export: Copy distribution source labels to manifest annotations

vvoland · vvoland · commit abb3c5ef9431 · 2024-01-03T16:08:16.000+01:00
Persist manifest/indexes distribution source labels as annotations in the index.json. This could allow the importer to fetch the missing blobs from the external repository. These can't really be persisted directly in blob descriptors because that would alter the digests. Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com> (cherry picked from commit b9af453) Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
diff --git a/images/archive/exporter.go b/images/archive/exporter.go
@@ -24,11 +24,14 @@ import (
 	"io"
 	"path"
 	"sort"
+	"strings"
 
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/labels"
 	"github.com/containerd/containerd/platforms"
+	"github.com/containerd/log"
 	digest "github.com/opencontainers/go-digest"
 	ocispecs "github.com/opencontainers/image-spec/specs-go"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -191,6 +194,23 @@ func addNameAnnotation(name string, base map[string]string) map[string]string {
 	return annotations
 }
 
+func copySourceLabels(ctx context.Context, infoProvider content.InfoProvider, desc ocispec.Descriptor) (ocispec.Descriptor, error) {
+	info, err := infoProvider.Info(ctx, desc.Digest)
+	if err != nil {
+		return desc, err
+	}
+	for k, v := range info.Labels {
+		if strings.HasPrefix(k, labels.LabelDistributionSource) {
+			if desc.Annotations == nil {
+				desc.Annotations = map[string]string{k: v}
+			} else {
+				desc.Annotations[k] = v
+			}
+		}
+	}
+	return desc, nil
+}
+
 // ContentProvider provides both content and info about content
 type ContentProvider interface {
 	content.Provider
@@ -208,13 +228,22 @@ func Export(ctx context.Context, store ContentProvider, writer io.Writer, opts .
 
 	records := []tarRecord{
 		ociLayoutFile(""),
-		ociIndexRecord(eo.manifests),
+	}
+
+	manifests := make([]ocispec.Descriptor, 0, len(eo.manifests))
+	for _, desc := range eo.manifests {
+		d, err := copySourceLabels(ctx, store, desc)
+		if err != nil {
+			log.G(ctx).WithError(err).WithField("desc", desc).Warn("failed to copy distribution.source labels")
+			continue
+		}
+		manifests = append(manifests, d)
 	}
 
 	algorithms := map[string]struct{}{}
 	dManifests := map[digest.Digest]*exportManifest{}
 	resolvedIndex := map[digest.Digest]digest.Digest{}
-	for _, desc := range eo.manifests {
+	for _, desc := range manifests {
 		if images.IsManifestType(desc.MediaType) {
 			mt, ok := dManifests[desc.Digest]
 			if !ok {
@@ -304,6 +333,8 @@ func Export(ctx context.Context, store ContentProvider, writer io.Writer, opts .
 		}
 	}
 
+	records = append(records, ociIndexRecord(manifests))
+
 	if !eo.skipDockerManifest && len(dManifests) > 0 {
 		tr, err := manifestsRecord(ctx, store, dManifests)
 		if err != nil {
