Fix USB enumeration

deviceplugin/generic.go

@@ -95,10 +95,11 @@ type GenericPlugin struct {
 	// metrics
 	deviceGauge        prometheus.Gauge
 	allocationsCounter prometheus.Counter
+	enableUSBDiscovery bool
 }
 
 // NewGenericPlugin creates a new plugin for a generic device.
-func NewGenericPlugin(ds *DeviceSpec, pluginDir string, logger log.Logger, reg prometheus.Registerer) Plugin {
+func NewGenericPlugin(ds *DeviceSpec, pluginDir string, logger log.Logger, reg prometheus.Registerer, enableUSBDiscovery bool) Plugin {
 	if logger == nil {
 		logger = log.NewNopLogger()
 	}
@@ -115,6 +116,7 @@ func NewGenericPlugin(ds *DeviceSpec, pluginDir string, logger log.Logger, reg p
 			Name: "generic_device_plugin_allocations_total",
 			Help: "The total number of device allocations made by this device plugin.",
 		}),
+		enableUSBDiscovery: enableUSBDiscovery,
 	}
 
 	if reg != nil {
@@ -129,6 +131,11 @@ func (gp *GenericPlugin) discover() (devices []device, err error) {
 	if err != nil {
 		return nil, fmt.Errorf("failed to discover path devices: %w", err)
 	}
+
+	if !gp.enableUSBDiscovery {
+		return path, nil
+	}
+
 	usb, err := gp.discoverUSB()
 	if err != nil {
 		return nil, fmt.Errorf("failed to discover usb devices: %w", err)

deviceplugin/usb.go

@@ -189,7 +189,7 @@ func queryUSBDeviceCharacteristicsByDirectory(dir os.DirEntry) (result *usbDevic
 func enumerateUSBDevices(dir string) (specs []usbDevice, err error) {
 	allDevs, err := os.ReadDir(dir)
 	if err != nil {
-		return
+		return []usbDevice{}, err
 	}
 
 	// Set up a WaitGroup with a buffered channel for results
@@ -243,7 +243,8 @@ func (gp *GenericPlugin) discoverUSB() (devices []device, err error) {
 		var paths []string
 		usbDevs, err := enumerateUSBDevices(usbDevicesDir)
 		if err != nil {
-			return devices, err
+			level.Warn(gp.logger).Log("msg", fmt.Sprintf("failed to enumerate usb devices: %s", err.Error()))
+			return devices, nil
 		}
 		for _, dev := range group.USBSpecs {
 			matches, err := searchUSBDevices(&usbDevs, dev.Vendor, dev.Product)

main.go

@@ -201,8 +201,17 @@ func Main() error {
 	pluginPath := viper.GetString("plugin-directory")
 	for i := range deviceSpecs {
 		d := deviceSpecs[i]
+
+		enableUSBDiscovery := false
+		for _, g := range d.Groups {
+			if len(g.USBSpecs) > 0 {
+				enableUSBDiscovery = true
+				break
+			}
+		}
+
 		ctx, cancel := context.WithCancel(context.Background())
-		gp := deviceplugin.NewGenericPlugin(d, pluginPath, log.With(logger, "resource", d.Name), prometheus.WrapRegistererWith(prometheus.Labels{"resource": d.Name}, r))
+		gp := deviceplugin.NewGenericPlugin(d, pluginPath, log.With(logger, "resource", d.Name), prometheus.WrapRegistererWith(prometheus.Labels{"resource": d.Name}, r), enableUSBDiscovery)
 		// Start the generic device plugin server.
 		g.Add(func() error {
 			logger.Log("msg", fmt.Sprintf("Starting the generic-device-plugin for %q.", d.Name))