distribution/manifest/ocischema/builder.go

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package ocischema
import (
"context"
"errors"
"github.com/docker/distribution"
"github.com/docker/distribution/manifest"
"github.com/opencontainers/go-digest"
v1 "github.com/opencontainers/image-spec/specs-go/v1"
)
// Builder is a type for constructing manifests.
type Builder struct {
// bs is a BlobService used to publish the configuration blob.
bs distribution.BlobService
// configJSON references
configJSON []byte
// layers is a list of layer descriptors that gets built by successive
// calls to AppendReference.
layers []distribution.Descriptor
// Annotations contains arbitrary metadata relating to the targeted content.
annotations map[string]string
// For testing purposes
mediaType string
}
// NewManifestBuilder is used to build new manifests for the current schema
// version. It takes a BlobService so it can publish the configuration blob
// as part of the Build process, and annotations.
func NewManifestBuilder(bs distribution.BlobService, configJSON []byte, annotations map[string]string) distribution.ManifestBuilder {
mb := &Builder{
bs: bs,
configJSON: make([]byte, len(configJSON)),
annotations: annotations,
mediaType: v1.MediaTypeImageManifest,
}
copy(mb.configJSON, configJSON)
return mb
}
// SetMediaType assigns the passed mediatype or error if the mediatype is not a
// valid media type for oci image manifests currently: "" or "application/vnd.oci.image.manifest.v1+json"
func (mb *Builder) SetMediaType(mediaType string) error {
if mediaType != "" && mediaType != v1.MediaTypeImageManifest {
return errors.New("Invalid media type for OCI image manifest")
}
mb.mediaType = mediaType
return nil
}
// Build produces a final manifest from the given references.
func (mb *Builder) Build(ctx context.Context) (distribution.Manifest, error) {
m := Manifest{
Versioned: manifest.Versioned{
SchemaVersion: 2,
MediaType: mb.mediaType,
},
Layers: make([]distribution.Descriptor, len(mb.layers)),
Annotations: mb.annotations,
}
copy(m.Layers, mb.layers)
configDigest := digest.FromBytes(mb.configJSON)
var err error
m.Config, err = mb.bs.Stat(ctx, configDigest)
switch err {
case nil:
// Override MediaType, since Put always replaces the specified media
// type with application/octet-stream in the descriptor it returns.
m.Config.MediaType = v1.MediaTypeImageConfig
return FromStruct(m)
case distribution.ErrBlobUnknown:
// nop
default:
return nil, err
}
// Add config to the blob store
m.Config, err = mb.bs.Put(ctx, v1.MediaTypeImageConfig, mb.configJSON)
// Override MediaType, since Put always replaces the specified media
// type with application/octet-stream in the descriptor it returns.
m.Config.MediaType = v1.MediaTypeImageConfig
if err != nil {
return nil, err
}
return FromStruct(m)
}
// AppendReference adds a reference to the current ManifestBuilder.
func (mb *Builder) AppendReference(d distribution.Describable) error {
mb.layers = append(mb.layers, d.Descriptor())
return nil
}
// References returns the current references added to this builder.
func (mb *Builder) References() []distribution.Descriptor {
return mb.layers
}