chore: vendor

vendor/github.com/docker/distribution/manifest/doc.go

@@ -0,0 +1 @@
+package manifest

vendor/github.com/docker/distribution/manifest/manifestlist/manifestlist.go

@@ -0,0 +1,239 @@
+package manifestlist
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/manifest"
+	"github.com/opencontainers/go-digest"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+const (
+	// MediaTypeManifestList specifies the mediaType for manifest lists.
+	MediaTypeManifestList = "application/vnd.docker.distribution.manifest.list.v2+json"
+)
+
+// SchemaVersion provides a pre-initialized version structure for this
+// packages version of the manifest.
+var SchemaVersion = manifest.Versioned{
+	SchemaVersion: 2,
+	MediaType:     MediaTypeManifestList,
+}
+
+// OCISchemaVersion provides a pre-initialized version structure for this
+// packages OCIschema version of the manifest.
+var OCISchemaVersion = manifest.Versioned{
+	SchemaVersion: 2,
+	MediaType:     v1.MediaTypeImageIndex,
+}
+
+func init() {
+	manifestListFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+		m := new(DeserializedManifestList)
+		err := m.UnmarshalJSON(b)
+		if err != nil {
+			return nil, distribution.Descriptor{}, err
+		}
+
+		if m.MediaType != MediaTypeManifestList {
+			err = fmt.Errorf("mediaType in manifest list should be '%s' not '%s'",
+				MediaTypeManifestList, m.MediaType)
+
+			return nil, distribution.Descriptor{}, err
+		}
+
+		dgst := digest.FromBytes(b)
+		return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: MediaTypeManifestList}, err
+	}
+	err := distribution.RegisterManifestSchema(MediaTypeManifestList, manifestListFunc)
+	if err != nil {
+		panic(fmt.Sprintf("Unable to register manifest: %s", err))
+	}
+
+	imageIndexFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+		if err := validateIndex(b); err != nil {
+			return nil, distribution.Descriptor{}, err
+		}
+		m := new(DeserializedManifestList)
+		err := m.UnmarshalJSON(b)
+		if err != nil {
+			return nil, distribution.Descriptor{}, err
+		}
+
+		if m.MediaType != "" && m.MediaType != v1.MediaTypeImageIndex {
+			err = fmt.Errorf("if present, mediaType in image index should be '%s' not '%s'",
+				v1.MediaTypeImageIndex, m.MediaType)
+
+			return nil, distribution.Descriptor{}, err
+		}
+
+		dgst := digest.FromBytes(b)
+		return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: v1.MediaTypeImageIndex}, err
+	}
+	err = distribution.RegisterManifestSchema(v1.MediaTypeImageIndex, imageIndexFunc)
+	if err != nil {
+		panic(fmt.Sprintf("Unable to register OCI Image Index: %s", err))
+	}
+}
+
+// PlatformSpec specifies a platform where a particular image manifest is
+// applicable.
+type PlatformSpec struct {
+	// Architecture field specifies the CPU architecture, for example
+	// `amd64` or `ppc64`.
+	Architecture string `json:"architecture"`
+
+	// OS specifies the operating system, for example `linux` or `windows`.
+	OS string `json:"os"`
+
+	// OSVersion is an optional field specifying the operating system
+	// version, for example `10.0.10586`.
+	OSVersion string `json:"os.version,omitempty"`
+
+	// OSFeatures is an optional field specifying an array of strings,
+	// each listing a required OS feature (for example on Windows `win32k`).
+	OSFeatures []string `json:"os.features,omitempty"`
+
+	// Variant is an optional field specifying a variant of the CPU, for
+	// example `ppc64le` to specify a little-endian version of a PowerPC CPU.
+	Variant string `json:"variant,omitempty"`
+
+	// Features is an optional field specifying an array of strings, each
+	// listing a required CPU feature (for example `sse4` or `aes`).
+	Features []string `json:"features,omitempty"`
+}
+
+// A ManifestDescriptor references a platform-specific manifest.
+type ManifestDescriptor struct {
+	distribution.Descriptor
+
+	// Platform specifies which platform the manifest pointed to by the
