distribution/layer.go
Stephen J Day 27b03f2136 Move layer interface definitions to distribution package
After consideration, it has been decided that the interfaces defined in the
storage package provide a good base for interacting with various registry
instances. Whether interacting with a remote API or a local, on-disk registry,
these types have proved flexible. By moving them here, they can become the
central components of interacting with distribution components.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-02-12 14:26:46 -08:00

90 lines
2.5 KiB
Go

package distribution
import (
"fmt"
"io"
"time"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/manifest"
)
// Layer provides a readable and seekable layer object. Typically,
// implementations are *not* goroutine safe.
type Layer interface {
// http.ServeContent requires an efficient implementation of
// ReadSeeker.Seek(0, os.SEEK_END).
io.ReadSeeker
io.Closer
// Name returns the repository under which this layer is linked.
Name() string // TODO(stevvooe): struggling with nomenclature: should this be "repo" or "name"?
// Digest returns the unique digest of the blob, which is the tarsum for
// layers.
Digest() digest.Digest
// CreatedAt returns the time this layer was created.
CreatedAt() time.Time
}
// LayerUpload provides a handle for working with in-progress uploads.
// Instances can be obtained from the LayerService.Upload and
// LayerService.Resume.
type LayerUpload interface {
io.WriteSeeker
io.ReaderFrom
io.Closer
// Name of the repository under which the layer will be linked.
Name() string
// UUID returns the identifier for this upload.
UUID() string
// StartedAt returns the time this layer upload was started.
StartedAt() time.Time
// Finish marks the upload as completed, returning a valid handle to the
// uploaded layer. The digest is validated against the contents of the
// uploaded layer.
Finish(digest digest.Digest) (Layer, error)
// Cancel the layer upload process.
Cancel() error
}
var (
// ErrLayerExists returned when layer already exists
ErrLayerExists = fmt.Errorf("layer exists")
// ErrLayerTarSumVersionUnsupported when tarsum is unsupported version.
ErrLayerTarSumVersionUnsupported = fmt.Errorf("unsupported tarsum version")
// ErrLayerUploadUnknown returned when upload is not found.
ErrLayerUploadUnknown = fmt.Errorf("layer upload unknown")
// ErrLayerClosed returned when an operation is attempted on a closed
// Layer or LayerUpload.
ErrLayerClosed = fmt.Errorf("layer closed")
)
// ErrUnknownLayer returned when layer cannot be found.
type ErrUnknownLayer struct {
FSLayer manifest.FSLayer
}
func (err ErrUnknownLayer) Error() string {
return fmt.Sprintf("unknown layer %v", err.FSLayer.BlobSum)
}
// ErrLayerInvalidDigest returned when tarsum check fails.
type ErrLayerInvalidDigest struct {
Digest digest.Digest
Reason error
}
func (err ErrLayerInvalidDigest) Error() string {
return fmt.Sprintf("invalid digest for referenced layer: %v, %v",
err.Digest, err.Reason)
}