enable docker load for hauler tarballs (#320)

- fixes #276

Signed-off-by: Jacob Blain Christen <jacob.blain.christen@ranchergovernment.com>
Co-authored-by: Zack Brady <zackbrady123@gmail.com>

cmd/hauler/cli/store/save.go

@@ -1,13 +1,25 @@
 package store
 
 import (
+	"bytes"
 	"context"
+	"encoding/json"
 	"os"
+	"path"
 	"path/filepath"
+	"slices"
 
+	referencev3 "github.com/distribution/distribution/v3/reference"
+	"github.com/google/go-containerregistry/pkg/name"
+	libv1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
+	"github.com/google/go-containerregistry/pkg/v1/types"
 	"github.com/mholt/archiver/v3"
+	imagev1 "github.com/opencontainers/image-spec/specs-go/v1"
 
 	"hauler.dev/go/hauler/internal/flags"
+	"hauler.dev/go/hauler/pkg/consts"
 	"hauler.dev/go/hauler/pkg/log"
 )
 
@@ -34,6 +46,10 @@ func SaveCmd(ctx context.Context, o *flags.SaveOpts, outputFile string) error {
 		return err
 	}
 
+	if err := writeExportsManifest(ctx, "."); err != nil {
+		return err
+	}
+
 	err = a.Archive([]string{"."}, absOutputfile)
 	if err != nil {
 		return err
@@ -42,3 +58,154 @@ func SaveCmd(ctx context.Context, o *flags.SaveOpts, outputFile string) error {
 	l.Infof("saved store [%s] -> [%s]", o.StoreDir, absOutputfile)
 	return nil
 }
+
+type exports struct {
+	digests []string
+	records map[string]tarball.Descriptor
+}
+
+func writeExportsManifest(ctx context.Context, dir string) error {
+	l := log.FromContext(ctx)
+
+	oci, err := layout.FromPath(dir)
+	if err != nil {
+		return err
+	}
+
+	idx, err := oci.ImageIndex()
+	if err != nil {
+		return err
+	}
+
+	imx, err := idx.IndexManifest()
+	if err != nil {
+		return err
+	}
+
+	x := &exports{
+		digests: []string{},
+		records: map[string]tarball.Descriptor{},
+	}
+
+	for _, desc := range imx.Manifests {
+		l.Debugf("descriptor [%s] >>> %s", desc.Digest.String(), desc.MediaType)
+		if artifactType := types.MediaType(desc.ArtifactType); artifactType != "" && !artifactType.IsImage() && !artifactType.IsIndex() {
+			l.Debugf("descriptor [%s] <<< SKIPPING ARTIFACT (%q)", desc.Digest.String(), desc.ArtifactType)
+			continue
+		}
+		if desc.Annotations != nil {
+			// we only care about images that cosign has added to the layout index
+			if kind, hasKind := desc.Annotations[consts.KindAnnotationName]; hasKind {
+				if refName, hasRefName := desc.Annotations[imagev1.AnnotationRefName]; hasRefName {
+					// branch on image (aka image manifest) or image index
+					switch kind {
+					case consts.KindAnnotationImage:
+						if err := x.record(ctx, idx, desc, refName); err != nil {
+							return err
+						}
+					case consts.KindAnnotationIndex:
+						l.Debugf("index [%s]: digest=%s, type=%s, size=%d", refName, desc.Digest.String(), desc.MediaType, desc.Size)
+						iix, err := idx.ImageIndex(desc.Digest)
+						if err != nil {
+							return err
+						}
+						ixm, err := iix.IndexManifest()
+						if err != nil {
+							return err
+						}
+						for _, ixd := range ixm.Manifests {
+							if ixd.MediaType.IsImage() {
+								if err := x.record(ctx, iix, ixd, refName); err != nil {
+									return err
+								}
+							}
+						}
+					default:
+						l.Debugf("descriptor [%s] <<< SKIPPING KIND (%q)", desc.Digest.String(), kind)
+					}
+				}
+			}
+		}
+	}
+
+	buf := bytes.Buffer{}
+	mnf := x.describe()
+	err = json.NewEncoder(&buf).Encode(mnf)
+	if err != nil {
+		return err
+	}
+
+	return oci.WriteFile("manifest.json", buf.Bytes(), 0666)
+}
+
+func (x *exports) describe() tarball.Manifest {
+	m := make(tarball.Manifest, len(x.digests))
+	for i, d := range x.digests {
+		m[i] = x.records[d]
+	}
+	return m
+}
+
+func (x *exports) record(ctx context.Context, index libv1.ImageIndex, desc libv1.Descriptor, refname string) error {
+	l := log.FromContext(ctx)
+
+	digest := desc.Digest.String()
+	image, err := index.Image(desc.Digest)
+	if err != nil {
+		return err
+	}
+
+	config, err := image.ConfigName()
+	if err != nil {
+		return err
+	}
+
+	xd, recorded := x.records[digest]
+	if !recorded {
+		// record one export record per digest
+		x.digests = append(x.digests, digest)
+		xd = tarball.Descriptor{
+			Config:   path.Join(imagev1.ImageBlobsDir, config.Algorithm, config.Hex),
+			RepoTags: []string{},
+			Layers:   []string{},
+		}
+
+		layers, err := image.Layers()
+		if err != nil {
+			return err
+		}
+		for _, layer := range layers {
+			xl, err := layer.Digest()
+			if err != nil {
+				return err
+			}
+			xd.Layers = append(xd.Layers[:], path.Join(imagev1.ImageBlobsDir, xl.Algorithm, xl.Hex))
+		}
+	}
+
+	ref, err := name.ParseReference(refname)
+	if err != nil {
+		return err
+	}
+
+	// record tags for the digest, eliminating dupes
+	switch tag := ref.(type) {
+	case name.Tag:
+		named, err := referencev3.ParseNormalizedNamed(refname)
+		if err != nil {
+			return err
+		}
+		named = referencev3.TagNameOnly(named)
+		repotag := referencev3.FamiliarString(named)
+		xd.RepoTags = append(xd.RepoTags[:], repotag)
+		slices.Sort(xd.RepoTags)
+		xd.RepoTags = slices.Compact(xd.RepoTags)
+		ref = tag.Digest(digest)
+	}
+
+	l.Debugf("image [%s]: type=%s, size=%d", ref.Name(), desc.MediaType, desc.Size)
+	// record export descriptor for the digest
+	x.records[digest] = xd
+
+	return nil
+}

