artifact: only allow single manifest

Allowing for multiple manifest per artifact just makes the code and cli
design harder to work with it. It is not clear how mounting, extracting
or edit on a multi manifest artifact should have worked.

A single manifest should make the code much easier to work with.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

pkg/libartifact/artifact.go

@@ -11,17 +11,17 @@ import (
 )
 
 type Artifact struct {
-	Manifests []manifest.OCI1
-	Name      string
+	// Manifest is the OCI manifest for the artifact with the name.
+	// In a valid artifact the Manifest is guaranteed to not be nil.
+	Manifest *manifest.OCI1
+	Name     string
 }
 
 // TotalSizeBytes returns the total bytes of the all the artifact layers
 func (a *Artifact) TotalSizeBytes() int64 {
 	var s int64
-	for _, artifact := range a.Manifests {
-		for _, layer := range artifact.Layers {
-			s += layer.Size
-		}
+	for _, layer := range a.Manifest.Layers {
+		s += layer.Size
 	}
 	return s
 }
@@ -45,13 +45,7 @@ func (a *Artifact) SetName(name string) {
 }
 
 func (a *Artifact) GetDigest() (*digest.Digest, error) {
-	if len(a.Manifests) > 1 {
-		return nil, fmt.Errorf("not supported: multiple manifests found in artifact")
-	}
-	if len(a.Manifests) < 1 {
-		return nil, fmt.Errorf("not supported: no manifests found in artifact")
-	}
-	b, err := json.Marshal(a.Manifests[0])
+	b, err := json.Marshal(a.Manifest)
 	if err != nil {
 		return nil, err
 	}
@@ -72,17 +66,13 @@ func (al ArtifactList) GetByNameOrDigest(nameOrDigest string) (*Artifact, bool,
 	}
 	// Before giving up, check by digest
 	for _, artifact := range al {
-		// TODO Here we have to assume only a single manifest for the artifact; this will
-		// need to evolve
-		if len(artifact.Manifests) > 0 {
-			artifactDigest, err := artifact.GetDigest()
-			if err != nil {
-				return nil, false, err
-			}
-			// If the artifact's digest matches or is a prefix of ...
-			if artifactDigest.Encoded() == nameOrDigest || strings.HasPrefix(artifactDigest.Encoded(), nameOrDigest) {
-				return artifact, true, nil
-			}
+		artifactDigest, err := artifact.GetDigest()
+		if err != nil {
+			return nil, false, err
+		}
+		// If the artifact's digest matches or is a prefix of ...
+		if artifactDigest.Encoded() == nameOrDigest || strings.HasPrefix(artifactDigest.Encoded(), nameOrDigest) {
+			return artifact, true, nil
 		}
 	}
 	return nil, false, fmt.Errorf("no artifact found with name or digest of %s", nameOrDigest)

pkg/libartifact/store/store.go

@@ -299,13 +299,13 @@ func (as ArtifactStore) getArtifacts(ctx context.Context, _ *libartTypes.GetArti
 		if err != nil {
 			return nil, err
 		}
-		manifests, err := getManifests(ctx, imgSrc, nil)
+		manifest, err := getManifest(ctx, imgSrc)
 		imgSrc.Close()
 		if err != nil {
 			return nil, err
 		}
 		artifact := libartifact.Artifact{
-			Manifests: manifests,
+			Manifest: manifest,
 		}
 		if val, ok := l.ManifestDescriptor.Annotations[specV1.AnnotationRefName]; ok {
 			artifact.SetName(val)
@@ -316,41 +316,25 @@ func (as ArtifactStore) getArtifacts(ctx context.Context, _ *libartTypes.GetArti
 	return al, nil
 }
 
-// getManifests takes an imgSrc and starting digest (nil means "top") and collects all the manifests "under"
-// it.  this func calls itself recursively with a new startingDigest assuming that we are dealing with
-// an index list
-func getManifests(ctx context.Context, imgSrc types.ImageSource, startingDigest *digest.Digest) ([]manifest.OCI1, error) {
-	var (
-		manifests []manifest.OCI1
-	)
-	b, manifestType, err := imgSrc.GetManifest(ctx, startingDigest)
+// getManifest takes an imgSrc and returns the manifest for the imgSrc.
+// A OCI index list is not supported and will return an error.
+func getManifest(ctx context.Context, imgSrc types.ImageSource) (*manifest.OCI1, error) {
+	b, manifestType, err := imgSrc.GetManifest(ctx, nil)
 	if err != nil {
 		return nil, err
 	}
 
-	// this assumes that there are only single, and multi-images
-	if !manifest.MIMETypeIsMultiImage(manifestType) {
-		// these are the keepers
-		mani, err := manifest.OCI1FromManifest(b)
-		if err != nil {
-			return nil, err
-		}
-		manifests = append(manifests, *mani)
-		return manifests, nil
+	// We only support a single flat manifest and not an oci index list
+	if manifest.MIMETypeIsMultiImage(manifestType) {
+		return nil, fmt.Errorf("manifest %q is index list", imgSrc.Reference().StringWithinTransport())
 	}
-	// We are dealing with an oci index list
-	maniList, err := manifest.OCI1IndexFromManifest(b)
+
+	// parse the single manifest
+	mani, err := manifest.OCI1FromManifest(b)
 	if err != nil {
 		return nil, err
 	}
-	for _, m := range maniList.Manifests {
-		iterManifests, err := getManifests(ctx, imgSrc, &m.Digest)
-		if err != nil {
-			return nil, err
-		}
-		manifests = append(manifests, iterManifests...)
-	}
-	return manifests, nil
+	return mani, nil
 }
 
 func createEmptyStanza(path string) error {

test/e2e/artifact_test.go

@@ -94,9 +94,9 @@ var _ = Describe("Podman artifact", func() {
 		err = json.Unmarshal([]byte(inspectSingleSession.OutputToString()), &a)
 		Expect(err).ToNot(HaveOccurred())
 		Expect(a.Name).To(Equal(artifact1Name))
-		Expect(a.Manifests[0].ArtifactType).To(Equal(artifactType))
-		Expect(a.Manifests[0].Layers[0].Annotations["color"]).To(Equal("blue"))
-		Expect(a.Manifests[0].Layers[0].Annotations["flavor"]).To(Equal("lemon"))
+		Expect(a.Manifest.ArtifactType).To(Equal(artifactType))
+		Expect(a.Manifest.Layers[0].Annotations["color"]).To(Equal("blue"))
+		Expect(a.Manifest.Layers[0].Annotations["flavor"]).To(Equal("lemon"))
 
 		failSession := podmanTest.Podman([]string{"artifact", "add", "--annotation", "org.opencontainers.image.title=foobar", "foobar", artifact1File})
 		failSession.WaitWithDefaultTimeout()
@@ -122,11 +122,7 @@ var _ = Describe("Podman artifact", func() {
 		Expect(err).ToNot(HaveOccurred())
 		Expect(a.Name).To(Equal(artifact1Name))
 
-		var layerCount int
-		for _, layer := range a.Manifests {
-			layerCount += len(layer.Layers)
-		}
-		Expect(layerCount).To(Equal(2))
+		Expect(a.Manifest.Layers).To(HaveLen(2))
 	})
 
 	It("podman artifact push and pull", func() {