manifest_list: inspect should contain formats OCIv1 and docker

ManifestInspect should contain all known formats for a valid manifest
list as of now only supported formats are `OCIv1` and `Docker` so
inspect should support that.

Example output from podman
```console
podman manifest inspect test
{
    "ociv1": {
        "schemaVersion": 2,
        "mediaType": "application/vnd.oci.image.index.v1+json",
        "manifests": [
            {
                "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                "digest": "sha256:9b2a28eb47540823042a2ba401386845089bb7b62a9637d55816132c4c3c36eb",
                "size": 528,
                "annotations": {
                    "annotationTest1": "annotationTest2"
                },
                "platform": {
                    "architecture": "amd64",
                    "os": "linux"
                }
            }
        ]
    },
    "docker": {
        "schemaVersion": 2,
        "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
        "manifests": [
            {
                "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
                "size": 528,
                "digest": "sha256:9b2a28eb47540823042a2ba401386845089bb7b62a9637d55816132c4c3c36eb",
                "platform": {
                    "architecture": "amd64",
                    "os": "linux"
                }
            }
        ]
    }
}
```

Closes: containers/podman#15069

Signed-off-by: Aditya R <[email protected]>

libimage/manifest_list.go

@@ -14,6 +14,7 @@ import (
 	"github.com/containers/image/v5/types"
 	"github.com/containers/storage"
 	"github.com/opencontainers/go-digest"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 // NOTE: the abstractions and APIs here are a first step to further merge
@@ -39,6 +40,12 @@ type ManifestList struct {
 	list manifests.List
 }
 
+// Manifest metadata, spec and settings, in multiple formats.
+type ManifestInspectReport struct {
+	OCIv1  *v1.Index             `json:"ociv1,omitempty"`
+	Docker *manifest.Schema2List `json:"docker,omitempty"`
+}
+
 // ID returns the ID of the manifest list.
 func (m *ManifestList) ID() string {
 	return m.image.ID()
@@ -210,8 +217,8 @@ func (i *Image) IsManifestList(ctx context.Context) (bool, error) {
 }
 
 // Inspect returns a dockerized version of the manifest list.
-func (m *ManifestList) Inspect() (*manifest.Schema2List, error) {
-	return m.list.Docker(), nil
+func (m *ManifestList) Inspect() (ManifestInspectReport, error) {
+	return ManifestInspectReport{m.list.OCIv1(), m.list.Docker()}, nil
 }
 
 // Options for adding a manifest list.

libimage/manifest_list_test.go

@@ -39,6 +39,36 @@ func TestCreateManifestList(t *testing.T) {
 	require.True(t, errors.Is(err, ErrNotAManifestList))
 }
 
+// Inspect must contain both formats i.e OCIv1 and docker
+func TestCreateAndInspectManifestListt(t *testing.T) {
+	listName := "testInspect"
+	runtime, cleanup := testNewRuntime(t)
+	defer cleanup()
+	ctx := context.Background()
+
+	list, err := runtime.CreateManifestList(listName)
+	require.NoError(t, err)
+	require.NotNil(t, list)
+
+	manifestListOpts := &ManifestListAddOptions{All: true}
+	_, err = list.Add(ctx, "docker://busybox", manifestListOpts)
+	require.NoError(t, err)
+
+	list, err = runtime.LookupManifestList(listName)
+	require.NoError(t, err)
+	require.NotNil(t, list)
+
+	inspectReport, err := list.Inspect()
+	require.NoError(t, err)
+	require.NotNil(t, inspectReport)
+
+	inspectReportJSON, err := json.Marshal(inspectReport)
+	require.NoError(t, err)
+	inspectReportString := string(inspectReportJSON)
+	require.Contains(t, inspectReportString, "ociv1")
+	require.Contains(t, inspectReportString, "docker")
+}
+
 // Following test ensure that `Tag` tags the manifest list instead of resolved image.
 // Both the tags should point to same image id
 func TestCreateAndTagManifestList(t *testing.T) {