pkg/consts/consts.go

@@ -47,8 +47,9 @@ const (
 	HaulerVendorPrefix = "vnd.hauler"
 	OCIImageIndexFile  = "index.json"
 
-	KindAnnotationName = "kind"
-	KindAnnotation     = "dev.cosignproject.cosign/image"
+	KindAnnotationName  = "kind"
+	KindAnnotationImage = "dev.cosignproject.cosign/image"
+	KindAnnotationIndex = "dev.cosignproject.cosign/imageIndex"
 
 	CarbideRegistry         = "rgcrprod.azurecr.us"
 	ImageAnnotationKey      = "hauler.dev/key"

pkg/content/oci.go

@@ -124,9 +124,9 @@ func (o *OCI) SaveIndex() error {
 		kindJ := descs[j].Annotations["kind"]
 
 		// Objects with the prefix of "dev.cosignproject.cosign/image" should be at the top.
-		if strings.HasPrefix(kindI, consts.KindAnnotation) && !strings.HasPrefix(kindJ, consts.KindAnnotation) {
+		if strings.HasPrefix(kindI, consts.KindAnnotationImage) && !strings.HasPrefix(kindJ, consts.KindAnnotationImage) {
 			return true
-		} else if !strings.HasPrefix(kindI, consts.KindAnnotation) && strings.HasPrefix(kindJ, consts.KindAnnotation) {
+		} else if !strings.HasPrefix(kindI, consts.KindAnnotationImage) && strings.HasPrefix(kindJ, consts.KindAnnotationImage) {
 			return false
 		}
 		return false // Default: maintain the order.

pkg/store/store.go

@@ -118,7 +118,7 @@ func (l *Layout) AddOCI(ctx context.Context, oci artifacts.OCI, ref string) (oci
 		Digest:    digest.FromBytes(mdata),
 		Size:      int64(len(mdata)),
 		Annotations: map[string]string{
-			consts.KindAnnotationName: consts.KindAnnotation,
+			consts.KindAnnotationName: consts.KindAnnotationImage,
 			ocispec.AnnotationRefName: ref,
 		},
 		URLs:     nil,