forked from linuxkit/linuxkit
/
source.go
92 lines (80 loc) · 2.31 KB
/
source.go
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package docker
import (
"encoding/json"
"fmt"
"io"
"github.com/containerd/containerd/reference"
v1 "github.com/google/go-containerregistry/pkg/v1"
imagespec "github.com/opencontainers/image-spec/specs-go/v1"
)
type readCloser struct {
r io.ReadCloser
closer func() error
}
func (t readCloser) Read(p []byte) (int, error) {
return t.r.Read(p)
}
func (t readCloser) Close() error {
return t.closer()
}
// ImageSource a source for an image in the docker engine.
// Implements a moby.ImageSource.
type ImageSource struct {
ref *reference.Spec
}
// NewSource return an ImageSource for a specific ref from docker.
func NewSource(ref *reference.Spec) ImageSource {
return ImageSource{
ref: ref,
}
}
// Config return the imagespec.ImageConfig for the given source.
func (d ImageSource) Config() (imagespec.ImageConfig, error) {
cli, err := Client()
if err != nil {
return imagespec.ImageConfig{}, err
}
inspect, err := InspectImage(cli, d.ref)
if err != nil {
return imagespec.ImageConfig{}, err
}
// because the other parts expect OCI go-spec structs, not dockertypes structs,
// the easiest way to do this is to convert via json
configJSON, err := json.Marshal(inspect)
if err != nil {
return imagespec.ImageConfig{}, fmt.Errorf("unable to convert image config to json: %v", err)
}
var ociConfig imagespec.Image
err = json.Unmarshal(configJSON, &ociConfig)
return ociConfig.Config, err
}
// TarReader return an io.ReadCloser to read the filesystem contents of the image.
func (d ImageSource) TarReader() (io.ReadCloser, error) {
container, err := Create(d.ref.String(), false)
if err != nil {
return nil, fmt.Errorf("Failed to create docker image %s: %v", d.ref, err)
}
contents, err := Export(container)
if err != nil {
return nil, fmt.Errorf("Failed to docker export container from container %s: %v", container, err)
}
return readCloser{
r: contents,
closer: func() error {
contents.Close()
return Rm(container)
},
}, nil
}
// V1TarReader return an io.ReadCloser to read the save of the image
func (d ImageSource) V1TarReader(overrideName string) (io.ReadCloser, error) {
saveName := d.ref.String()
if overrideName != "" {
saveName = overrideName
}
return Save(saveName)
}
// Descriptor return the descriptor of the image.
func (d ImageSource) Descriptor() *v1.Descriptor {
return nil
}