fix(pusher): retrieve only the index and not all the layers

Fetch only the index data instead of the full graph pointed by the index
which is what the copy function in ORAS does. Using the FetchReference function
instead.

Signed-off-by: Aldo Lacuku <[email protected]>
Co-authored-by: Lorenzo Susini <[email protected]>

Author: 2 people

pkg/oci/pusher/pusher.go

@@ -30,7 +30,6 @@ import (
 	logger "github.com/sirupsen/logrus"
 	"oras.land/oras-go/v2"
 	"oras.land/oras-go/v2/content/file"
-	"oras.land/oras-go/v2/content/memory"
 	"oras.land/oras-go/v2/registry/remote"
 	"oras.land/oras-go/v2/registry/remote/auth"
 
@@ -112,9 +111,8 @@ func (p *Pusher) retrieveIndex(ctx context.Context, repo *remote.Repository) (*v
 	var indexBytes []byte
 	var index v1.Index
 
-	memoryStore := memory.New()
 	ref := repo.Reference.String()
-	indexDesc, err := oras.Copy(ctx, repo, repo.Reference.Reference, memoryStore, "", oras.DefaultCopyOptions)
+	indexDesc, reader, err := repo.FetchReference(ctx, repo.Reference.Reference)
 	if err != nil {
 		if strings.Contains(err.Error(), fmt.Sprintf("%s: not found", repo.Reference.Reference)) {
 			return nil, fmt.Errorf("unable to download image index for ref %s, %w", ref, ErrNotFound)
@@ -128,11 +126,6 @@ func (p *Pusher) retrieveIndex(ctx context.Context, repo *remote.Repository) (*v
 			ref, indexDesc.MediaType, v1.MediaTypeImageIndex)
 	}
 
-	reader, err := memoryStore.Fetch(ctx, indexDesc)
-	if err != nil {
-		return nil, fmt.Errorf("unable to fetch index from memory store for ref %q: %w", ref, err)
-	}
-
 	if indexBytes, err = io.ReadAll(reader); err != nil {
 		return nil, fmt.Errorf("unable to read index from reader for ref %q: %w", ref, err)
 	}