+	// descriptor runs on.
+	Platform PlatformSpec `json:"platform"`
+}
+
+// ManifestList references manifests for various platforms.
+type ManifestList struct {
+	manifest.Versioned
+
+	// Config references the image configuration as a blob.
+	Manifests []ManifestDescriptor `json:"manifests"`
+}
+
+// References returns the distribution descriptors for the referenced image
+// manifests.
+func (m ManifestList) References() []distribution.Descriptor {
+	dependencies := make([]distribution.Descriptor, len(m.Manifests))
+	for i := range m.Manifests {
+		dependencies[i] = m.Manifests[i].Descriptor
+	}
+
+	return dependencies
+}
+
+// DeserializedManifestList wraps ManifestList with a copy of the original
+// JSON.
+type DeserializedManifestList struct {
+	ManifestList
+
+	// canonical is the canonical byte representation of the Manifest.
+	canonical []byte
+}
+
+// FromDescriptors takes a slice of descriptors, and returns a
+// DeserializedManifestList which contains the resulting manifest list
+// and its JSON representation.
+func FromDescriptors(descriptors []ManifestDescriptor) (*DeserializedManifestList, error) {
+	var mediaType string
+	if len(descriptors) > 0 && descriptors[0].Descriptor.MediaType == v1.MediaTypeImageManifest {
+		mediaType = v1.MediaTypeImageIndex
+	} else {
+		mediaType = MediaTypeManifestList
+	}
+
+	return FromDescriptorsWithMediaType(descriptors, mediaType)
+}
+
+// FromDescriptorsWithMediaType is for testing purposes, it's useful to be able to specify the media type explicitly
+func FromDescriptorsWithMediaType(descriptors []ManifestDescriptor, mediaType string) (*DeserializedManifestList, error) {
+	m := ManifestList{
+		Versioned: manifest.Versioned{
+			SchemaVersion: 2,
+			MediaType:     mediaType,
+		},
+	}
+
+	m.Manifests = make([]ManifestDescriptor, len(descriptors))
+	copy(m.Manifests, descriptors)
+
+	deserialized := DeserializedManifestList{
+		ManifestList: m,
+	}
+
+	var err error
+	deserialized.canonical, err = json.MarshalIndent(&m, "", "   ")
+	return &deserialized, err
+}
+
+// UnmarshalJSON populates a new ManifestList struct from JSON data.
+func (m *DeserializedManifestList) UnmarshalJSON(b []byte) error {
+	m.canonical = make([]byte, len(b))
+	// store manifest list in canonical
+	copy(m.canonical, b)
+
+	// Unmarshal canonical JSON into ManifestList object
+	var manifestList ManifestList
+	if err := json.Unmarshal(m.canonical, &manifestList); err != nil {
+		return err
+	}
+
+	m.ManifestList = manifestList
+
+	return nil
+}
+
+// MarshalJSON returns the contents of canonical. If canonical is empty,
+// marshals the inner contents.
+func (m *DeserializedManifestList) MarshalJSON() ([]byte, error) {
+	if len(m.canonical) > 0 {
+		return m.canonical, nil
+	}
+
+	return nil, errors.New("JSON representation not initialized in DeserializedManifestList")
+}
+
+// Payload returns the raw content of the manifest list. The contents can be
+// used to calculate the content identifier.
+func (m DeserializedManifestList) Payload() (string, []byte, error) {
+	var mediaType string
+	if m.MediaType == "" {
+		mediaType = v1.MediaTypeImageIndex
+	} else {
+		mediaType = m.MediaType
+	}
+
+	return mediaType, m.canonical, nil
+}
+
+// unknownDocument represents a manifest, manifest list, or index that has not
+// yet been validated
+type unknownDocument struct {
+	Config interface{} `json:"config,omitempty"`
+	Layers interface{} `json:"layers,omitempty"`
+}
+
+// validateIndex returns an error if the byte slice is invalid JSON or if it
+// contains fields that belong to a manifest
+func validateIndex(b []byte) error {
+	var doc unknownDocument
+	if err := json.Unmarshal(b, &doc); err != nil {
+		return err
+	}
+	if doc.Config != nil || doc.Layers != nil {
+		return errors.New("index: expected index but found manifest")
+	}
+	return nil
+}

