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Add commands to mount/unmount image from ref
Example: ```terminal $ mkdir /opt/busybox $ ctr image mount docker.io/library/busybox:latest /opt/busybox /opt/busybox $ ls -lh /opt/busybox total 40K drwxr-xr-x 2 root root 12K Apr 14 01:10 bin drwxr-xr-x 2 root root 4.0K Apr 14 01:10 dev drwxr-xr-x 3 root root 4.0K Apr 14 01:10 etc drwxr-xr-x 2 nobody nogroup 4.0K Apr 14 01:10 home drwx------ 2 root root 4.0K Apr 14 01:10 root drwxrwxrwt 2 root root 4.0K Apr 14 01:10 tmp drwxr-xr-x 3 root root 4.0K Apr 14 01:10 usr drwxr-xr-x 4 root root 4.0K Apr 14 01:10 var $ ctr image unmount /opt/busybox $ ls -lh /opt/busybox total 0 ``` Signed-off-by: Brian Goff <cpuguy83@gmail.com>
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‎cmd/ctr/commands/images/images.go‎

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@@ -43,6 +43,8 @@ var Command = cli.Command{
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exportCommand,
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importCommand,
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listCommand,
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mountCommand,
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unmountCommand,
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pullCommand,
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pushCommand,
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removeCommand,

‎cmd/ctr/commands/images/mount.go‎

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package images
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import (
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"fmt"
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"time"
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"github.com/containerd/containerd"
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"github.com/containerd/containerd/cmd/ctr/commands"
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"github.com/containerd/containerd/errdefs"
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"github.com/containerd/containerd/leases"
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"github.com/containerd/containerd/mount"
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"github.com/containerd/containerd/platforms"
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"github.com/opencontainers/image-spec/identity"
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"github.com/pkg/errors"
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"github.com/urfave/cli"
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)
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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var mountCommand = cli.Command{
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Name: "mount",
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Usage: "mount an image to a target path",
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ArgsUsage: "[flags] <ref> <target>",
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Description: `Mount an image rootfs to a specified path.
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When you are done, use the unmount command.
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`,
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Flags: append(append(commands.RegistryFlags, append(commands.SnapshotterFlags, commands.LabelFlag)...),
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cli.BoolFlag{
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Name: "rw",
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Usage: "Enable write support on the mount",
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},
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cli.StringFlag{
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Name: "platform",
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Usage: "Mount the image for the specified platform",
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Value: platforms.DefaultString(),
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},
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),
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Action: func(context *cli.Context) (retErr error) {
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var (
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ref = context.Args().First()
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target = context.Args().Get(1)
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)
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if ref == "" {
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return fmt.Errorf("please provide an image reference to mount")
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}
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if target == "" {
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return fmt.Errorf("please provide a target path to mount to")
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}
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client, ctx, cancel, err := commands.NewClient(context)
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if err != nil {
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return err
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}
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defer cancel()
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snapshotter := context.GlobalString("snapshotter")
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if snapshotter == "" {
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snapshotter = containerd.DefaultSnapshotter
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}
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ctx, done, err := client.WithLease(ctx,
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leases.WithID(target),
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leases.WithExpiration(24*time.Hour),
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leases.WithLabels(map[string]string{
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"containerd.io/gc.ref.snapshot." + snapshotter: target,
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}),
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)
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if err != nil && !errdefs.IsAlreadyExists(err) {
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return err
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}
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defer func() {
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if retErr != nil && done != nil {
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done(ctx)
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}
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}()
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ps := context.String("platform")
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p, err := platforms.Parse(ps)
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if err != nil {
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return errors.Wrapf(err, "unable to parse platform %s", ps)
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}
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img, err := client.ImageService().Get(ctx, ref)
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if err != nil {
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return err
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}
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i := containerd.NewImageWithPlatform(client, img, platforms.Only(p))
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if err := i.Unpack(ctx, snapshotter); err != nil {
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return errors.Wrap(err, "error unpacking image")
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}
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diffIDs, err := i.RootFS(ctx)
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if err != nil {
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return err
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}
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chainID := identity.ChainID(diffIDs).String()
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fmt.Println(chainID)
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s := client.SnapshotService(snapshotter)
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var mounts []mount.Mount
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if context.Bool("rw") {
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mounts, err = s.Prepare(ctx, target, chainID)
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} else {
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mounts, err = s.View(ctx, target, chainID)
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}
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if err != nil {
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if errdefs.IsAlreadyExists(err) {
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mounts, err = s.Mounts(ctx, target)
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}
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if err != nil {
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return err
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}
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}
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if err := mount.All(mounts, target); err != nil {
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if err := s.Remove(ctx, target); err != nil && !errdefs.IsNotFound(err) {
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fmt.Fprintln(context.App.ErrWriter, "Error cleaning up snapshot after mount error:", err)
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}
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return err
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}
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fmt.Fprintln(context.App.Writer, target)
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return nil
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},
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}

‎cmd/ctr/commands/images/unmount.go‎

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package images
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import (
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"fmt"
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"github.com/containerd/containerd/cmd/ctr/commands"
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"github.com/containerd/containerd/errdefs"
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"github.com/containerd/containerd/leases"
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"github.com/containerd/containerd/mount"
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"github.com/pkg/errors"
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"github.com/urfave/cli"
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)
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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var unmountCommand = cli.Command{
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Name: "unmount",
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Usage: "unmount the image from the target",
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ArgsUsage: "[flags] <target>",
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Description: "Unmount the image rootfs from the specified target.",
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Flags: append(append(commands.RegistryFlags, append(commands.SnapshotterFlags, commands.LabelFlag)...),
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cli.BoolFlag{
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Name: "rm",
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Usage: "remove the snapshot after a successful unmount",
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},
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),
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Action: func(context *cli.Context) error {
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var (
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target = context.Args().First()
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)
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if target == "" {
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return fmt.Errorf("please provide a target path to mount to")
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}
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client, ctx, cancel, err := commands.NewClient(context)
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if err != nil {
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return err
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}
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defer cancel()
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if err := mount.UnmountAll(target, 0); err != nil {
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return err
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}
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if context.Bool("rm") {
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snapshotter := context.String("snapshotter")
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s := client.SnapshotService(snapshotter)
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if err := client.LeasesService().Delete(ctx, leases.Lease{ID: target}); err != nil && !errdefs.IsNotFound(err) {
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return errors.Wrap(err, "error deleting lease")
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}
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if err := s.Remove(ctx, target); err != nil && !errdefs.IsNotFound(err) {
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return errors.Wrap(err, "error removing snapshot")
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}
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}
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fmt.Fprintln(context.App.Writer, target)
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return nil
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},
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}

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