volume

type Metrics struct {
	// Used represents the total bytes used by the Volume.
	// Note: For block devices this maybe more than the total size of the files.
	Used *resource.Quantity

	// Capacity represents the total capacity (bytes) of the volume's
	// underlying storage. For Volumes that share a filesystem with the host
	// (e.g. emptydir, hostpath) this is the size of the underlying storage,
	// and will not equal Used + Available as the fs is shared.
	Capacity *resource.Quantity

	// Available represents the storage space available (bytes) for the
	// Volume. For Volumes that share a filesystem with the host (e.g.
	// emptydir, hostpath), this is the available space on the underlying
	// storage, and is shared with host processes and other Volumes.
	Available *resource.Quantity

	// InodesUsed represents the total inodes used by the Volume.
	InodesUsed *resource.Quantity

	// Inodes represents the total number of inodes available in the volume.
	// For volumes that share a filesystem with the host (e.g. emptydir, hostpath),
	// this is the inodes available in the underlying storage,
	// and will not equal InodesUsed + InodesFree as the fs is shared.
	Inodes *resource.Quantity

	// InodesFree represent the inodes available for the volume.  For Volumes that share
	// a filesystem with the host (e.g. emptydir, hostpath), this is the free inodes
	// on the underlying storage, and is shared with host processes and other volumes
	InodesFree *resource.Quantity

	// Normal volumes are available for use and operating optimally.
	// An abnormal volume does not meet these criteria.
	// This field is OPTIONAL. Only some csi drivers which support NodeServiceCapability_RPC_VOLUME_CONDITION
	// need to fill it.
	Abnormal *bool

	// The message describing the condition of the volume.
	// This field is OPTIONAL. Only some csi drivers which support capability_RPC_VOLUME_CONDITION
	// need to fill it.
	Message *string
}

type MetricsError struct {
	Code int
	Msg  string
}

type MetricsProvider interface {
	// GetMetrics returns the Metrics for the Volume. Maybe expensive for
	// some implementations.
	GetMetrics() (*Metrics, error)
}