distribution/manifest/manifestlist/manifestlist.go

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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
}