distribution/manifest/schema2/builder.go
Stephen J Day 9c88801a12
context: remove definition of Context
Back in the before time, the best practices surrounding usage of Context
weren't quite worked out. We defined our own type to make usage easier.
As this packaged was used elsewhere, it make it more and more
challenging to integrate with the forked `Context` type. Now that it is
available in the standard library, we can just use that one directly.

To make usage more consistent, we now use `dcontext` when referring to
the distribution context package.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2017-08-11 15:53:31 -07:00

85 lines
2.5 KiB
Go

package schema2
import (
"context"
"github.com/docker/distribution"
"github.com/opencontainers/go-digest"
)
// builder is a type for constructing manifests.
type builder struct {
// bs is a BlobService used to publish the configuration blob.
bs distribution.BlobService
// configMediaType is media type used to describe configuration
configMediaType string
// configJSON references
configJSON []byte
// dependencies is a list of descriptors that gets built by successive
// calls to AppendReference. In case of image configuration these are layers.
dependencies []distribution.Descriptor
}
// 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.
func NewManifestBuilder(bs distribution.BlobService, configMediaType string, configJSON []byte) distribution.ManifestBuilder {
mb := &builder{
bs: bs,
configMediaType: configMediaType,
configJSON: make([]byte, len(configJSON)),
}
copy(mb.configJSON, configJSON)
return mb
}
// Build produces a final manifest from the given references.
func (mb *builder) Build(ctx context.Context) (distribution.Manifest, error) {
m := Manifest{
Versioned: SchemaVersion,
Layers: make([]distribution.Descriptor, len(mb.dependencies)),
}
copy(m.Layers, mb.dependencies)
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 = mb.configMediaType
return FromStruct(m)
case distribution.ErrBlobUnknown:
// nop
default:
return nil, err
}
// Add config to the blob store
m.Config, err = mb.bs.Put(ctx, mb.configMediaType, mb.configJSON)
// Override MediaType, since Put always replaces the specified media
// type with application/octet-stream in the descriptor it returns.
m.Config.MediaType = mb.configMediaType
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.dependencies = append(mb.dependencies, d.Descriptor())
return nil
}
// References returns the current references added to this builder.
func (mb *builder) References() []distribution.Descriptor {
return mb.dependencies
}