client: add Import() and Export() for importing/exporting image in OCI format

Export as a tar (Note: "-" can be used for stdout):

    $ ctr images export /tmp/oci-busybox.tar docker.io/library/busybox:latest

Import a tar (Note: "-" can be used for stdin):

    $ ctr images import foo/new:latest /tmp/oci-busybox.tar

Note: media types are not converted at the moment: e.g.
  application/vnd.docker.image.rootfs.diff.tar.gzip
  -> application/vnd.oci.image.layer.v1.tar+gzip

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
This commit is contained in:
Akihiro Suda
2017-06-15 08:50:20 +00:00
parent 856b038437
commit b518f11dba
13 changed files with 904 additions and 284 deletions

106
cmd/ctr/export.go Normal file
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@@ -0,0 +1,106 @@
package main
import (
"io"
"os"
"github.com/containerd/containerd/reference"
digest "github.com/opencontainers/go-digest"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
"github.com/urfave/cli"
)
var imagesExportCommand = cli.Command{
Name: "export",
Usage: "export an image",
ArgsUsage: "[flags] <out> <image>",
Description: `Export an image to a tar stream
`,
Flags: []cli.Flag{
cli.StringFlag{
Name: "oci-ref-name",
Value: "",
Usage: "Override org.opencontainers.image.ref.name annotation",
},
cli.StringFlag{
Name: "manifest",
Usage: "Digest of manifest",
},
cli.StringFlag{
Name: "manifest-type",
Usage: "Media type of manifest digest",
Value: ocispec.MediaTypeImageManifest,
},
},
Action: func(clicontext *cli.Context) error {
var (
out = clicontext.Args().First()
local = clicontext.Args().Get(1)
desc ocispec.Descriptor
)
ctx, cancel := appContext(clicontext)
defer cancel()
client, err := newClient(clicontext)
if err != nil {
return err
}
if manifest := clicontext.String("manifest"); manifest != "" {
desc.Digest, err = digest.Parse(manifest)
if err != nil {
return errors.Wrap(err, "invalid manifest digest")
}
desc.MediaType = clicontext.String("manifest-type")
} else {
img, err := client.ImageService().Get(ctx, local)
if err != nil {
return errors.Wrap(err, "unable to resolve image to manifest")
}
desc = img.Target
}
if desc.Annotations == nil {
desc.Annotations = make(map[string]string)
}
if s, ok := desc.Annotations[ocispec.AnnotationRefName]; !ok || s == "" {
if ociRefName := determineOCIRefName(local); ociRefName != "" {
desc.Annotations[ocispec.AnnotationRefName] = ociRefName
}
if ociRefName := clicontext.String("oci-ref-name"); ociRefName != "" {
desc.Annotations[ocispec.AnnotationRefName] = ociRefName
}
}
var w io.WriteCloser
if out == "-" {
w = os.Stdout
} else {
w, err = os.Create(out)
if err != nil {
return nil
}
}
r, err := client.Export(ctx, desc)
if err != nil {
return err
}
if _, err := io.Copy(w, r); err != nil {
return err
}
if err := w.Close(); err != nil {
return err
}
return r.Close()
},
}
func determineOCIRefName(local string) string {
refspec, err := reference.Parse(local)
if err != nil {
return ""
}
tag, _ := reference.SplitObject(refspec.Object)
return tag
}

View File

@@ -22,6 +22,8 @@ var imageCommand = cli.Command{
imagesListCommand,
imageRemoveCommand,
imagesSetLabelsCommand,
imagesImportCommand,
imagesExportCommand,
},
}

70
cmd/ctr/import.go Normal file
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@@ -0,0 +1,70 @@
package main
import (
"fmt"
"io"
"os"
"github.com/containerd/containerd"
"github.com/containerd/containerd/log"
"github.com/urfave/cli"
)
var imagesImportCommand = cli.Command{
Name: "import",
Usage: "import an image",
ArgsUsage: "[flags] <ref> <in>",
Description: `Import an image from a tar stream
`,
Flags: []cli.Flag{
cli.StringFlag{
Name: "ref-object",
Value: "",
Usage: "reference object e.g. tag@digest (default: use the object specified in ref)",
},
},
Action: func(clicontext *cli.Context) error {
var (
ref = clicontext.Args().First()
in = clicontext.Args().Get(1)
refObject = clicontext.String("ref-object")
)
ctx, cancel := appContext(clicontext)
defer cancel()
client, err := newClient(clicontext)
if err != nil {
return err
}
var r io.ReadCloser
if in == "-" {
r = os.Stdin
} else {
r, err = os.Open(in)
if err != nil {
return err
}
}
img, err := client.Import(ctx,
ref,
r,
containerd.WithRefObject(refObject),
)
if err != nil {
return err
}
if err = r.Close(); err != nil {
return err
}
log.G(ctx).WithField("image", ref).Debug("unpacking")
// TODO: Show unpack status
fmt.Printf("unpacking %s...", img.Target().Digest)
err = img.Unpack(ctx, clicontext.String("snapshotter"))
fmt.Println("done")
return err
},
}