distribution/manifest/schema2/manifest.go

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package schema2
import (
"encoding/json"
"errors"
"fmt"
"github.com/docker/distribution"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/manifest"
)
const (
// MediaTypeManifest specifies the mediaType for the current version.
MediaTypeManifest = "application/vnd.docker.distribution.manifest.v2+json"
// MediaTypeConfig specifies the mediaType for the image configuration.
MediaTypeConfig = "application/vnd.docker.container.image.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"
)
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 returnes the descriptors of this manifests references.
func (m Manifest) References() []distribution.Descriptor {
return m.Layers
}
// Target returns the target of this signed 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), 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
}
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
}