github.com/containerd/containerd@v22.0.0-20200918172823-438c87b8e050+incompatible/cmd/ctr/commands/images/mount.go (about)

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package images
    18  
    19  import (
    20  	"fmt"
    21  	"time"
    22  
    23  	"github.com/containerd/containerd"
    24  	"github.com/containerd/containerd/cmd/ctr/commands"
    25  	"github.com/containerd/containerd/errdefs"
    26  	"github.com/containerd/containerd/leases"
    27  	"github.com/containerd/containerd/mount"
    28  	"github.com/containerd/containerd/platforms"
    29  	"github.com/opencontainers/image-spec/identity"
    30  	"github.com/pkg/errors"
    31  	"github.com/urfave/cli"
    32  )
    33  
    34  var mountCommand = cli.Command{
    35  	Name:      "mount",
    36  	Usage:     "mount an image to a target path",
    37  	ArgsUsage: "[flags] <ref> <target>",
    38  	Description: `Mount an image rootfs to a specified path.
    39  
    40  When you are done, use the unmount command.
    41  `,
    42  	Flags: append(append(commands.RegistryFlags, append(commands.SnapshotterFlags, commands.LabelFlag)...),
    43  		cli.BoolFlag{
    44  			Name:  "rw",
    45  			Usage: "Enable write support on the mount",
    46  		},
    47  		cli.StringFlag{
    48  			Name:  "platform",
    49  			Usage: "Mount the image for the specified platform",
    50  			Value: platforms.DefaultString(),
    51  		},
    52  	),
    53  	Action: func(context *cli.Context) (retErr error) {
    54  		var (
    55  			ref    = context.Args().First()
    56  			target = context.Args().Get(1)
    57  		)
    58  		if ref == "" {
    59  			return fmt.Errorf("please provide an image reference to mount")
    60  		}
    61  		if target == "" {
    62  			return fmt.Errorf("please provide a target path to mount to")
    63  		}
    64  
    65  		client, ctx, cancel, err := commands.NewClient(context)
    66  		if err != nil {
    67  			return err
    68  		}
    69  		defer cancel()
    70  
    71  		snapshotter := context.GlobalString("snapshotter")
    72  		if snapshotter == "" {
    73  			snapshotter = containerd.DefaultSnapshotter
    74  		}
    75  
    76  		ctx, done, err := client.WithLease(ctx,
    77  			leases.WithID(target),
    78  			leases.WithExpiration(24*time.Hour),
    79  			leases.WithLabels(map[string]string{
    80  				"containerd.io/gc.ref.snapshot." + snapshotter: target,
    81  			}),
    82  		)
    83  		if err != nil && !errdefs.IsAlreadyExists(err) {
    84  			return err
    85  		}
    86  
    87  		defer func() {
    88  			if retErr != nil && done != nil {
    89  				done(ctx)
    90  			}
    91  		}()
    92  
    93  		ps := context.String("platform")
    94  		p, err := platforms.Parse(ps)
    95  		if err != nil {
    96  			return errors.Wrapf(err, "unable to parse platform %s", ps)
    97  		}
    98  
    99  		img, err := client.ImageService().Get(ctx, ref)
   100  		if err != nil {
   101  			return err
   102  		}
   103  
   104  		i := containerd.NewImageWithPlatform(client, img, platforms.Only(p))
   105  		if err := i.Unpack(ctx, snapshotter); err != nil {
   106  			return errors.Wrap(err, "error unpacking image")
   107  		}
   108  
   109  		diffIDs, err := i.RootFS(ctx)
   110  		if err != nil {
   111  			return err
   112  		}
   113  		chainID := identity.ChainID(diffIDs).String()
   114  		fmt.Println(chainID)
   115  
   116  		s := client.SnapshotService(snapshotter)
   117  
   118  		var mounts []mount.Mount
   119  		if context.Bool("rw") {
   120  			mounts, err = s.Prepare(ctx, target, chainID)
   121  		} else {
   122  			mounts, err = s.View(ctx, target, chainID)
   123  		}
   124  		if err != nil {
   125  			if errdefs.IsAlreadyExists(err) {
   126  				mounts, err = s.Mounts(ctx, target)
   127  			}
   128  			if err != nil {
   129  				return err
   130  			}
   131  		}
   132  
   133  		if err := mount.All(mounts, target); err != nil {
   134  			if err := s.Remove(ctx, target); err != nil && !errdefs.IsNotFound(err) {
   135  				fmt.Fprintln(context.App.ErrWriter, "Error cleaning up snapshot after mount error:", err)
   136  			}
   137  			return err
   138  		}
   139  
   140  		fmt.Fprintln(context.App.Writer, target)
   141  		return nil
   142  	},
   143  }