package ocischema import ( "encoding/json" "errors" "fmt" "github.com/docker/distribution" "github.com/docker/distribution/manifest" "github.com/opencontainers/go-digest" "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) { 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), 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 }