layer

type AfterLayerUnpackCallback ¶ added in v0.4.6

type AfterLayerUnpackCallback func(manifest ispec.Manifest, desc ispec.Descriptor) error

AfterLayerUnpackCallback is called after each layer is unpacked.

type DirRootfs ¶ added in v0.5.0

type DirRootfs struct {
	// MapOptions represent the userns mappings that should be applied ot this
	// rootfs.
	MapOptions MapOptions
}

DirRootfs is the default OnDiskFormat used by umoci, and is designed to be used to extract a filesystem into a single directory on a regular unix filesystem. In order to generate a new diff layer, it is necessary to use mtree manifests to track changes.

func (fs DirRootfs) Map() MapOptions

type MapOptions ¶

type MapOptions struct {
	// UIDMappings and GIDMappings are the UID and GID mappings to apply when
	// packing and unpacking image rootfs layers.
	UIDMappings []rspec.LinuxIDMapping `json:"uid_mappings"`
	GIDMappings []rspec.LinuxIDMapping `json:"gid_mappings"`

	// Rootless specifies whether any to error out if chown fails.
	Rootless bool `json:"rootless"`
}

MapOptions specifies the UID and GID mappings used when unpacking and repacking images, and whether the mapping is being done as a rootless user.

type OnDiskFormat ¶ added in v0.5.0

type OnDiskFormat interface {

	// Map returns the format-agnostic information about userns mapping.
	Map() MapOptions
	// contains filtered or unexported methods
}

OnDiskFormat represents the on-disk file format that is used when extracting and assumed when repacking a rootfs.

DirRootfs is the default format used by umoci, and is designed to be used to extract a filesystem into a single directory on a regular unix filesystem. In order to generate a new diff layer, it is necessary to use mtree manifests to track changes.

OverlayfsRootfs is an alternative format that is intended to be used with overlayfs to avoid the need for mtree manifests. This means that layers are intended to be extracted into separate directories and merged together with overlayfs, which also means that OCI whiteouts are converted to and from overlayfs's format.

NOTE: At the moment OverlayfsRootfs cannot be used with the command-line version of umoci nor the top-level umoci helpers, and most of the umoci API still includes dependencies on mtree manifests (but you can pass a nil manifest if using OverlayfsRootfs).

type OverlayfsRootfs ¶ added in v0.5.0

type OverlayfsRootfs struct {
	// MapOptions represent the userns mappings that should be applied ot this
	// rootfs.
	MapOptions MapOptions

	// UserXattr indicates whether this overlayfs rootfs is going to be mounted
	// using the "userxattr" mount option for overlayfs. If set, then rather
	// than using the "trusted.overlay.*" xattr namespace (the default),
	// "user.overlay.*" will be used instead.
	UserXattr bool
}

OverlayfsRootfs is an alternative OnDiskFormat to the default DirRootfs format that is intended to be used with overlayfs to avoid the need for mtree manifests. This means that layers are intended to be extracted into separate directories and merged together with overlayfs, which also means that OCI whiteouts are converted to and from overlayfs's format.

NOTE: At the moment OverlayfsRootfs cannot be used with the command-line version of umoci nor the top-level umoci helpers, and most of the umoci API still includes dependencies on mtree manifests (but you can pass a nil manifest if using OverlayfsRootfs).

func (fs OverlayfsRootfs) Map() MapOptions

type RepackOptions ¶ added in v0.4.7

type RepackOptions struct {
	// OnDiskFormat is what on-disk format the rootfs we are generating a layer
	// from uses. [OverlayfsRootfs] will cause overlayfs format whiteouts to be
	// converted to OCI whiteouts in the layer.
	OnDiskFormat OnDiskFormat

	// SourceDateEpoch, if set, specifies the timestamp to use for clamping
	// layer content timestamps. If not set, layer content timestamps are
	// preserved as-is.
	SourceDateEpoch *time.Time
}

RepackOptions describes the behavior of the various GenerateLayer operations.

func (opt RepackOptions) MapOptions() MapOptions

type TarExtractor ¶ added in v0.4.2

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

TarExtractor represents a tar file to be extracted.

func NewTarExtractor(opt *UnpackOptions) *TarExtractor

func (te *TarExtractor) UnpackEntry(root string, hdr *tar.Header, r io.Reader) (Err error)

type UnpackOptions ¶ added in v0.4.7

type UnpackOptions struct {
	// OnDiskFormat is what extraction format is used when writing to the
	// filesystem. [OverlayfsRootfs] will cause whiteouts to be represented as
	// whiteout inodes in the overlayfs format.
	OnDiskFormat OnDiskFormat

	// KeepDirlinks is essentially the same as rsync's --keep-dirlinks option.
	// If, on extraction, a directory would be created where a symlink to a
	// directory previously existed, KeepDirlinks doesn't create that
	// directory, but instead just uses the existing symlink.
	KeepDirlinks bool

	// AfterLayerUnpack is a function that's called after every layer is
	// unpacked.
	AfterLayerUnpack AfterLayerUnpackCallback

	// StartFrom is the descriptor in the manifest to start unpacking from.
	StartFrom ispec.Descriptor
}

UnpackOptions describes the behavior of the various unpack operations.

func (opt UnpackOptions) MapOptions() MapOptions