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Fix possibly incorrect media type default on import

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As reported, running import twice without using the compress import
option means that the content store will have existing layers during the
second import and the existing code hardcodes existing layer media type
to compressed. This fixes the issue by actually reading the header bytes
from the store and setting the media type appropriately.

Signed-off-by: Phil Estes <estesp@amazon.com>
This commit is contained in:
Phil Estes 2022-01-25 14:11:20 -05:00
parent 2986d5b077
commit 4aff7431fe
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GPG Key ID: FE2598126B196A38
1 changed files with 31 additions and 1 deletions
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32
images/archive/importer.go
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@ -269,9 +269,13 @@ func resolveLayers(ctx context.Context, store content.Store, layerFiles []string
if ok {
desc := descs[digest.Digest(dgst)]
if desc != nil {
desc.MediaType = images.MediaTypeDockerSchema2LayerGzip
desc.Digest = info.Digest
desc.Size = info.Size
mediaType, err := detectLayerMediaType(ctx, store, *desc)
if err != nil {
return fmt.Errorf("failed to detect media type of layer: %w", err)
}
desc.MediaType = mediaType
}
}
return nil
@ -381,3 +385,29 @@ func writeManifest(ctx context.Context, cs content.Ingester, manifest interface{
return desc, nil
}
func detectLayerMediaType(ctx context.Context, store content.Store, desc ocispec.Descriptor) (string, error) {
var mediaType string
// need to parse existing blob to use the proper media type
bytes := make([]byte, 10)
ra, err := store.ReaderAt(ctx, desc)
if err != nil {
return "", fmt.Errorf("failed to read content store to detect layer media type: %w", err)
}
defer ra.Close()
_, err = ra.ReadAt(bytes, 0)
if err != nil && err != io.EOF {
return "", fmt.Errorf("failed to read header bytes from layer to detect media type: %w", err)
}
if err == io.EOF {
// in the case of an empty layer then the media type should be uncompressed
return images.MediaTypeDockerSchema2Layer, nil
}
switch c := compression.DetectCompression(bytes); c {
case compression.Uncompressed:
mediaType = images.MediaTypeDockerSchema2Layer
default:
mediaType = images.MediaTypeDockerSchema2LayerGzip
}
return mediaType, nil
}