vendor/github.com/docker/distribution/manifest/ocischema/builder.go

@@ -0,0 +1,107 @@
+package ocischema
+
+import (
+	"context"
+	"errors"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/manifest"
+	"github.com/opencontainers/go-digest"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// Builder is a type for constructing manifests.
+type Builder struct {
+	// bs is a BlobService used to publish the configuration blob.
+	bs distribution.BlobService
+
+	// configJSON references
+	configJSON []byte
+
+	// layers is a list of layer descriptors that gets built by successive
+	// calls to AppendReference.
+	layers []distribution.Descriptor
+
+	// Annotations contains arbitrary metadata relating to the targeted content.
+	annotations map[string]string
+
+	// For testing purposes
+	mediaType string
+}
+
+// NewManifestBuilder is used to build new manifests for the current schema
+// version. It takes a BlobService so it can publish the configuration blob
+// as part of the Build process, and annotations.
+func NewManifestBuilder(bs distribution.BlobService, configJSON []byte, annotations map[string]string) distribution.ManifestBuilder {
+	mb := &Builder{
+		bs:          bs,
+		configJSON:  make([]byte, len(configJSON)),
+		annotations: annotations,
+		mediaType:   v1.MediaTypeImageManifest,
+	}
+	copy(mb.configJSON, configJSON)
+
+	return mb
+}
+
+// SetMediaType assigns the passed mediatype or error if the mediatype is not a
+// valid media type for oci image manifests currently: "" or "application/vnd.oci.image.manifest.v1+json"
+func (mb *Builder) SetMediaType(mediaType string) error {
+	if mediaType != "" && mediaType != v1.MediaTypeImageManifest {
+		return errors.New("invalid media type for OCI image manifest")
+	}
+
+	mb.mediaType = mediaType
+	return nil
+}
+
+// Build produces a final manifest from the given references.
+func (mb *Builder) Build(ctx context.Context) (distribution.Manifest, error) {
+	m := Manifest{
+		Versioned: manifest.Versioned{
+			SchemaVersion: 2,
+			MediaType:     mb.mediaType,
+		},
+		Layers:      make([]distribution.Descriptor, len(mb.layers)),
+		Annotations: mb.annotations,
+	}
+	copy(m.Layers, mb.layers)
+
+	configDigest := digest.FromBytes(mb.configJSON)
+
+	var err error
+	m.Config, err = mb.bs.Stat(ctx, configDigest)
+	switch err {
+	case nil:
+		// Override MediaType, since Put always replaces the specified media
+		// type with application/octet-stream in the descriptor it returns.
+		m.Config.MediaType = v1.MediaTypeImageConfig
+		return FromStruct(m)
+	case distribution.ErrBlobUnknown:
+		// nop
+	default:
+		return nil, err
+	}
+
+	// Add config to the blob store
+	m.Config, err = mb.bs.Put(ctx, v1.MediaTypeImageConfig, mb.configJSON)
+	// Override MediaType, since Put always replaces the specified media
+	// type with application/octet-stream in the descriptor it returns.
+	m.Config.MediaType = v1.MediaTypeImageConfig
+	if err != nil {
+		return nil, err
+	}
+
+	return FromStruct(m)
+}
+
+// AppendReference adds a reference to the current ManifestBuilder.
+func (mb *Builder) AppendReference(d distribution.Describable) error {
+	mb.layers = append(mb.layers, d.Descriptor())
+	return nil
+}
+
+// References returns the current references added to this builder.
+func (mb *Builder) References() []distribution.Descriptor {
+	return mb.layers
+}

