graphdriver

Documentation

Index

• Constants
• Variables
• func Register(name string, initFunc InitFunc) error
• type Driver
  • func GetDriver(name, home string, options []string, uidMaps, gidMaps []idtools.IDMap) (Driver, error)
  • func New(root string, name string, options []string, uidMaps, gidMaps []idtools.IDMap) (driver Driver, err error)
  • func NewNaiveDiffDriver(driver ProtoDriver, uidMaps, gidMaps []idtools.IDMap) Driver
• type FsMagic
  • func GetFSMagic(rootpath string) (FsMagic, error)
• type InitFunc
• type NaiveDiffDriver
  • func (gdw *NaiveDiffDriver) ApplyDiff(id, parent string, diff archive.Reader) (size int64, err error)
  • func (gdw *NaiveDiffDriver) Changes(id, parent string) ([]archive.Change, error)
  • func (gdw *NaiveDiffDriver) Diff(id, parent string) (arch archive.Archive, err error)
  • func (gdw *NaiveDiffDriver) DiffSize(id, parent string) (size int64, err error)
• type ProtoDriver

Constants

const (
	// FsMagicAufs filesystem id for Aufs
	FsMagicAufs = FsMagic(0x61756673)
	// FsMagicBtrfs filesystem id for Btrfs
	FsMagicBtrfs = FsMagic(0x9123683E)
	// FsMagicCramfs filesystem id for Cramfs
	FsMagicCramfs = FsMagic(0x28cd3d45)
	// FsMagicExtfs filesystem id for Extfs
	FsMagicExtfs = FsMagic(0x0000EF53)
	// FsMagicF2fs filesystem id for F2fs
	FsMagicF2fs = FsMagic(0xF2F52010)
	// FsMagicGPFS filesystem id for GPFS
	FsMagicGPFS = FsMagic(0x47504653)
	// FsMagicJffs2Fs filesystem if for Jffs2Fs
	FsMagicJffs2Fs = FsMagic(0x000072b6)
	// FsMagicJfs filesystem id for Jfs
	FsMagicJfs = FsMagic(0x3153464a)
	// FsMagicNfsFs filesystem id for NfsFs
	FsMagicNfsFs = FsMagic(0x00006969)
	// FsMagicRAMFs filesystem id for RamFs
	FsMagicRAMFs = FsMagic(0x858458f6)
	// FsMagicReiserFs filesystem id for ReiserFs
	FsMagicReiserFs = FsMagic(0x52654973)
	// FsMagicSmbFs filesystem id for SmbFs
	FsMagicSmbFs = FsMagic(0x0000517B)
	// FsMagicSquashFs filesystem id for SquashFs
	FsMagicSquashFs = FsMagic(0x73717368)
	// FsMagicTmpFs filesystem id for TmpFs
	FsMagicTmpFs = FsMagic(0x01021994)
	// FsMagicVxFS filesystem id for VxFs
	FsMagicVxFS = FsMagic(0xa501fcf5)
	// FsMagicXfs filesystem id for Xfs
	FsMagicXfs = FsMagic(0x58465342)
	// FsMagicZfs filesystem id for Zfs
	FsMagicZfs = FsMagic(0x2fc12fc1)
)

const (
	// FsMagicUnsupported is a predefined constant value other than a valid filesystem id.
	FsMagicUnsupported = FsMagic(0x00000000)
)

Variables

var (

	// ErrNotSupported returned when driver is not supported.
	ErrNotSupported = errors.New("driver not supported")
	// ErrPrerequisites retuned when driver does not meet prerequisites.
	ErrPrerequisites = errors.New("prerequisites for driver not satisfied (wrong filesystem?)")
	// ErrIncompatibleFS returned when file system is not supported.
	ErrIncompatibleFS = fmt.Errorf("backing file system is unsupported for this graph driver")
)

var (
	// ApplyUncompressedLayer defines the unpack method used by the graph
	// driver.
	ApplyUncompressedLayer = chrootarchive.ApplyUncompressedLayer
)

var (

	// FsNames maps filesystem id to name of the filesystem.
	FsNames = map[FsMagic]string{
		FsMagicAufs:        "aufs",
		FsMagicBtrfs:       "btrfs",
		FsMagicCramfs:      "cramfs",
		FsMagicExtfs:       "extfs",
		FsMagicF2fs:        "f2fs",
		FsMagicGPFS:        "gpfs",
		FsMagicJffs2Fs:     "jffs2",
		FsMagicJfs:         "jfs",
		FsMagicNfsFs:       "nfs",
		FsMagicRAMFs:       "ramfs",
		FsMagicReiserFs:    "reiserfs",
		FsMagicSmbFs:       "smb",
		FsMagicSquashFs:    "squashfs",
		FsMagicTmpFs:       "tmpfs",
		FsMagicUnsupported: "unsupported",
		FsMagicVxFS:        "vxfs",
		FsMagicXfs:         "xfs",
		FsMagicZfs:         "zfs",
	}
)

Functions

func Register

func Register(name string, initFunc InitFunc) error

Register registers a InitFunc for the driver.

