graphdriver

package
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 Go to latest Published: Apr 20, 2021 License: Apache-2.0 Imports: 25 Imported by: 14

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Constants

View Source 
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)
	// FsMagicEcryptfs filesystem id for eCryptfs
	FsMagicEcryptfs = FsMagic(0xf15f)
	// 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)
	// FsMagicOverlay filesystem id for overlay
	FsMagicOverlay = FsMagic(0x794C7630)
	// FsMagicFUSE filesystem id for FUSE
	FsMagicFUSE = FsMagic(0x65735546)
)
View Source 
const (
	// FsMagicUnsupported is a predefined constant value other than a valid filesystem id.
	FsMagicUnsupported = FsMagic(0x00000000)
)

Variables

View Source 
var (

	// ErrNotSupported returned when driver is not supported.
	ErrNotSupported = errors.New("driver not supported")
	// ErrPrerequisites returned 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 = errors.New("backing file system is unsupported for this graph driver")
	// ErrLayerUnknown returned when the specified layer is unknown by the driver.
	ErrLayerUnknown = errors.New("unknown layer")
)
View Source 
var (
	// ApplyUncompressedLayer defines the unpack method used by the graph
	// driver.
	ApplyUncompressedLayer = chrootarchive.ApplyUncompressedLayer
)
View Source 
var (

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

Functions

func ChownPathByMaps 

func ChownPathByMaps(path string, toContainer, toHost *idtools.IDMappings) error

ChownPathByMaps walks the filesystem tree, changing the ownership information using the toContainer and toHost mappings, using them to replace on-disk owner UIDs and GIDs which are "host" values in the first map with UIDs and GIDs for "host" values from the second map which correspond to the same "container" IDs.

func Mounted 

func Mounted(fsType FsMagic, mountPath string) (bool, error)

Mounted checks if the given path is mounted as the fs type

func NaiveCreateFromTemplate 

func NaiveCreateFromTemplate(d TemplateDriver, id, template string, templateIDMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, opts *CreateOpts, readWrite bool) error

CreateFromTemplate creates a layer with the same contents and parent as another layer. Internally, it may even depend on that other layer continuing to exist, as if it were actually a child of the child layer.

func Register 

func Register(name string, initFunc InitFunc) error

Register registers an InitFunc for the driver.

Types

type AdditionalLayer added in v0.46.1 

type AdditionalLayer interface {
	// CreateAs creates a new layer from this additional layer
	CreateAs(id, parent string) error

	// Info returns arbitrary information stored along with this layer (i.e. `info` file)
	Info() (io.ReadCloser, error)

	// Release tells the additional layer store that we don't use this handler.
	Release()
}

AdditionalLayer reprents a layer that is stored in the additional layer store This API is experimental and can be changed without bumping the major version number.

type AdditionalLayerStoreDriver added in v0.46.1 

type AdditionalLayerStoreDriver interface {
	Driver

	// LookupAdditionalLayer looks up additional layer store by the specified
	// digest and ref and returns an object representing that layer.
	LookupAdditionalLayer(d digest.Digest, ref string) (AdditionalLayer, error)
}

AdditionalLayerStoreDriver is the interface for driver that supports additional layer store functionality. This API is experimental and can be changed without bumping the major version number.

type ApplyDiffOpts 

type ApplyDiffOpts struct {
	Diff              io.Reader
	Mappings          *idtools.IDMappings
	MountLabel        string
	IgnoreChownErrors bool
	ForceMask         *os.FileMode
}

ApplyDiffOpts contains optional arguments for ApplyDiff methods.

type Capabilities 

type Capabilities struct {
	// Flags that this driver is capable of reproducing exactly equivalent
	// diffs for read-only layers. If set, clients can rely on the driver
	// for consistent tar streams, and avoid extra processing to account
	// for potential differences (eg: the layer store's use of tar-split).
	ReproducesExactDiffs bool
}

Capabilities defines a list of capabilities a driver may implement. These capabilities are not required; however, they do determine how a graphdriver can be used.