vendor/github.com/docker/distribution/manifest/ocischema/manifest.go

@@ -0,0 +1,146 @@
+package ocischema
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/manifest"
+	"github.com/opencontainers/go-digest"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+var (
+	// SchemaVersion provides a pre-initialized version structure for this
+	// packages version of the manifest.
+	SchemaVersion = manifest.Versioned{
+		SchemaVersion: 2, // historical value here.. does not pertain to OCI or docker version
+		MediaType:     v1.MediaTypeImageManifest,
+	}
+)
+
+func init() {
+	ocischemaFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+		if err := validateManifest(b); err != nil {
+			return nil, distribution.Descriptor{}, err
+		}
+		m := new(DeserializedManifest)
+		err := m.UnmarshalJSON(b)
+		if err != nil {
+			return nil, distribution.Descriptor{}, err
+		}
+
+		dgst := digest.FromBytes(b)
+		return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: v1.MediaTypeImageManifest}, err
+	}
+	err := distribution.RegisterManifestSchema(v1.MediaTypeImageManifest, ocischemaFunc)
+	if err != nil {
+		panic(fmt.Sprintf("Unable to register manifest: %s", err))
+	}
+}
+
+// Manifest defines a ocischema manifest.
+type Manifest struct {
+	manifest.Versioned
+
+	// Config references the image configuration as a blob.
+	Config distribution.Descriptor `json:"config"`
+
+	// Layers lists descriptors for the layers referenced by the
+	// configuration.
+	Layers []distribution.Descriptor `json:"layers"`
+
+	// Annotations contains arbitrary metadata for the image manifest.
+	Annotations map[string]string `json:"annotations,omitempty"`
+}
+
+// References returns the descriptors of this manifests references.
+func (m Manifest) References() []distribution.Descriptor {
+	references := make([]distribution.Descriptor, 0, 1+len(m.Layers))
+	references = append(references, m.Config)
+	references = append(references, m.Layers...)
+	return references
+}
+
+// Target returns the target of this manifest.
+func (m Manifest) Target() distribution.Descriptor {
+	return m.Config
+}
+
+// DeserializedManifest wraps Manifest with a copy of the original JSON.
+// It satisfies the distribution.Manifest interface.
+type DeserializedManifest struct {
+	Manifest
+
+	// canonical is the canonical byte representation of the Manifest.
+	canonical []byte
+}
+
+// FromStruct takes a Manifest structure, marshals it to JSON, and returns a
+// DeserializedManifest which contains the manifest and its JSON representation.
+func FromStruct(m Manifest) (*DeserializedManifest, error) {
+	var deserialized DeserializedManifest
+	deserialized.Manifest = m
+
+	var err error
+	deserialized.canonical, err = json.MarshalIndent(&m, "", "   ")
+	return &deserialized, err
+}
+
+// UnmarshalJSON populates a new Manifest struct from JSON data.
+func (m *DeserializedManifest) UnmarshalJSON(b []byte) error {
+	m.canonical = make([]byte, len(b))
+	// store manifest in canonical
+	copy(m.canonical, b)
+
+	// Unmarshal canonical JSON into Manifest object
+	var manifest Manifest
+	if err := json.Unmarshal(m.canonical, &manifest); err != nil {
+		return err
+	}
+
+	if manifest.MediaType != "" && manifest.MediaType != v1.MediaTypeImageManifest {
+		return fmt.Errorf("if present, mediaType in manifest should be '%s' not '%s'",
+			v1.MediaTypeImageManifest, manifest.MediaType)
+	}
+
+	m.Manifest = manifest
+
+	return nil
+}
+
+// MarshalJSON returns the contents of canonical. If canonical is empty,
+// marshals the inner contents.
+func (m *DeserializedManifest) MarshalJSON() ([]byte, error) {
+	if len(m.canonical) > 0 {
+		return m.canonical, nil
+	}
+
+	return nil, errors.New("JSON representation not initialized in DeserializedManifest")
+}
+
+// Payload returns the raw content of the manifest. The contents can be used to
+// calculate the content identifier.
+func (m DeserializedManifest) Payload() (string, []byte, error) {
+	return v1.MediaTypeImageManifest, m.canonical, nil
+}
+
+// unknownDocument represents a manifest, manifest list, or index that has not
+// yet been validated
+type unknownDocument struct {
+	Manifests interface{} `json:"manifests,omitempty"`
+}
+
+// validateManifest returns an error if the byte slice is invalid JSON or if it
+// contains fields that belong to a index
+func validateManifest(b []byte) error {
+	var doc unknownDocument
+	if err := json.Unmarshal(b, &doc); err != nil {
+		return err
+	}
+	if doc.Manifests != nil {
+		return errors.New("ocimanifest: expected manifest but found index")
+	}
+	return nil
+}

