func (i *genericImage) getLayer(dest types.ImageDestination, digest string) error {
stream, _, err := i.src.GetBlob(digest)
if err != nil {
return err
}
defer stream.Close()
return dest.PutBlob(digest, stream)
}
// Based on docker/distribution/manifest/schema1/config_builder.go
func (m *manifestSchema2) convertToManifestSchema1(dest types.ImageDestination) (types.Image, error) {
configBytes, err := m.ConfigBlob()
if err != nil {
return nil, err
}
imageConfig := &image{}
if err := json.Unmarshal(configBytes, imageConfig); err != nil {
return nil, err
}
// Build fsLayers and History, discarding all configs. We will patch the top-level config in later.
fsLayers := make([]fsLayersSchema1, len(imageConfig.History))
history := make([]historySchema1, len(imageConfig.History))
nonemptyLayerIndex := 0
var parentV1ID string // Set in the loop
v1ID := ""
haveGzippedEmptyLayer := false
if len(imageConfig.History) == 0 {
// What would this even mean?! Anyhow, the rest of the code depends on fsLayers[0] and history[0] existing.
return nil, errors.Errorf("Cannot convert an image with 0 history entries to %s", manifest.DockerV2Schema1SignedMediaType)
}
for v2Index, historyEntry := range imageConfig.History {
parentV1ID = v1ID
v1Index := len(imageConfig.History) - 1 - v2Index
var blobDigest digest.Digest
if historyEntry.EmptyLayer {
if !haveGzippedEmptyLayer {
logrus.Debugf("Uploading empty layer during conversion to schema 1")
info, err := dest.PutBlob(bytes.NewReader(gzippedEmptyLayer), types.BlobInfo{Digest: gzippedEmptyLayerDigest, Size: int64(len(gzippedEmptyLayer))})
if err != nil {
return nil, errors.Wrap(err, "Error uploading empty layer")
}
if info.Digest != gzippedEmptyLayerDigest {
return nil, errors.Errorf("Internal error: Uploaded empty layer has digest %#v instead of %s", info.Digest, gzippedEmptyLayerDigest)
}
haveGzippedEmptyLayer = true
}
blobDigest = gzippedEmptyLayerDigest
} else {
if nonemptyLayerIndex >= len(m.LayersDescriptors) {
return nil, errors.Errorf("Invalid image configuration, needs more than the %d distributed layers", len(m.LayersDescriptors))
}
blobDigest = m.LayersDescriptors[nonemptyLayerIndex].Digest
nonemptyLayerIndex++
}
// AFAICT pull ignores these ID values, at least nowadays, so we could use anything unique, including a simple counter. Use what Docker uses for cargo-cult consistency.
v, err := v1IDFromBlobDigestAndComponents(blobDigest, parentV1ID)
if err != nil {
return nil, err
}
v1ID = v
fakeImage := v1Compatibility{
ID: v1ID,
Parent: parentV1ID,
Comment: historyEntry.Comment,
Created: historyEntry.Created,
Author: historyEntry.Author,
ThrowAway: historyEntry.EmptyLayer,
}
fakeImage.ContainerConfig.Cmd = []string{historyEntry.CreatedBy}
v1CompatibilityBytes, err := json.Marshal(&fakeImage)
if err != nil {
return nil, errors.Errorf("Internal error: Error creating v1compatibility for %#v", fakeImage)
}
fsLayers[v1Index] = fsLayersSchema1{BlobSum: blobDigest}
history[v1Index] = historySchema1{V1Compatibility: string(v1CompatibilityBytes)}
// Note that parentV1ID of the top layer is preserved when exiting this loop
}
// Now patch in real configuration for the top layer (v1Index == 0)
v1ID, err = v1IDFromBlobDigestAndComponents(fsLayers[0].BlobSum, parentV1ID, string(configBytes)) // See above WRT v1ID value generation and cargo-cult consistency.
if err != nil {
return nil, err
}
v1Config, err := v1ConfigFromConfigJSON(configBytes, v1ID, parentV1ID, imageConfig.History[len(imageConfig.History)-1].EmptyLayer)
if err != nil {
return nil, err
}
history[0].V1Compatibility = string(v1Config)
m1 := manifestSchema1FromComponents(dest.Reference().DockerReference(), fsLayers, history, imageConfig.Architecture)
return memoryImageFromManifest(m1), nil
}