fix: gc for untagged docker manifests (#3349)

- fixes #3347: removeUntaggedManifests() did not consider compatible manifest types
- add AsDockerImage() to Image and MultiarchImage for testing
- extend TestGarbageCollectAndRetentionMetaDB to test docker image and multiarch image

Signed-off-by: Stephan Merker <stephan.merker@sap.com>

pkg/test/image-utils/images.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"time"
 
+	docker "github.com/distribution/distribution/v3/manifest/schema2"
 	godigest "github.com/opencontainers/go-digest"
 	"github.com/opencontainers/image-spec/specs-go"
 	ispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -173,6 +174,35 @@ func (img Image) AsImageMeta() mTypes.ImageMeta {
 	}
 }
 
+func (img Image) AsDockerImage() Image {
+	// Convert manifest media type
+	img.Manifest.MediaType = docker.MediaTypeManifest
+
+	// Convert config media type
+	img.Manifest.Config.MediaType = docker.MediaTypeImageConfig
+	img.ConfigDescriptor.MediaType = docker.MediaTypeImageConfig
+
+	// Convert layer media types
+	for i := range img.Manifest.Layers {
+		img.Manifest.Layers[i].MediaType = docker.MediaTypeLayer
+	}
+
+	manifestBlob, err := json.Marshal(img.Manifest)
+	if err != nil {
+		panic("unreachable: ispec.Manifest should always be marshable")
+	}
+
+	img.ManifestDescriptor = ispec.Descriptor{
+		MediaType: docker.MediaTypeImageConfig,
+		Digest:    img.digestAlgorithm.FromBytes(manifestBlob),
+		Size:      int64(len(manifestBlob)),
+		Data:      manifestBlob,
+		Platform:  img.ConfigDescriptor.Platform,
+	}
+
+	return img
+}
+
 type Layer struct {
 	Blob      []byte
 	MediaType string

pkg/test/image-utils/images_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"testing"
 
+	docker "github.com/distribution/distribution/v3/manifest/schema2"
 	godigest "github.com/opencontainers/go-digest"
 	ispec "github.com/opencontainers/image-spec/specs-go/v1"
 	. "github.com/smartystreets/goconvey/convey"
@@ -197,3 +198,19 @@ func TestImageMethods(t *testing.T) {
 		})
 	})
 }
+
+func TestConvertImageToDocker(t *testing.T) {
+	Convey("AsDockerImage", t, func() {
+		Convey("DefaultImage", func() {
+			img := CreateDefaultImage()
+			dockerImage := img.AsDockerImage()
+
+			So(dockerImage.Manifest.MediaType, ShouldEqual, docker.MediaTypeManifest)
+			So(dockerImage.ConfigDescriptor.MediaType, ShouldEqual, docker.MediaTypeImageConfig)
+
+			for _, layer := range dockerImage.Manifest.Layers {
+				So(layer.MediaType, ShouldEqual, docker.MediaTypeLayer)
+			}
+		})
+	})
+}

pkg/test/image-utils/multiarch.go

@@ -3,6 +3,7 @@ package image
 import (
 	"encoding/json"
 
+	dockerList "github.com/distribution/distribution/v3/manifest/manifestlist"
 	godigest "github.com/opencontainers/go-digest"
 	"github.com/opencontainers/image-spec/specs-go"
 	ispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -75,6 +76,34 @@ func (mi MultiarchImage) AsImageMeta() mTypes.ImageMeta {
 	}
 }
 
+func (mi MultiarchImage) AsDockerImage() MultiarchImage {
+	for i := range mi.Images {
+		mi.Images[i] = mi.Images[i].AsDockerImage()
+	}
+
+	mi.Index.MediaType = dockerList.MediaTypeManifestList
+	for i := range mi.Index.Manifests {
+		mi.Index.Manifests[i].Digest = mi.Images[i].ManifestDescriptor.Digest
+		mi.Index.Manifests[i].Size = mi.Images[i].ManifestDescriptor.Size
+		mi.Index.Manifests[i].MediaType = mi.Images[i].ManifestDescriptor.MediaType
+	}
+
+	indexBlob, err := json.Marshal(mi.Index)
+	if err != nil {
+		panic("unreachable: ispec.Index should always be marshable")
+	}
+
+	mi.IndexDescriptor.MediaType = dockerList.MediaTypeManifestList
+	mi.IndexDescriptor = ispec.Descriptor{
+		MediaType: dockerList.MediaTypeManifestList,
+		Digest:    mi.digestAlgorithm.FromBytes(indexBlob),
+		Size:      int64(len(indexBlob)),
+		Data:      indexBlob,
+	}
+
+	return mi
+}
+
 type ImagesBuilder interface {
 	Images(images []Image) MultiarchBuilder
 	RandomImages(count int) MultiarchBuilder

pkg/test/image-utils/write.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 
 	godigest "github.com/opencontainers/go-digest"
-	ispec "github.com/opencontainers/image-spec/specs-go/v1"
 
 	stypes "zotregistry.dev/zot/pkg/storage/types"
 )
@@ -52,7 +51,7 @@ func WriteImageToFileSystem(image Image, repoName, ref string, storeController s
 		return err
 	}
 
-	_, _, err = store.PutImageManifest(repoName, ref, ispec.MediaTypeImageManifest, manifestBlob)
+	_, _, err = store.PutImageManifest(repoName, ref, image.Manifest.MediaType, manifestBlob)
 	if err != nil {
 		return err
 	}
@@ -82,7 +81,7 @@ func WriteMultiArchImageToFileSystem(multiarchImage MultiarchImage, repoName, re
 		return err
 	}
 
-	_, _, err = store.PutImageManifest(repoName, ref, ispec.MediaTypeImageIndex,
+	_, _, err = store.PutImageManifest(repoName, ref, multiarchImage.Index.MediaType,
 		indexBlob)
 
 	return err