vendor/github.com/docker/distribution/manifest/schema2/builder.go

@@ -0,0 +1,85 @@
+package schema2
+
+import (
+	"context"
+
+	"github.com/docker/distribution"
+	"github.com/opencontainers/go-digest"
+)
+
+// builder is a type for constructing manifests.
+type builder struct {
+	// bs is a BlobService used to publish the configuration blob.
+	bs distribution.BlobService
+
+	// configMediaType is media type used to describe configuration
+	configMediaType string
+
+	// configJSON references
+	configJSON []byte
+
+	// dependencies is a list of descriptors that gets built by successive
+	// calls to AppendReference. In case of image configuration these are layers.
+	dependencies []distribution.Descriptor
+}
+
+// NewManifestBuilder is used to build new manifests for the current schema
+// version. It takes a BlobService so it can publish the configuration blob
+// as part of the Build process.
+func NewManifestBuilder(bs distribution.BlobService, configMediaType string, configJSON []byte) distribution.ManifestBuilder {
+	mb := &builder{
+		bs:              bs,
+		configMediaType: configMediaType,
+		configJSON:      make([]byte, len(configJSON)),
+	}
+	copy(mb.configJSON, configJSON)
+
+	return mb
+}
+
+// Build produces a final manifest from the given references.
+func (mb *builder) Build(ctx context.Context) (distribution.Manifest, error) {
+	m := Manifest{
+		Versioned: SchemaVersion,
+		Layers:    make([]distribution.Descriptor, len(mb.dependencies)),
+	}
+	copy(m.Layers, mb.dependencies)
+
+	configDigest := digest.FromBytes(mb.configJSON)
+
+	var err error
+	m.Config, err = mb.bs.Stat(ctx, configDigest)
+	switch err {
+	case nil:
+		// Override MediaType, since Put always replaces the specified media
+		// type with application/octet-stream in the descriptor it returns.
+		m.Config.MediaType = mb.configMediaType
+		return FromStruct(m)
+	case distribution.ErrBlobUnknown:
+		// nop
+	default:
+		return nil, err
+	}
+
+	// Add config to the blob store
+	m.Config, err = mb.bs.Put(ctx, mb.configMediaType, mb.configJSON)
+	// Override MediaType, since Put always replaces the specified media
+	// type with application/octet-stream in the descriptor it returns.
+	m.Config.MediaType = mb.configMediaType
+	if err != nil {
+		return nil, err
+	}
+
+	return FromStruct(m)
+}
+
+// AppendReference adds a reference to the current ManifestBuilder.
+func (mb *builder) AppendReference(d distribution.Describable) error {
+	mb.dependencies = append(mb.dependencies, d.Descriptor())
+	return nil
+}
+
+// References returns the current references added to this builder.
+func (mb *builder) References() []distribution.Descriptor {
+	return mb.dependencies
+}