Types

type Driver

type Driver interface {
	ProtoDriver
	// Diff produces an archive of the changes between the specified
	// layer and its parent layer which may be "".
	Diff(id, parent string) (archive.Archive, error)
	// Changes produces a list of changes between the specified layer
	// and its parent layer. If parent is "", then all changes will be ADD changes.
	Changes(id, parent string) ([]archive.Change, error)
	// ApplyDiff extracts the changeset from the given diff into the
	// layer with the specified id and parent, returning the size of the
	// new layer in bytes.
	// The archive.Reader must be an uncompressed stream.
	ApplyDiff(id, parent string, diff archive.Reader) (size int64, err error)
	// DiffSize calculates the changes between the specified id
	// and its parent and returns the size in bytes of the changes
	// relative to its base filesystem directory.
	DiffSize(id, parent string) (size int64, err error)
}

Driver is the interface for layered/snapshot file system drivers.

func GetDriver

func GetDriver(name, home string, options []string, uidMaps, gidMaps []idtools.IDMap) (Driver, error)

GetDriver initializes and returns the registered driver

func New

func New(root string, name string, options []string, uidMaps, gidMaps []idtools.IDMap) (driver Driver, err error)

New creates the driver and initializes it at the specified root.

func NewNaiveDiffDriver

func NewNaiveDiffDriver(driver ProtoDriver, uidMaps, gidMaps []idtools.IDMap) Driver

NewNaiveDiffDriver returns a fully functional driver that wraps the given ProtoDriver and adds the capability of the following methods which it may or may not support on its own:

Diff(id, parent string) (archive.Archive, error)
Changes(id, parent string) ([]archive.Change, error)
ApplyDiff(id, parent string, diff archive.Reader) (size int64, err error)
DiffSize(id, parent string) (size int64, err error)

type FsMagic

type FsMagic uint32

FsMagic unsigned id of the filesystem in use.

func GetFSMagic

func GetFSMagic(rootpath string) (FsMagic, error)

GetFSMagic returns the filesystem id given the path.

type InitFunc

type InitFunc func(root string, options []string, uidMaps, gidMaps []idtools.IDMap) (Driver, error)

InitFunc initializes the storage driver.

type NaiveDiffDriver

type NaiveDiffDriver struct {
	ProtoDriver
	// contains filtered or unexported fields
}

NaiveDiffDriver takes a ProtoDriver and adds the capability of the Diffing methods which it may or may not support on its own. See the comment on the exported NewNaiveDiffDriver function below. Notably, the AUFS driver doesn't need to be wrapped like this.

func (*NaiveDiffDriver) ApplyDiff

func (gdw *NaiveDiffDriver) ApplyDiff(id, parent string, diff archive.Reader) (size int64, err error)

ApplyDiff extracts the changeset from the given diff into the layer with the specified id and parent, returning the size of the new layer in bytes.

func (*NaiveDiffDriver) Changes

func (gdw *NaiveDiffDriver) Changes(id, parent string) ([]archive.Change, error)

Changes produces a list of changes between the specified layer and its parent layer. If parent is "", then all changes will be ADD changes.

func (*NaiveDiffDriver) Diff

func (gdw *NaiveDiffDriver) Diff(id, parent string) (arch archive.Archive, err error)

Diff produces an archive of the changes between the specified layer and its parent layer which may be "".

func (*NaiveDiffDriver) DiffSize

func (gdw *NaiveDiffDriver) DiffSize(id, parent string) (size int64, err error)

DiffSize calculates the changes between the specified layer and its parent and returns the size in bytes of the changes relative to its base filesystem directory.

type ProtoDriver

type ProtoDriver interface {
	// String returns a string representation of this driver.
	String() string
	// Create creates a new, empty, filesystem layer with the
	// specified id and parent and mountLabel. Parent and mountLabel may be "".
	Create(id, parent, mountLabel string) error
	// Remove attempts to remove the filesystem layer with this id.
	Remove(id string) error
	// Get returns the mountpoint for the layered filesystem referred
	// to by this id. You can optionally specify a mountLabel or "".
	// Returns the absolute path to the mounted layered filesystem.
	Get(id, mountLabel string) (dir string, err error)
	// Put releases the system resources for the specified id,
	// e.g, unmounting layered filesystem.
	Put(id string) error
	// Exists returns whether a filesystem layer with the specified
	// ID exists on this driver.
	Exists(id string) bool
	// Status returns a set of key-value pairs which give low
	// level diagnostic status about this driver.
	Status() [][2]string
	// Returns a set of key-value pairs which give low level information
	// about the image/container driver is managing.
	GetMetadata(id string) (map[string]string, error)
	// Cleanup performs necessary tasks to release resources
	// held by the driver, e.g., unmounting all layered filesystems
	// known to this driver.
	Cleanup() error
}

ProtoDriver defines the basic capabilities of a driver. This interface exists solely to be a minimum set of methods for client code which choose not to implement the entire Driver interface and use the NaiveDiffDriver wrapper constructor.

Use of ProtoDriver directly by client code is not recommended.