distribution/manifest/ocischema/index.go

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package ocischema
import (
"encoding/json"
"errors"
"fmt"
"github.com/distribution/distribution/v3"
"github.com/distribution/distribution/v3/manifest"
"github.com/opencontainers/go-digest"
v1 "github.com/opencontainers/image-spec/specs-go/v1"
)
// IndexSchemaVersion provides a pre-initialized version structure for OCI Image
// Indices.
var IndexSchemaVersion = manifest.Versioned{
SchemaVersion: 2,
MediaType: v1.MediaTypeImageIndex,
}
func init() {
imageIndexFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
if err := validateIndex(b); err != nil {
return nil, distribution.Descriptor{}, err
}
m := new(DeserializedImageIndex)
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))
}
}
// ImageIndex references manifests for various platforms.
type ImageIndex struct {
manifest.Versioned
// Manifests references a list of manifests
Manifests []distribution.Descriptor `json:"manifests"`
// Annotations is an optional field that contains arbitrary metadata for the
// image index
Annotations map[string]string `json:"annotations,omitempty"`
}
// References returns the distribution descriptors for the referenced image
// manifests.
func (ii ImageIndex) References() []distribution.Descriptor {
return ii.Manifests
}
// DeserializedImageIndex wraps ManifestList with a copy of the original
// JSON.
type DeserializedImageIndex struct {
ImageIndex
// canonical is the canonical byte representation of the Manifest.
canonical []byte
}
// FromDescriptors takes a slice of descriptors and a map of annotations, and
// returns a DeserializedManifestList which contains the resulting manifest list
// and its JSON representation. If annotations is nil or empty then the
// annotations property will be omitted from the JSON representation.
func FromDescriptors(descriptors []distribution.Descriptor, annotations map[string]string) (*DeserializedImageIndex, error) {
return fromDescriptorsWithMediaType(descriptors, annotations, v1.MediaTypeImageIndex)
}
// fromDescriptorsWithMediaType is for testing purposes, it's useful to be able to specify the media type explicitly
func fromDescriptorsWithMediaType(descriptors []distribution.Descriptor, annotations map[string]string, mediaType string) (_ *DeserializedImageIndex, err error) {
m := ImageIndex{
Versioned: manifest.Versioned{
SchemaVersion: IndexSchemaVersion.SchemaVersion,
MediaType: mediaType,
},
Annotations: annotations,
}
m.Manifests = make([]distribution.Descriptor, len(descriptors))
copy(m.Manifests, descriptors)
deserialized := DeserializedImageIndex{
ImageIndex: m,
}
deserialized.canonical, err = json.MarshalIndent(&m, "", " ")
return &deserialized, err
}
// UnmarshalJSON populates a new ManifestList struct from JSON data.
func (m *DeserializedImageIndex) 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 ImageIndex
if err := json.Unmarshal(m.canonical, &manifestList); err != nil {
return err
}
m.ImageIndex = manifestList
return nil
}
// MarshalJSON returns the contents of canonical. If canonical is empty,
// marshals the inner contents.
func (m *DeserializedImageIndex) MarshalJSON() ([]byte, error) {
if len(m.canonical) > 0 {
return m.canonical, nil
}
return nil, errors.New("JSON representation not initialized in DeserializedImageIndex")
}
// Payload returns the raw content of the manifest list. The contents can be
// used to calculate the content identifier.
func (m DeserializedImageIndex) Payload() (string, []byte, error) {
mediaType := m.MediaType
if m.MediaType == "" {
mediaType = v1.MediaTypeImageIndex
}
return mediaType, m.canonical, nil
}
// 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 struct {
Config interface{} `json:"config,omitempty"`
Layers interface{} `json:"layers,omitempty"`
}
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
}