

@@ -30,13 +30,22 @@ const (
 	EgressEnforcementModeHTTPHTTPSOnly EgressEnforcementMode = "http_https_only"
 )
 
+// VolumeNFSConfig holds NFS connection details for an NFS-backed volume attachment.
+type VolumeNFSConfig struct {
+	Server     string // NFS server hostname or IP
+	ExportPath string // NFS export path
+	Version    string // NFS protocol version (e.g., "4.1")
+	Options    string // Additional mount options
+}
+
 // VolumeAttachment represents a volume attached to an instance
 type VolumeAttachment struct {
-	VolumeID    string // Volume ID
-	MountPath   string // Mount path in guest
-	Readonly    bool   // Whether mounted read-only
-	Overlay     bool   // If true, create per-instance overlay for writes (requires Readonly=true)
-	OverlaySize int64  // Size of overlay disk in bytes (max diff from base)
+	VolumeID    string           // Volume ID
+	MountPath   string           // Mount path in guest
+	Readonly    bool             // Whether mounted read-only
+	Overlay     bool             // If true, create per-instance overlay for writes (requires Readonly=true)
+	OverlaySize int64            // Size of overlay disk in bytes (max diff from base)
+	NFS         *VolumeNFSConfig // NFS config (set for ReadWriteMany volumes, nil for block volumes)
 }
 
 // NetworkEgressPolicy configures host-mediated outbound networking behavior.