open-nomad/vendor/github.com/docker/distribution/manifests.go

126 lines
4.2 KiB
Go

package distribution
import (
"context"
"fmt"
"mime"
"github.com/opencontainers/go-digest"
)
// Manifest represents a registry object specifying a set of
// references and an optional target
type Manifest interface {
// References returns a list of objects which make up this manifest.
// A reference is anything which can be represented by a
// distribution.Descriptor. These can consist of layers, resources or other
// manifests.
//
// While no particular order is required, implementations should return
// them from highest to lowest priority. For example, one might want to
// return the base layer before the top layer.
References() []Descriptor
// Payload provides the serialized format of the manifest, in addition to
// the media type.
Payload() (mediaType string, payload []byte, err error)
}
// ManifestBuilder creates a manifest allowing one to include dependencies.
// Instances can be obtained from a version-specific manifest package. Manifest
// specific data is passed into the function which creates the builder.
type ManifestBuilder interface {
// Build creates the manifest from his builder.
Build(ctx context.Context) (Manifest, error)
// References returns a list of objects which have been added to this
// builder. The dependencies are returned in the order they were added,
// which should be from base to head.
References() []Descriptor
// AppendReference includes the given object in the manifest after any
// existing dependencies. If the add fails, such as when adding an
// unsupported dependency, an error may be returned.
//
// The destination of the reference is dependent on the manifest type and
// the dependency type.
AppendReference(dependency Describable) error
}
// ManifestService describes operations on image manifests.
type ManifestService interface {
// Exists returns true if the manifest exists.
Exists(ctx context.Context, dgst digest.Digest) (bool, error)
// Get retrieves the manifest specified by the given digest
Get(ctx context.Context, dgst digest.Digest, options ...ManifestServiceOption) (Manifest, error)
// Put creates or updates the given manifest returning the manifest digest
Put(ctx context.Context, manifest Manifest, options ...ManifestServiceOption) (digest.Digest, error)
// Delete removes the manifest specified by the given digest. Deleting
// a manifest that doesn't exist will return ErrManifestNotFound
Delete(ctx context.Context, dgst digest.Digest) error
}
// ManifestEnumerator enables iterating over manifests
type ManifestEnumerator interface {
// Enumerate calls ingester for each manifest.
Enumerate(ctx context.Context, ingester func(digest.Digest) error) error
}
// Describable is an interface for descriptors
type Describable interface {
Descriptor() Descriptor
}
// ManifestMediaTypes returns the supported media types for manifests.
func ManifestMediaTypes() (mediaTypes []string) {
for t := range mappings {
if t != "" {
mediaTypes = append(mediaTypes, t)
}
}
return
}
// UnmarshalFunc implements manifest unmarshalling a given MediaType
type UnmarshalFunc func([]byte) (Manifest, Descriptor, error)
var mappings = make(map[string]UnmarshalFunc, 0)
// UnmarshalManifest looks up manifest unmarshal functions based on
// MediaType
func UnmarshalManifest(ctHeader string, p []byte) (Manifest, Descriptor, error) {
// Need to look up by the actual media type, not the raw contents of
// the header. Strip semicolons and anything following them.
var mediaType string
if ctHeader != "" {
var err error
mediaType, _, err = mime.ParseMediaType(ctHeader)
if err != nil {
return nil, Descriptor{}, err
}
}
unmarshalFunc, ok := mappings[mediaType]
if !ok {
unmarshalFunc, ok = mappings[""]
if !ok {
return nil, Descriptor{}, fmt.Errorf("unsupported manifest media type and no default available: %s", mediaType)
}
}
return unmarshalFunc(p)
}
// RegisterManifestSchema registers an UnmarshalFunc for a given schema type. This
// should be called from specific
func RegisterManifestSchema(mediaType string, u UnmarshalFunc) error {
if _, ok := mappings[mediaType]; ok {
return fmt.Errorf("manifest media type registration would overwrite existing: %s", mediaType)
}
mappings[mediaType] = u
return nil
}