type CapabilityDriver 

type CapabilityDriver interface {
	Capabilities() Capabilities
}

CapabilityDriver is the interface for layered file system drivers that can report on their Capabilities.

type Checker 

type Checker interface {
	// IsMounted returns true if the provided path is mounted for the specific checker
	IsMounted(path string) bool
}

Checker makes checks on specified filesystems.

func NewDefaultChecker 

func NewDefaultChecker() Checker

NewDefaultChecker returns a check that parses /proc/mountinfo to check if the specified path is mounted.

func NewFsChecker 

func NewFsChecker(t FsMagic) Checker

NewFsChecker returns a checker configured for the provided FsMagic

type CreateOpts 

type CreateOpts struct {
	MountLabel string
	StorageOpt map[string]string
	*idtools.IDMappings
	// contains filtered or unexported fields
}

CreateOpts contains optional arguments for Create() and CreateReadWrite() methods.

type DiffDriver 

type DiffDriver interface {
	// Diff produces an archive of the changes between the specified
	// layer and its parent layer which may be "".
	Diff(id string, idMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, mountLabel string) (io.ReadCloser, 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 string, idMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, mountLabel 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 io.Reader must be an uncompressed stream.
	ApplyDiff(id string, parent string, options ApplyDiffOpts) (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 string, idMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, mountLabel string) (size int64, err error)
}

DiffDriver is the interface to use to implement graph diffs

type DiffGetterDriver 

type DiffGetterDriver interface {
	Driver
	// DiffGetter returns an interface to efficiently retrieve the contents
	// of files in a layer.
	DiffGetter(id string) (FileGetCloser, error)
}

DiffGetterDriver is the interface for layered file system drivers that provide a specialized function for getting file contents for tar-split.

type Driver 

type Driver interface {
	ProtoDriver
	DiffDriver
	LayerIDMapUpdater
}

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

func GetDriver 

func GetDriver(name string, config Options) (Driver, error)

GetDriver initializes and returns the registered driver

func New 

func New(name string, config Options) (Driver, error)

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

func NewNaiveDiffDriver 

func NewNaiveDiffDriver(driver ProtoDriver, updater LayerIDMapUpdater) 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 string, idMappings *idtools.IDMappings, parent string, parentMappings *idtools.IDMappings, mountLabel string) (io.ReadCloser, error)
Changes(id string, idMappings *idtools.IDMappings, parent string, parentMappings *idtools.IDMappings, mountLabel string) ([]archive.Change, error)
ApplyDiff(id, parent string, options ApplyDiffOpts) (size int64, err error)
DiffSize(id string, idMappings *idtools.IDMappings, parent, parentMappings *idtools.IDMappings, mountLabel string) (size int64, err error)

type FileGetCloser 

type FileGetCloser interface {
	storage.FileGetter
	// Close cleans up any resources associated with the FileGetCloser.
	Close() error
}

FileGetCloser extends the storage.FileGetter interface with a Close method for cleaning up.

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(homedir string, options Options) (Driver, error)

InitFunc initializes the storage driver.

type LayerIDMapUpdater 

type LayerIDMapUpdater interface {
	// UpdateLayerIDMap walks the layer's filesystem tree, changing the ownership
	// information using the toContainer and toHost mappings, using them to replace
	// on-disk owner UIDs and GIDs which are "host" values in the first map with
	// UIDs and GIDs for "host" values from the second map which correspond to the
	// same "container" IDs.  This method should only be called after a layer is
	// first created and populated, and before it is mounted, as other changes made
	// relative to a parent layer, but before this method is called, may be discarded
	// by Diff().
	UpdateLayerIDMap(id string, toContainer, toHost *idtools.IDMappings, mountLabel string) error

	// SupportsShifting tells whether the driver support shifting of the UIDs/GIDs in a
	// image and it is not required to Chown the files when running in an user namespace.
	SupportsShifting() bool
}

LayerIDMapUpdater is the interface that implements ID map changes for layers.

