blob: c0e9261be9321d0def57da5ca184c14707242a74 [file] [log] [blame]
package distribution
import (
var (
// ErrBlobExists returned when blob already exists
ErrBlobExists = errors.New("blob exists")
// ErrBlobDigestUnsupported when blob digest is an unsupported version.
ErrBlobDigestUnsupported = errors.New("unsupported blob digest")
// ErrBlobUnknown when blob is not found.
ErrBlobUnknown = errors.New("unknown blob")
// ErrBlobUploadUnknown returned when upload is not found.
ErrBlobUploadUnknown = errors.New("blob upload unknown")
// ErrBlobInvalidLength returned when the blob has an expected length on
// commit, meaning mismatched with the descriptor or an invalid value.
ErrBlobInvalidLength = errors.New("blob invalid length")
// ErrBlobInvalidDigest returned when digest check fails.
type ErrBlobInvalidDigest struct {
Digest digest.Digest
Reason error
func (err ErrBlobInvalidDigest) Error() string {
return fmt.Sprintf("invalid digest for referenced layer: %v, %v",
err.Digest, err.Reason)
// ErrBlobMounted returned when a blob is mounted from another repository
// instead of initiating an upload session.
type ErrBlobMounted struct {
From reference.Canonical
Descriptor Descriptor
func (err ErrBlobMounted) Error() string {
return fmt.Sprintf("blob mounted from: %v to: %v",
err.From, err.Descriptor)
// Descriptor describes targeted content. Used in conjunction with a blob
// store, a descriptor can be used to fetch, store and target any kind of
// blob. The struct also describes the wire protocol format. Fields should
// only be added but never changed.
type Descriptor struct {
// MediaType describe the type of the content. All text based formats are
// encoded as utf-8.
MediaType string `json:"mediaType,omitempty"`
// Size in bytes of content.
Size int64 `json:"size,omitempty"`
// Digest uniquely identifies the content. A byte stream can be verified
// against this digest.
Digest digest.Digest `json:"digest,omitempty"`
// URLs contains the source URLs of this content.
URLs []string `json:"urls,omitempty"`
// Annotations contains arbitrary metadata relating to the targeted content.
Annotations map[string]string `json:"annotations,omitempty"`
// Platform describes the platform which the image in the manifest runs on.
// This should only be used when referring to a manifest.
Platform *v1.Platform `json:"platform,omitempty"`
// NOTE: Before adding a field here, please ensure that all
// other options have been exhausted. Much of the type relationships
// depend on the simplicity of this type.
// Descriptor returns the descriptor, to make it satisfy the Describable
// interface. Note that implementations of Describable are generally objects
// which can be described, not simply descriptors; this exception is in place
// to make it more convenient to pass actual descriptors to functions that
// expect Describable objects.
func (d Descriptor) Descriptor() Descriptor {
return d
// BlobStatter makes blob descriptors available by digest. The service may
// provide a descriptor of a different digest if the provided digest is not
// canonical.
type BlobStatter interface {
// Stat provides metadata about a blob identified by the digest. If the
// blob is unknown to the describer, ErrBlobUnknown will be returned.
Stat(ctx context.Context, dgst digest.Digest) (Descriptor, error)
// BlobDeleter enables deleting blobs from storage.
type BlobDeleter interface {
Delete(ctx context.Context, dgst digest.Digest) error
// BlobEnumerator enables iterating over blobs from storage
type BlobEnumerator interface {
Enumerate(ctx context.Context, ingester func(dgst digest.Digest) error) error
// BlobDescriptorService manages metadata about a blob by digest. Most
// implementations will not expose such an interface explicitly. Such mappings
// should be maintained by interacting with the BlobIngester. Hence, this is
// left off of BlobService and BlobStore.
type BlobDescriptorService interface {
// SetDescriptor assigns the descriptor to the digest. The provided digest and
// the digest in the descriptor must map to identical content but they may
// differ on their algorithm. The descriptor must have the canonical
// digest of the content and the digest algorithm must match the
// annotators canonical algorithm.
// Such a facility can be used to map blobs between digest domains, with
// the restriction that the algorithm of the descriptor must match the
// canonical algorithm (ie sha256) of the annotator.
