mirror of https://github.com/containers/image.git
55 lines
2.1 KiB
Go
55 lines
2.1 KiB
Go
package daemon
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import (
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"context"
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"github.com/containers/image/v5/docker/internal/tarfile"
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"github.com/containers/image/v5/internal/private"
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"github.com/containers/image/v5/types"
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perrors "github.com/pkg/errors"
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)
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type daemonImageSource struct {
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ref daemonReference
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*tarfile.Source // Implements most of types.ImageSource
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}
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// newImageSource returns a types.ImageSource for the specified image reference.
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// The caller must call .Close() on the returned ImageSource.
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//
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// It would be great if we were able to stream the input tar as it is being
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// sent; but Docker sends the top-level manifest, which determines which paths
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// to look for, at the end, so in we will need to seek back and re-read, several times.
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// (We could, perhaps, expect an exact sequence, assume that the first plaintext file
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// is the config, and that the following len(RootFS) files are the layers, but that feels
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// way too brittle.)
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func newImageSource(ctx context.Context, sys *types.SystemContext, ref daemonReference) (private.ImageSource, error) {
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c, err := newDockerClient(sys)
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if err != nil {
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return nil, perrors.Wrap(err, "initializing docker engine client")
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}
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// Per NewReference(), ref.StringWithinTransport() is either an image ID (config digest), or a !reference.NameOnly() reference.
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// Either way ImageSave should create a tarball with exactly one image.
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inputStream, err := c.ImageSave(ctx, []string{ref.StringWithinTransport()})
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if err != nil {
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return nil, perrors.Wrap(err, "loading image from docker engine")
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}
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defer inputStream.Close()
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archive, err := tarfile.NewReaderFromStream(sys, inputStream)
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if err != nil {
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return nil, err
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}
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src := tarfile.NewSource(archive, true, ref.Transport().Name(), nil, -1)
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return &daemonImageSource{
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ref: ref,
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Source: src,
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}, nil
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}
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// Reference returns the reference used to set up this source, _as specified by the user_
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// (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.
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func (s *daemonImageSource) Reference() types.ImageReference {
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return s.ref
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}
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