vendor/github.com/docker/distribution/manifest/schema2/manifest.go

@@ -0,0 +1,144 @@
+package schema2
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/manifest"
+	"github.com/opencontainers/go-digest"
+)
+
+const (
+	// MediaTypeManifest specifies the mediaType for the current version.
+	MediaTypeManifest = "application/vnd.docker.distribution.manifest.v2+json"
+
+	// MediaTypeImageConfig specifies the mediaType for the image configuration.
+	MediaTypeImageConfig = "application/vnd.docker.container.image.v1+json"
+
+	// MediaTypePluginConfig specifies the mediaType for plugin configuration.
+	MediaTypePluginConfig = "application/vnd.docker.plugin.v1+json"
+
+	// MediaTypeLayer is the mediaType used for layers referenced by the
+	// manifest.
+	MediaTypeLayer = "application/vnd.docker.image.rootfs.diff.tar.gzip"
+
+	// MediaTypeForeignLayer is the mediaType used for layers that must be
+	// downloaded from foreign URLs.
+	MediaTypeForeignLayer = "application/vnd.docker.image.rootfs.foreign.diff.tar.gzip"
+
+	// MediaTypeUncompressedLayer is the mediaType used for layers which
+	// are not compressed.
+	MediaTypeUncompressedLayer = "application/vnd.docker.image.rootfs.diff.tar"
+)
+
+var (
+	// SchemaVersion provides a pre-initialized version structure for this
+	// packages version of the manifest.
+	SchemaVersion = manifest.Versioned{
+		SchemaVersion: 2,
+		MediaType:     MediaTypeManifest,
+	}
+)
+
+func init() {
+	schema2Func := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+		m := new(DeserializedManifest)
+		err := m.UnmarshalJSON(b)
+		if err != nil {
+			return nil, distribution.Descriptor{}, err
+		}
+
+		dgst := digest.FromBytes(b)
+		return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: MediaTypeManifest}, err
+	}
+	err := distribution.RegisterManifestSchema(MediaTypeManifest, schema2Func)
+	if err != nil {
+		panic(fmt.Sprintf("Unable to register manifest: %s", err))
+	}
+}
+
+// Manifest defines a schema2 manifest.
+type Manifest struct {
+	manifest.Versioned
+
+	// Config references the image configuration as a blob.
+	Config distribution.Descriptor `json:"config"`
+
+	// Layers lists descriptors for the layers referenced by the
+	// configuration.
+	Layers []distribution.Descriptor `json:"layers"`
+}
+
+// References returns the descriptors of this manifests references.
+func (m Manifest) References() []distribution.Descriptor {
+	references := make([]distribution.Descriptor, 0, 1+len(m.Layers))
+	references = append(references, m.Config)
+	references = append(references, m.Layers...)
+	return references
+}
+
+// Target returns the target of this manifest.
+func (m Manifest) Target() distribution.Descriptor {
+	return m.Config
+}
+
+// DeserializedManifest wraps Manifest with a copy of the original JSON.
+// It satisfies the distribution.Manifest interface.
+type DeserializedManifest struct {
+	Manifest
+
+	// canonical is the canonical byte representation of the Manifest.
+	canonical []byte
+}
+
+// FromStruct takes a Manifest structure, marshals it to JSON, and returns a
+// DeserializedManifest which contains the manifest and its JSON representation.
+func FromStruct(m Manifest) (*DeserializedManifest, error) {
+	var deserialized DeserializedManifest
+	deserialized.Manifest = m
+
+	var err error
+	deserialized.canonical, err = json.MarshalIndent(&m, "", "   ")
+	return &deserialized, err
+}
+
+// UnmarshalJSON populates a new Manifest struct from JSON data.
+func (m *DeserializedManifest) UnmarshalJSON(b []byte) error {
+	m.canonical = make([]byte, len(b))
+	// store manifest in canonical
+	copy(m.canonical, b)
+
+	// Unmarshal canonical JSON into Manifest object
+	var manifest Manifest
+	if err := json.Unmarshal(m.canonical, &manifest); err != nil {
+		return err
+	}
+
+	if manifest.MediaType != MediaTypeManifest {
+		return fmt.Errorf("mediaType in manifest should be '%s' not '%s'",
+			MediaTypeManifest, manifest.MediaType)
+
+	}
+
+	m.Manifest = manifest
+
+	return nil
+}
+
+// MarshalJSON returns the contents of canonical. If canonical is empty,
+// marshals the inner contents.
+func (m *DeserializedManifest) MarshalJSON() ([]byte, error) {
+	if len(m.canonical) > 0 {
+		return m.canonical, nil
+	}
+
+	return nil, errors.New("JSON representation not initialized in DeserializedManifest")
+}
+
+// Payload returns the raw content of the manifest. The contents can be used to
+// calculate the content identifier.
+func (m DeserializedManifest) Payload() (string, []byte, error) {
+	return m.MediaType, m.canonical, nil
+}

vendor/github.com/docker/distribution/manifest/versioned.go

@@ -0,0 +1,12 @@
+package manifest
+
+// Versioned provides a struct with the manifest schemaVersion and mediaType.
+// Incoming content with unknown schema version can be decoded against this
+// struct to check the version.
+type Versioned struct {
+	// SchemaVersion is the image manifest schema that this image follows
+	SchemaVersion int `json:"schemaVersion"`
+
+	// MediaType is the media type of this schema.
+	MediaType string `json:"mediaType,omitempty"`
+}