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Implement Windows snapshotter and differ
This implements the Windows snapshotter and diff Apply function. This allows for Windows layers to be created, and layers to be pulled from the hub. Signed-off-by: Darren Stahl <[email protected]>
1 parent 12eaf13 commit a5a9f91

8 files changed

Lines changed: 577 additions & 33 deletions

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‎cmd/containerd/builtins_windows.go‎

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Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
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package main
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import (
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_ "github.com/containerd/containerd/diff/windows"
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_ "github.com/containerd/containerd/snapshots/windows"
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_ "github.com/containerd/containerd/windows"
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)

‎diff/windows/windows.go‎

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// +build windows
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package windows
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import (
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"io"
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"io/ioutil"
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"strings"
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"time"
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winio "github.com/Microsoft/go-winio"
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"github.com/containerd/containerd/archive"
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"github.com/containerd/containerd/archive/compression"
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"github.com/containerd/containerd/content"
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"github.com/containerd/containerd/diff"
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"github.com/containerd/containerd/errdefs"
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"github.com/containerd/containerd/images"
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"github.com/containerd/containerd/log"
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"github.com/containerd/containerd/metadata"
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"github.com/containerd/containerd/mount"
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"github.com/containerd/containerd/platforms"
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"github.com/containerd/containerd/plugin"
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digest "github.com/opencontainers/go-digest"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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"golang.org/x/net/context"
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)
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func init() {
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plugin.Register(&plugin.Registration{
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Type: plugin.DiffPlugin,
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ID: "windows",
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Requires: []plugin.Type{
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plugin.MetadataPlugin,
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},
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InitFn: func(ic *plugin.InitContext) (interface{}, error) {
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md, err := ic.Get(plugin.MetadataPlugin)
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if err != nil {
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return nil, err
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}
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ic.Meta.Platforms = append(ic.Meta.Platforms, platforms.DefaultSpec())
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return NewWindowsDiff(md.(*metadata.DB).ContentStore())
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},
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})
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}
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type windowsDiff struct {
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store content.Store
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}
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var emptyDesc = ocispec.Descriptor{}
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// NewWindowsDiff is the Windows container layer implementation of diff.Differ.
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func NewWindowsDiff(store content.Store) (diff.Differ, error) {
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return &windowsDiff{
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store: store,
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}, nil
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}
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// Apply applies the content associated with the provided digests onto the
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// provided mounts. Archive content will be extracted and decompressed if
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// necessary.
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func (s *windowsDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount) (d ocispec.Descriptor, err error) {
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t1 := time.Now()
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defer func() {
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if err == nil {
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log.G(ctx).WithFields(logrus.Fields{
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"d": time.Now().Sub(t1),
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"dgst": desc.Digest,
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"size": desc.Size,
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"media": desc.MediaType,
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}).Debugf("diff applied")
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}
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}()
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var isCompressed bool
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switch desc.MediaType {
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case ocispec.MediaTypeImageLayer, images.MediaTypeDockerSchema2Layer:
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case ocispec.MediaTypeImageLayerGzip, images.MediaTypeDockerSchema2LayerGzip:
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isCompressed = true
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default:
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// Still apply all generic media types *.tar[.+]gzip and *.tar
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if strings.HasSuffix(desc.MediaType, ".tar.gzip") || strings.HasSuffix(desc.MediaType, ".tar+gzip") {
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isCompressed = true
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} else if !strings.HasSuffix(desc.MediaType, ".tar") {
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return emptyDesc, errors.Wrapf(errdefs.ErrNotImplemented, "unsupported diff media type: %v", desc.MediaType)
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}
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}
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ra, err := s.store.ReaderAt(ctx, desc.Digest)
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if err != nil {
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return emptyDesc, errors.Wrap(err, "failed to get reader from content store")
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}
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defer ra.Close()
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r := content.NewReader(ra)
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if isCompressed {
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ds, err := compression.DecompressStream(r)
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if err != nil {
101+
return emptyDesc, err
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}
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defer ds.Close()
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r = ds
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}
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digester := digest.Canonical.Digester()
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rc := &readCounter{
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r: io.TeeReader(r, digester.Hash()),
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}
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layer, parentLayerPaths, err := mountsToLayerAndParents(mounts)
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if err != nil {
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return emptyDesc, err
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}
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// TODO darrenstahlmsft: When this is done isolated, we should disable these.
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// it currently cannot be disabled, unless we add ref counting. Since this is
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// temporary, leaving it enabled is OK for now.
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if err := winio.EnableProcessPrivileges([]string{winio.SeBackupPrivilege, winio.SeRestorePrivilege}); err != nil {
121+
return emptyDesc, err
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}
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if _, err := archive.Apply(ctx, layer, rc, archive.WithParentLayers(parentLayerPaths), archive.AsWindowsContainerLayer()); err != nil {
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return emptyDesc, err
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}
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// Read any trailing data
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if _, err := io.Copy(ioutil.Discard, rc); err != nil {
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return emptyDesc, err
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}
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return ocispec.Descriptor{
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MediaType: ocispec.MediaTypeImageLayer,
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Size: rc.c,
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Digest: digester.Digest(),
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}, nil
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}
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// DiffMounts creates a diff between the given mounts and uploads the result
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// to the content store.
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func (s *windowsDiff) DiffMounts(ctx context.Context, lower, upper []mount.Mount, opts ...diff.Opt) (d ocispec.Descriptor, err error) {
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panic("not implemented on Windows")
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}
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type readCounter struct {
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r io.Reader
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c int64
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}
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func (rc *readCounter) Read(p []byte) (n int, err error) {
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n, err = rc.r.Read(p)
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rc.c += int64(n)
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return
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}
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func mountsToLayerAndParents(mounts []mount.Mount) (string, []string, error) {
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if len(mounts) != 1 {
159+
return "", nil, errors.Wrap(errdefs.ErrInvalidArgument, "number of mounts should always be 1 for Windows layers")
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}
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layer := mounts[0].Source
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parentLayerPaths, err := mounts[0].GetParentPaths()
164+
if err != nil {
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return "", nil, err
166+
}
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168+
return layer, parentLayerPaths, nil
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}

