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package daemon
import (
"github.com/containers/image/docker/tarfile"
"github.com/containers/image/types"
"github.com/pkg/errors"
"golang.org/x/net/context"
)
type daemonImageSource struct {
ref daemonReference
*tarfile.Source // Implements most of types.ImageSource
}
type layerInfo struct {
path string
size int64
}
// newImageSource returns a types.ImageSource for the specified image reference.
// The caller must call .Close() on the returned ImageSource.
//
// It would be great if we were able to stream the input tar as it is being
// sent; but Docker sends the top-level manifest, which determines which paths
// to look for, at the end, so in we will need to seek back and re-read, several times.
// (We could, perhaps, expect an exact sequence, assume that the first plaintext file
// is the config, and that the following len(RootFS) files are the layers, but that feels
// way too brittle.)
func newImageSource(ctx *types.SystemContext, ref daemonReference) (types.ImageSource, error) {
c, err := newDockerClient(ctx)
if err != nil {
return nil, errors.Wrap(err, "Error initializing docker engine client")
}
// Per NewReference(), ref.StringWithinTransport() is either an image ID (config digest), or a !reference.NameOnly() reference.
// Either way ImageSave should create a tarball with exactly one image.
inputStream, err := c.ImageSave(context.TODO(), []string{ref.StringWithinTransport()})
if err != nil {
return nil, errors.Wrap(err, "Error loading image from docker engine")
}
defer inputStream.Close()
src, err := tarfile.NewSourceFromStream(inputStream)
if err != nil {
return nil, err
}
return &daemonImageSource{
ref: ref,
Source: src,
}, nil
}
// Reference returns the reference used to set up this source, _as specified by the user_
// (not as the image itself, or its underlying storage, claims). This can be used e.g. to determine which public keys are trusted for this image.
func (s *daemonImageSource) Reference() types.ImageReference {
return s.ref
}
// LayerInfosForCopy() returns updated layer info that should be used when reading, in preference to values in the manifest, if specified.
func (s *daemonImageSource) LayerInfosForCopy() ([]types.BlobInfo, error) {
return nil, nil
}
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