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// Copyright 2018 Google LLC All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package daemon
import (
"bytes"
"context"
"io"
"sync"
"github.com/google/go-containerregistry/pkg/name"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/tarball"
"github.com/google/go-containerregistry/pkg/v1/types"
)
type image struct {
ref name.Reference
opener *imageOpener
tarballImage v1.Image
id *v1.Hash
once sync.Once
err error
}
type imageOpener struct {
ref name.Reference
ctx context.Context
buffered bool
client Client
once sync.Once
bytes []byte
err error
}
func (i *imageOpener) saveImage() (io.ReadCloser, error) {
return i.client.ImageSave(i.ctx, []string{i.ref.Name()})
}
func (i *imageOpener) bufferedOpener() (io.ReadCloser, error) {
// Store the tarball in memory and return a new reader into the bytes each time we need to access something.
i.once.Do(func() {
i.bytes, i.err = func() ([]byte, error) {
rc, err := i.saveImage()
if err != nil {
return nil, err
}
defer rc.Close()
return io.ReadAll(rc)
}()
})
// Wrap the bytes in a ReadCloser so it looks like an opened file.
return io.NopCloser(bytes.NewReader(i.bytes)), i.err
}
func (i *imageOpener) opener() tarball.Opener {
if i.buffered {
return i.bufferedOpener
}
// To avoid storing the tarball in memory, do a save every time we need to access something.
return i.saveImage
}
// Image provides access to an image reference from the Docker daemon,
// applying functional options to the underlying imageOpener before
// resolving the reference into a v1.Image.
func Image(ref name.Reference, options ...Option) (v1.Image, error) {
o, err := makeOptions(options...)
if err != nil {
return nil, err
}
i := &imageOpener{
ref: ref,
buffered: o.buffered,
client: o.client,
ctx: o.ctx,
}
img := &image{
ref: ref,
opener: i,
}
// Eagerly fetch Image ID to ensure it actually exists.
// https://github.com/google/go-containerregistry/issues/1186
id, err := img.ConfigName()
if err != nil {
return nil, err
}
img.id = &id
return img, nil
}
func (i *image) initialize() error {
// Don't re-initialize tarball if already initialized.
if i.tarballImage == nil {
i.once.Do(func() {
i.tarballImage, i.err = tarball.Image(i.opener.opener(), nil)
})
}
return i.err
}
func (i *image) Layers() ([]v1.Layer, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.Layers()
}
func (i *image) MediaType() (types.MediaType, error) {
if err := i.initialize(); err != nil {
return "", err
}
return i.tarballImage.MediaType()
}
func (i *image) Size() (int64, error) {
if err := i.initialize(); err != nil {
return 0, err
}
return i.tarballImage.Size()
}
func (i *image) ConfigName() (v1.Hash, error) {
if i.id != nil {
return *i.id, nil
}
res, _, err := i.opener.client.ImageInspectWithRaw(i.opener.ctx, i.ref.String())
if err != nil {
return v1.Hash{}, err
}
return v1.NewHash(res.ID)
}
func (i *image) ConfigFile() (*v1.ConfigFile, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.ConfigFile()
}
func (i *image) RawConfigFile() ([]byte, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.RawConfigFile()
}
func (i *image) Digest() (v1.Hash, error) {
if err := i.initialize(); err != nil {
return v1.Hash{}, err
}
return i.tarballImage.Digest()
}
func (i *image) Manifest() (*v1.Manifest, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.Manifest()
}
func (i *image) RawManifest() ([]byte, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.RawManifest()
}
func (i *image) LayerByDigest(h v1.Hash) (v1.Layer, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.LayerByDigest(h)
}
func (i *image) LayerByDiffID(h v1.Hash) (v1.Layer, error) {
if err := i.initialize(); err != nil {
return nil, err
}
return i.tarballImage.LayerByDiffID(h)
}
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