‎mount/mount_windows.go‎

Lines changed: 70 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,13 @@
11
package mount
22

3-
import "github.com/pkg/errors"
3+
import (
4+
"encoding/json"
5+
"path/filepath"
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"strings"
7+
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"github.com/Microsoft/hcsshim"
9+
"github.com/pkg/errors"
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)
411

512
var (
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// ErrNotImplementOnWindows is returned when an action is not implemented for windows
@@ -9,15 +16,73 @@ var (
916

1017
// Mount to the provided target
1118
func (m *Mount) Mount(target string) error {
12-
return ErrNotImplementOnWindows
19+
home, layerID := filepath.Split(m.Source)
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21+
parentLayerPaths, err := m.GetParentPaths()
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if err != nil {
23+
return err
24+
}
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26+
var di = hcsshim.DriverInfo{
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HomeDir: home,
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}
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30+
if err = hcsshim.ActivateLayer(di, layerID); err != nil {
31+
return errors.Wrapf(err, "failed to activate layer %s", m.Source)
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}
33+
defer func() {
34+
if err != nil {
35+
hcsshim.DeactivateLayer(di, layerID)
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}
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}()
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39+
if err = hcsshim.PrepareLayer(di, layerID, parentLayerPaths); err != nil {
40+
return errors.Wrapf(err, "failed to prepare layer %s", m.Source)
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}
42+
defer func() {
43+
if err != nil {
44+
hcsshim.UnprepareLayer(di, layerID)
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}
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}()
47+
return nil
48+
}
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50+
// ParentLayerPathsFlag is the options flag used to represent the JSON encoded
51+
// list of parent layers required to use the layer
52+
const ParentLayerPathsFlag = "parentLayerPaths="
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54+
// GetParentPaths of the mount
55+
func (m *Mount) GetParentPaths() ([]string, error) {
56+
var parentLayerPaths []string
57+
for _, option := range m.Options {
58+
if strings.HasPrefix(option, ParentLayerPathsFlag) {
59+
err := json.Unmarshal([]byte(option[len(ParentLayerPathsFlag):]), &parentLayerPaths)
60+
if err != nil {
61+
return nil, errors.Wrap(err, "failed to unmarshal parent layer paths from mount")
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}
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}
64+
}
65+
return parentLayerPaths, nil
1366
}
1467

1568
// Unmount the mount at the provided path
1669
func Unmount(mount string, flags int) error {
17-
return ErrNotImplementOnWindows
70+
home, layerID := filepath.Split(mount)
71+
var di = hcsshim.DriverInfo{
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HomeDir: home,
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}
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75+
if err := hcsshim.UnprepareLayer(di, layerID); err != nil {
76+
return errors.Wrapf(err, "failed to unprepare layer %s", mount)
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}
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if err := hcsshim.DeactivateLayer(di, layerID); err != nil {
79+
return errors.Wrapf(err, "failed to deactivate layer %s", mount)
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}
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82+
return nil
1883
}
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20-
// UnmountAll mounts at the provided path
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// UnmountAll unmounts from the provided path
2186
func UnmountAll(mount string, flags int) error {
22-
return ErrNotImplementOnWindows
87+
return Unmount(mount, flags)
2388
}

‎services/diff/service.go‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -30,9 +30,7 @@ func init() {
3030
Requires: []plugin.Type{
3131
plugin.DiffPlugin,
3232
},
33-
Config: &config{
34-
Order: []string{"walking"},
35-
},
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Config: defaultDifferConfig,
3634
InitFn: func(ic *plugin.InitContext) (interface{}, error) {
3735
differs, err := ic.GetByType(plugin.DiffPlugin)
3836
if err != nil {

‎services/diff/service_unix.go‎

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Original file line numberDiff line numberDiff line change
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// +build !windows
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3+
package diff
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5+
var defaultDifferConfig = &config{
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Order: []string{"walking"},
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}

‎services/diff/service_windows.go‎

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Original file line numberDiff line numberDiff line change
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// +build windows
2+
3+
package diff
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var defaultDifferConfig = &config{
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Order: []string{"windows"},
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}

‎snapshots/windows/utilities.go‎

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Original file line numberDiff line numberDiff line change
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// +build windows
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3+
package windows
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5+
import (
6+
"context"
7+
8+
"github.com/containerd/containerd/log"
9+
"github.com/containerd/containerd/snapshots/storage"
10+
)
11+
12+
func rollbackWithLogging(ctx context.Context, t storage.Transactor) {
13+
if err := t.Rollback(); err != nil {
14+
log.G(ctx).WithError(err).Warn("failed to rollback transaction")
15+
}
16+
}

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