SetDescriptor(ctx context.Context, dgst digest.Digest, desc Descriptor) error
// Clear enables descriptors to be unlinked
Clear(ctx context.Context, dgst digest.Digest) error
// BlobDescriptorServiceFactory creates middleware for BlobDescriptorService.
type BlobDescriptorServiceFactory interface {
BlobAccessController(svc BlobDescriptorService) BlobDescriptorService
// ReadSeekCloser is the primary reader type for blob data, combining
// io.ReadSeeker with io.Closer.
type ReadSeekCloser interface {
// BlobProvider describes operations for getting blob data.
type BlobProvider interface {
// Get returns the entire blob identified by digest along with the descriptor.
Get(ctx context.Context, dgst digest.Digest) ([]byte, error)
// Open provides a ReadSeekCloser to the blob identified by the provided
// descriptor. If the blob is not known to the service, an error will be
// returned.
Open(ctx context.Context, dgst digest.Digest) (ReadSeekCloser, error)
// BlobServer can serve blobs via http.
type BlobServer interface {
// ServeBlob attempts to serve the blob, identified by dgst, via http. The
// service may decide to redirect the client elsewhere or serve the data
// directly.
// This handler only issues successful responses, such as 2xx or 3xx,
// meaning it serves data or issues a redirect. If the blob is not
// available, an error will be returned and the caller may still issue a
// response.
// The implementation may serve the same blob from a different digest
// domain. The appropriate headers will be set for the blob, unless they
// have already been set by the caller.
ServeBlob(ctx context.Context, w http.ResponseWriter, r *http.Request, dgst digest.Digest) error
// BlobIngester ingests blob data.
type BlobIngester interface {
// Put inserts the content p into the blob service, returning a descriptor
// or an error.
Put(ctx context.Context, mediaType string, p []byte) (Descriptor, error)
// Create allocates a new blob writer to add a blob to this service. The
// returned handle can be written to and later resumed using an opaque
// identifier. With this approach, one can Close and Resume a BlobWriter
// multiple times until the BlobWriter is committed or cancelled.
Create(ctx context.Context, options ...BlobCreateOption) (BlobWriter, error)
// Resume attempts to resume a write to a blob, identified by an id.
Resume(ctx context.Context, id string) (BlobWriter, error)
// BlobCreateOption is a general extensible function argument for blob creation
// methods. A BlobIngester may choose to honor any or none of the given
// BlobCreateOptions, which can be specific to the implementation of the
// BlobIngester receiving them.
// TODO (brianbland): unify this with ManifestServiceOption in the future
type BlobCreateOption interface {
Apply(interface{}) error
// CreateOptions is a collection of blob creation modifiers relevant to general
// blob storage intended to be configured by the BlobCreateOption.Apply method.
type CreateOptions struct {
Mount struct {
ShouldMount bool
From reference.Canonical
// Stat allows to pass precalculated descriptor to link and return.
// Blob access check will be skipped if set.
Stat *Descriptor
// BlobWriter provides a handle for inserting data into a blob store.
// Instances should be obtained from BlobWriteService.Writer and
// BlobWriteService.Resume. If supported by the store, a writer can be
// recovered with the id.
type BlobWriter interface {
// Size returns the number of bytes written to this blob.
Size() int64
// ID returns the identifier for this writer. The ID can be used with the
// Blob service to later resume the write.
ID() string
// StartedAt returns the time this blob write was started.
StartedAt() time.Time
// Commit completes the blob writer process. The content is verified
// against the provided provisional descriptor, which may result in an
// error. Depending on the implementation, written data may be validated
// against the provisional descriptor fields. If MediaType is not present,
// the implementation may reject the commit or assign "application/octet-
// stream" to the blob. The returned descriptor may have a different
// digest depending on the blob store, referred to as the canonical
// descriptor.
Commit(ctx context.Context, provisional Descriptor) (canonical Descriptor, err error)
// Cancel ends the blob write without storing any data and frees any
// associated resources. Any data written thus far will be lost. Cancel
// implementations should allow multiple calls even after a commit that
// result in a no-op. This allows use of Cancel in a defer statement,
// increasing the assurance that it is correctly called.
Cancel(ctx context.Context) error
// BlobService combines the operations to access, read and write blobs. This
// can be used to describe remote blob services.
type BlobService interface {
// BlobStore represent the entire suite of blob related operations. Such an
// implementation can access, read, write, delete and serve blobs.
type BlobStore interface {