github/containerd
4
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 2 Wiki Activity

Implement Windows mounting for bind and windows-layer mounts

Browse Source 
Using symlinks for bind mounts means we are not protecting an RO-mounted
layer against modification. Windows doesn't currently appear to offer a
better approach though, as we cannot create arbitrary empty WCOW scratch
layers at this time.

For windows-layer mounts, Unmount does not have access to the mounts
used to create it. So we store the relevant data in an Alternate Data
Stream on the mountpoint in order to be able to Unmount later.

Based on approach in https://github.com/containerd/containerd/pull/2366,
with sign-offs recorded as 'Based-on-work-by' trailers below.

This also partially-reverts some changes made in #6034 as they are not
needed with this mounting implmentation, which no longer needs to be
handled specially by the caller compared to non-Windows mounts.

Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com>
Based-on-work-by: Michael Crosby <crosbymichael@gmail.com>
Based-on-work-by: Darren Stahl <darst@microsoft.com>
This commit is contained in:
Paul "TBBle" Hampson
2020-07-23 23:19:55 +10:00
committed by Gabriel Adrian Samfira
parent 34b07d3e2d
commit 474a257b16
3 changed files with 191 additions and 47 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
pkg/cri/opts/container.go
View File

@@ -21,8 +21,6 @@ import (
"errors"
"fmt"
"os"
"path/filepath"
goruntime "runtime"
"strings"
"github.com/containerd/continuity/fs"
@@ -86,53 +84,34 @@ func WithVolumes(volumeMounts map[string]string) containerd.NewContainerOpts {
// https://github.com/containerd/containerd/pull/1785
defer os.Remove(root)
unmounter := func(mountPath string) {
if uerr := mount.Unmount(mountPath, 0); uerr != nil {
if err := mount.All(mounts, root); err != nil {
return fmt.Errorf("failed to mount: %w", err)
}
defer func() {
if uerr := mount.Unmount(root, 0); uerr != nil {
log.G(ctx).WithError(uerr).Errorf("Failed to unmount snapshot %q", root)
if err == nil {
err = uerr
}
}
}
var mountPaths []string
if goruntime.GOOS == "windows" {
for _, m := range mounts {
// appending the layerID to the root.
mountPath := filepath.Join(root, filepath.Base(m.Source))
mountPaths = append(mountPaths, mountPath)
if err := m.Mount(mountPath); err != nil {
return err
}
defer unmounter(m.Source)
}
} else {
mountPaths = append(mountPaths, root)
if err := mount.All(mounts, root); err != nil {
return fmt.Errorf("failed to mount: %w", err)
}
defer unmounter(root)
}
}()
for host, volume := range volumeMounts {
// The volume may have been defined with a C: prefix, which we can't use here.
volume = strings.TrimPrefix(volume, "C:")
for _, mountPath := range mountPaths {
src, err := fs.RootPath(mountPath, volume)
if err != nil {
return fmt.Errorf("rootpath on mountPath %s, volume %s: %w", mountPath, volume, err)
}
if _, err := os.Stat(src); err != nil {
if os.IsNotExist(err) {
// Skip copying directory if it does not exist.
continue
}
return fmt.Errorf("stat volume in rootfs: %w", err)
}
if err := copyExistingContents(src, host); err != nil {
return fmt.Errorf("taking runtime copy of volume: %w", err)
src, err := fs.RootPath(root, volume)
if err != nil {
return fmt.Errorf("rootpath on mountPath %s, volume %s: %w", root, volume, err)
}
if _, err := os.Stat(src); err != nil {
if os.IsNotExist(err) {
// Skip copying directory if it does not exist.
continue
}
return fmt.Errorf("stat volume in rootfs: %w", err)
}
if err := copyExistingContents(src, host); err != nil {
return fmt.Errorf("taking runtime copy of volume: %w", err)
}
}
return nil