add capability endpoint to decide flex volume

core/compute/compute_common.go

@@ -144,7 +144,9 @@ func setupVolumes(config *container.Config, instance model.Instance, hostConfig
 	rancherManagedVolumeNames := map[string]struct{}{}
 	if vMounts := instance.VolumesFromDataVolumeMounts; len(vMounts) > 0 {
 		for _, volume := range vMounts {
-			if storage.IsRancherVolume(volume) {
+			if ok, err := storage.IsRancherVolume(volume); err != nil {
+				return err
+			} else if ok {
 				rancherManagedVolumeNames[volume.Name] = struct{}{}
 			}
 		}
@@ -208,7 +210,9 @@ func setupVolumes(config *container.Config, instance model.Instance, hostConfig
 		for _, vMount := range vMounts {
 			storagePool := model.StoragePool{}
 			// volume active == exists, possibly not attached to this host
-			if !storage.IsRancherVolume(vMount) {
+			if ok, err := storage.IsRancherVolume(vMount); err != nil {
+				return err
+			} else if !ok {
 				if ok, err := storage.IsVolumeActive(vMount, storagePool, client); !ok && err == nil {
 					if err := storage.DoVolumeActivate(vMount, storagePool, progress, client); err != nil {
 						return errors.Wrap(err, constants.SetupVolumesError+"failed to activate volume")

core/compute/compute_unix.go

@@ -487,7 +487,9 @@ func configureDNS(dockerClient *client.Client, containerID string) error {
 
 func setupRancherFlexVolume(instance model.Instance, hostConfig *container.HostConfig) error {
 	for _, volume := range instance.VolumesFromDataVolumeMounts {
-		if storage.IsRancherVolume(volume) {
+		if ok, err := storage.IsRancherVolume(volume); err != nil {
+			return err
+		} else if ok {
 			payload := struct {
 				Name    string
 				Options map[string]string `json:"Opts,omitempty"`
@@ -527,7 +529,9 @@ func setupRancherFlexVolume(instance model.Instance, hostConfig *container.HostC
 
 func unmountRancherFlexVolume(instance model.Instance) error {
 	for _, volume := range instance.VolumesFromDataVolumeMounts {
-		if storage.IsRancherVolume(volume) {
+		if ok, err := storage.IsRancherVolume(volume); err != nil {
+			return err
+		} else if ok {
 			payload := struct{ Name string }{Name: volume.Name}
 			_, err := storage.CallRancherStorageVolumePlugin(volume, storage.Unmount, payload)
 			if err != nil {

core/storage/volume.go

@@ -252,11 +252,31 @@ func rancherStorageSockPath(volume model.Volume) string {
 	return filepath.Join(rancherSockDir, volume.Data.Fields.Driver+".sock")
 }
 
-func IsRancherVolume(volume model.Volume) bool {
+// IsRancherVolume checks if a volume to be considered as a flex volume if it is in rancherDrivers and the capability is flex
+// raise an error if its rancher-managed driver but the socket file is not available
+func IsRancherVolume(volume model.Volume) (bool, error) {
 	if _, ok := rancherDrivers[volume.Data.Fields.Driver]; ok {
-		return true
+		if _, err := os.Stat(rancherStorageSockPath(volume)); err == nil {
+			// check if Capabilities is flex
+			payload := struct {
+				Name    string
+				Options map[string]string `json:"Opts,omitempty"`
+			}{
+				Name:    volume.Name,
+				Options: volume.Data.Fields.DriverOpts,
+			}
+			response, err := CallRancherStorageVolumePlugin(volume, Capabilities, payload)
+			if err != nil {
+				return false, err
+			}
+			if response.Capabilities.Scope == "flex" {
+				return true, nil
+			}
+			return false, nil
+		}
+		return false, errors.Errorf("socket file not found at %s", rancherStorageSockPath(volume))
 	}
-	return false
+	return false, nil
 }
 
 func IsVolumeRemoved(volume model.Volume, storagePool model.StoragePool, client *engineCli.Client) (bool, error) {

handlers/storage.go

@@ -68,7 +68,9 @@ func (h *StorageHandler) VolumeActivate(event *revents.Event, cli *client.Ranche
 	progress := utils.GetProgress(event, cli)
 
 	// if its rancher volume, use flexVolume and bypass docker volume plugin
-	if storage.IsRancherVolume(volume) {
+	if ok, err := storage.IsRancherVolume(volume); err != nil {
+		return err
+	} else if ok {
 		err := storage.VolumeActivateFlex(volume)
 		if err != nil {
 			return err
@@ -93,7 +95,9 @@ func (h *StorageHandler) VolumeRemove(event *revents.Event, cli *client.RancherC
 	storagePool := volumeStoragePoolMap.StoragePool
 	progress := utils.GetProgress(event, cli)
 
-	if storage.IsRancherVolume(volume) {
+	if ok, err := storage.IsRancherVolume(volume); err != nil {
+		return err
+	} else if ok {
 		// we need to make sure the reference is cleaned up in docker, so if it exists in docker then clean up in docker first
 		if inspect, err := h.dockerClient.VolumeInspect(context.Background(), volume.Name); err != nil && !engineCli.IsErrVolumeNotFound(err) {
 			return errors.Wrapf(err, constants.VolumeRemoveError+"failed to inspect volume %v", volume.Name)