github/containerd
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 2 Wiki Activity

Add documentation to rootfs functions

Browse Source 
Clarifies role of varies rootfs functions as well as their return values.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan 2017-07-12 13:57:51 -07:00
parent fba7463ed3
commit 4f388e0e27
No known key found for this signature in database
GPG Key ID: F58C5D0A4405ACDB
2 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
rootfs/apply.go
View File

@ -14,15 +14,24 @@ import (
"golang.org/x/net/context"
)
// Applier is used to apply a descriptor of a layer diff on top of mounts.
type Applier interface {
Apply(context.Context, ocispec.Descriptor, []mount.Mount) (ocispec.Descriptor, error)
}
// Layer represents the descriptors for a layer diff. These descriptions
// include the descriptor for the uncompressed tar diff as well as a blob
// used to transport that tar. The blob descriptor may or may not describe
// a compressed object.
type Layer struct {
Diff ocispec.Descriptor
Blob ocispec.Descriptor
}
// ApplyLayers applies all the layers using the given snapshotter and applier.
// The returned result is a chain id digest representing all the applied layers.
// Layers are applied in order they are given, making the first layer the
// bottom-most layer in the layer chain.
func ApplyLayers(ctx context.Context, layers []Layer, sn snapshot.Snapshotter, a Applier) (digest.Digest, error) {
var chain []digest.Digest
for _, layer := range layers {
@ -36,6 +45,9 @@ func ApplyLayers(ctx context.Context, layers []Layer, sn snapshot.Snapshotter, a
return identity.ChainID(chain), nil
}
// ApplyLayer applies a single layer on top of the given provided layer chain,
// using the provided snapshotter and applier. If the layer was unpacked true
// is returned, if the layer already exists false is returned.
func ApplyLayer(ctx context.Context, layer Layer, chain []digest.Digest, sn snapshot.Snapshotter, a Applier) (bool, error) {
var (
parent = identity.ChainID(chain)

15
rootfs/diff.go
View File

@ -3,23 +3,24 @@ package rootfs
import (
"fmt"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/mount"
"github.com/containerd/containerd/snapshot"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
"golang.org/x/net/context"
)
// MountDiffer computes the difference between two mounts and returns a
// descriptor for the computed diff. The provided ref can be used to track
// the content creation of the diff and media type is used to determine the
// format of the created content.
type MountDiffer interface {
DiffMounts(ctx context.Context, lower, upper []mount.Mount, media, ref string) (ocispec.Descriptor, error)
}
type DiffOptions struct {
MountDiffer
content.Store
snapshot.Snapshotter
}
// Diff creates a layer diff for the given snapshot identifier from the parent
// of the snapshot. A content ref is provided to track the progress of the
// content creation and the provided snapshotter and mount differ are used
// for calculating the diff. The descriptor for the layer diff is returned.
func Diff(ctx context.Context, snapshotID, contentRef string, sn snapshot.Snapshotter, md MountDiffer) (ocispec.Descriptor, error) {
info, err := sn.Stat(ctx, snapshotID)
if err != nil {