b518f11dba
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>
66 lines
1.8 KiB
Go
66 lines
1.8 KiB
Go
package containerd
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import (
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"archive/tar"
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"context"
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"io"
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"github.com/containerd/containerd/content"
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"github.com/containerd/containerd/images"
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"github.com/containerd/containerd/oci"
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ocispecs "github.com/opencontainers/image-spec/specs-go"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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)
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func (c *Client) exportToOCITar(ctx context.Context, desc ocispec.Descriptor, writer io.Writer, eopts exportOpts) error {
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tw := tar.NewWriter(writer)
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img := oci.Tar(tw)
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// For tar, we defer creating index until end of the function.
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if err := oci.Init(img, oci.InitOpts{SkipCreateIndex: true}); err != nil {
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return err
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}
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cs := c.ContentStore()
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handlers := images.Handlers(
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images.ChildrenHandler(cs),
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exportHandler(cs, img),
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)
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// For tar, we need to use Walk instead of Dispatch for ensuring sequential write
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if err := images.Walk(ctx, handlers, desc); err != nil {
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return err
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}
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// For tar, we don't use oci.PutManifestDescriptorToIndex() which allows appending desc to existing index.json
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// but requires img to support random read access so as to read index.json.
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return oci.WriteIndex(img,
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ocispec.Index{
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Versioned: ocispecs.Versioned{
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SchemaVersion: 2,
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},
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Manifests: []ocispec.Descriptor{desc},
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},
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)
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}
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func exportHandler(cs content.Store, img oci.ImageDriver) images.HandlerFunc {
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return func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
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r, err := cs.Reader(ctx, desc.Digest)
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if err != nil {
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return nil, err
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}
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w, err := oci.NewBlobWriter(img, desc.Digest.Algorithm())
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if err != nil {
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return nil, err
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}
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if _, err = io.Copy(w, r); err != nil {
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return nil, err
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}
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if err = w.Commit(desc.Size, desc.Digest); err != nil {
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return nil, err
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}
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if err = w.Close(); err != nil {
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return nil, err
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}
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return nil, nil
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}
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}
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