124 lines
3.7 KiB
Go
124 lines
3.7 KiB
Go
package ocischema
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import (
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"encoding/json"
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"errors"
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"fmt"
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"github.com/docker/distribution"
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"github.com/docker/distribution/manifest"
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"github.com/opencontainers/go-digest"
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"github.com/opencontainers/image-spec/specs-go/v1"
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)
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var (
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// SchemaVersion provides a pre-initialized version structure for this
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// packages version of the manifest.
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SchemaVersion = manifest.Versioned{
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SchemaVersion: 2, // historical value here.. does not pertain to OCI or docker version
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MediaType: v1.MediaTypeImageManifest,
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}
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)
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func init() {
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ocischemaFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
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m := new(DeserializedManifest)
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err := m.UnmarshalJSON(b)
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if err != nil {
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return nil, distribution.Descriptor{}, err
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}
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dgst := digest.FromBytes(b)
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return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: v1.MediaTypeImageManifest}, err
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}
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err := distribution.RegisterManifestSchema(v1.MediaTypeImageManifest, ocischemaFunc)
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if err != nil {
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panic(fmt.Sprintf("Unable to register manifest: %s", err))
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}
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}
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// Manifest defines a ocischema manifest.
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type Manifest struct {
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manifest.Versioned
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// Config references the image configuration as a blob.
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Config distribution.Descriptor `json:"config"`
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// Layers lists descriptors for the layers referenced by the
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// configuration.
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Layers []distribution.Descriptor `json:"layers"`
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// Annotations contains arbitrary metadata for the image manifest.
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Annotations map[string]string `json:"annotations,omitempty"`
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}
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// References returns the descriptors of this manifests references.
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func (m Manifest) References() []distribution.Descriptor {
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references := make([]distribution.Descriptor, 0, 1+len(m.Layers))
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references = append(references, m.Config)
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references = append(references, m.Layers...)
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return references
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}
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// Target returns the target of this manifest.
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func (m Manifest) Target() distribution.Descriptor {
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return m.Config
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}
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// DeserializedManifest wraps Manifest with a copy of the original JSON.
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// It satisfies the distribution.Manifest interface.
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type DeserializedManifest struct {
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Manifest
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// canonical is the canonical byte representation of the Manifest.
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canonical []byte
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}
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// FromStruct takes a Manifest structure, marshals it to JSON, and returns a
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// DeserializedManifest which contains the manifest and its JSON representation.
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func FromStruct(m Manifest) (*DeserializedManifest, error) {
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var deserialized DeserializedManifest
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deserialized.Manifest = m
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var err error
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deserialized.canonical, err = json.MarshalIndent(&m, "", " ")
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return &deserialized, err
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}
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// UnmarshalJSON populates a new Manifest struct from JSON data.
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func (m *DeserializedManifest) UnmarshalJSON(b []byte) error {
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m.canonical = make([]byte, len(b), len(b))
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// store manifest in canonical
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copy(m.canonical, b)
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// Unmarshal canonical JSON into Manifest object
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var manifest Manifest
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if err := json.Unmarshal(m.canonical, &manifest); err != nil {
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return err
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}
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if manifest.MediaType != "" && manifest.MediaType != v1.MediaTypeImageManifest {
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return fmt.Errorf("if present, mediaType in manifest should be '%s' not '%s'",
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v1.MediaTypeImageManifest, manifest.MediaType)
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}
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m.Manifest = manifest
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return nil
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}
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// MarshalJSON returns the contents of canonical. If canonical is empty,
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// marshals the inner contents.
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func (m *DeserializedManifest) MarshalJSON() ([]byte, error) {
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if len(m.canonical) > 0 {
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return m.canonical, nil
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}
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return nil, errors.New("JSON representation not initialized in DeserializedManifest")
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}
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// Payload returns the raw content of the manifest. The contents can be used to
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// calculate the content identifier.
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func (m DeserializedManifest) Payload() (string, []byte, error) {
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return v1.MediaTypeImageManifest, m.canonical, nil
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}
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