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" ) // SchemaVersion provides a pre-initialized version structure for OCI Image // Manifests var SchemaVersion = manifest.Versioned{ SchemaVersion: 2, 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{ MediaType: v1.MediaTypeImageManifest, Digest: dgst, Size: int64(len(b)), Annotations: m.Annotations, }, 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 mfst Manifest if err := json.Unmarshal(m.canonical, &mfst); err != nil { return err } if mfst.MediaType != "" && mfst.MediaType != v1.MediaTypeImageManifest { return fmt.Errorf("if present, mediaType in manifest should be '%s' not '%s'", v1.MediaTypeImageManifest, mfst.MediaType) } m.Manifest = mfst 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 } // 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 struct { Manifests interface{} `json:"manifests,omitempty"` } 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 }