func NewNaiveLayerIDMapUpdater 

func NewNaiveLayerIDMapUpdater(driver ProtoDriver) LayerIDMapUpdater

NewNaiveLayerIDMapUpdater wraps the ProtoDriver in a LayerIDMapUpdater that uses ChownPathByMaps to update the ownerships in a layer's filesystem tree.

type MountOpts 

type MountOpts struct {
	// Mount label is the MAC Labels to assign to mount point (SELINUX)
	MountLabel string
	// UidMaps & GidMaps are the User Namespace mappings to be assigned to content in the mount point
	UidMaps []idtools.IDMap // nolint: golint
	GidMaps []idtools.IDMap // nolint: golint
	Options []string

	// Volatile specifies whether the container storage can be optimized
	// at the cost of not syncing all the dirty files in memory.
	Volatile bool
}

MountOpts contains optional arguments for LayerStope.Mount() methods.

type NaiveDiffDriver 

type NaiveDiffDriver struct {
	ProtoDriver
	LayerIDMapUpdater
}

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, options ApplyDiffOpts) (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 string, idMappings *idtools.IDMappings, parent string, parentMappings *idtools.IDMappings, mountLabel 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 string, idMappings *idtools.IDMappings, parent string, parentMappings *idtools.IDMappings, mountLabel string) (arch io.ReadCloser, 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 string, idMappings *idtools.IDMappings, parent string, parentMappings *idtools.IDMappings, mountLabel 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 Options 

type Options struct {
	Root                string
	RunRoot             string
	DriverOptions       []string
	UIDMaps             []idtools.IDMap
	GIDMaps             []idtools.IDMap
	ExperimentalEnabled bool
}

Options is used to initialize a graphdriver

type ProtoDriver 

type ProtoDriver interface {
	// String returns a string representation of this driver.
	String() string
	// CreateReadWrite creates a new, empty filesystem layer that is ready
	// to be used as the storage for a container. Additional options can
	// be passed in opts. parent may be "" and opts may be nil.
	CreateReadWrite(id, parent string, opts *CreateOpts) error
	// Create creates a new, empty, filesystem layer with the
	// specified id and parent and options passed in opts. Parent
	// may be "" and opts may be nil.
	Create(id, parent string, opts *CreateOpts) error
	// CreateFromTemplate creates a new filesystem layer with the specified id
	// and parent, with contents identical to the specified template layer.
	CreateFromTemplate(id, template string, templateIDMappings *idtools.IDMappings, parent string, parentIDMappings *idtools.IDMappings, opts *CreateOpts, readWrite bool) 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 "".
	// Optionally it gets the mappings used to create the layer.
	// Returns the absolute path to the mounted layered filesystem.
	Get(id string, options MountOpts) (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.
	Metadata(id string) (map[string]string, error)
	// ReadWriteDiskUsage returns the disk usage of the writable directory for the specified ID.
	ReadWriteDiskUsage(id string) (*directory.DiskUsage, error)
	// Cleanup performs necessary tasks to release resources
	// held by the driver, e.g., unmounting all layered filesystems
	// known to this driver.
	Cleanup() error
	// AdditionalImageStores returns additional image stores supported by the driver
	// This API is experimental and can be changed without bumping the major version number.
	AdditionalImageStores() []string
}

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.

type RefCounter 

type RefCounter struct {
	// contains filtered or unexported fields
}

RefCounter is a generic counter for use by graphdriver Get/Put calls

func NewRefCounter 

func NewRefCounter(c Checker) *RefCounter

NewRefCounter returns a new RefCounter

func (*RefCounter) Decrement 

func (c *RefCounter) Decrement(path string) int

Decrement decreases the ref count for the given id and returns the current count

func (*RefCounter) Increment 

func (c *RefCounter) Increment(path string) int

Increment increases the ref count for the given id and returns the current count

type TemplateDriver 

type TemplateDriver interface {
	DiffDriver
	CreateReadWrite(id, parent string, opts *CreateOpts) error
	Create(id, parent string, opts *CreateOpts) error
	Remove(id string) error
}

TemplateDriver is just barely enough of a driver that we can implement a naive version of CreateFromTemplate on top of it.

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