Golang registry.Session类代码示例

func (s *TagStore) pullV2Repository(eng *engine.Engine, r *registry.Session, out io.Writer, localName, remoteName, tag string, sf *utils.StreamFormatter, parallel bool) error {
	var layersDownloaded bool
	if tag == "" {
		log.Debugf("Pulling tag list from V2 registry for %s", remoteName)
		tags, err := r.GetV2RemoteTags(remoteName, nil)
		if err != nil {
			return err
		}
		for _, t := range tags {
			if downloaded, err := s.pullV2Tag(eng, r, out, localName, remoteName, t, sf, parallel); err != nil {
				return err
			} else if downloaded {
				layersDownloaded = true
			}
		}
	} else {
		if downloaded, err := s.pullV2Tag(eng, r, out, localName, remoteName, tag, sf, parallel); err != nil {
			return err
		} else if downloaded {
			layersDownloaded = true
		}
	}

	requestedTag := localName
	if len(tag) > 0 {
		requestedTag = localName + ":" + tag
	}
	WriteStatus(requestedTag, out, sf, layersDownloaded)
	return nil
}

// PushV2Image pushes the image content to the v2 registry, first buffering the contents to disk
func (s *TagStore) pushV2Image(r *registry.Session, img *image.Image, endpoint *registry.Endpoint, imageName, sumType, sumStr string, sf *utils.StreamFormatter, out io.Writer, auth *registry.RequestAuthorization) error {
	out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Buffering to Disk", nil))

	image, err := s.graph.Get(img.ID)
	if err != nil {
		return err
	}
	arch, err := image.TarLayer()
	if err != nil {
		return err
	}
	tf, err := s.graph.newTempFile()
	if err != nil {
		return err
	}
	defer func() {
		tf.Close()
		os.Remove(tf.Name())
	}()

	size, err := bufferToFile(tf, arch)
	if err != nil {
		return err
	}

	// Send the layer
	log.Debugf("rendered layer for %s of [%d] size", img.ID, size)

	if err := r.PutV2ImageBlob(endpoint, imageName, sumType, sumStr, utils.ProgressReader(tf, int(size), out, sf, false, utils.TruncateID(img.ID), "Pushing"), auth); err != nil {
		out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Image push failed", nil))
		return err
	}
	out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Image successfully pushed", nil))
	return nil
}

func (s *TagStore) pushImageToEndpoint(endpoint string, out io.Writer, remoteName string, imageIDs []string,
	tags map[string][]string, repo *registry.RepositoryData, sf *utils.StreamFormatter, r *registry.Session) error {
	workerCount := len(imageIDs)
	// start a maximum of 5 workers to check if images exist on the specified endpoint.
	if workerCount > 5 {
		workerCount = 5
	}
	var (
		wg           = &sync.WaitGroup{}
		imageData    = make(chan imagePushData, workerCount*2)
		imagesToPush = make(chan string, workerCount*2)
		pushes       = make(chan map[string]struct{}, 1)
	)
	for i := 0; i < workerCount; i++ {
		wg.Add(1)
		go lookupImageOnEndpoint(wg, r, out, sf, imageData, imagesToPush)
	}
	// start a go routine that consumes the images to push
	go func() {
		shouldPush := make(map[string]struct{})
		for id := range imagesToPush {
			shouldPush[id] = struct{}{}
		}
		pushes <- shouldPush
	}()
	for _, id := range imageIDs {
		imageData <- imagePushData{
			id:       id,
			endpoint: endpoint,
			tokens:   repo.Tokens,
		}
	}
	// close the channel to notify the workers that there will be no more images to check.
	close(imageData)
	wg.Wait()
	close(imagesToPush)
	// wait for all the images that require pushes to be collected into a consumable map.
	shouldPush := <-pushes
	// finish by pushing any images and tags to the endpoint.  The order that the images are pushed
	// is very important that is why we are still iterating over the ordered list of imageIDs.
	for _, id := range imageIDs {
		if _, push := shouldPush[id]; push {
			if _, err := s.pushImage(r, out, id, endpoint, repo.Tokens, sf); err != nil {
				// FIXME: Continue on error?
				return err
			}
		}
		for _, tag := range tags[id] {
			out.Write(sf.FormatStatus("", "Pushing tag for rev [%s] on {%s}", common.TruncateID(id), endpoint+"repositories/"+remoteName+"/tags/"+tag))
			if err := r.PushRegistryTag(remoteName, id, tag, endpoint, repo.Tokens); err != nil {
				return err
			}
		}
	}
	return nil
}

// lookupImageOnEndpoint checks the specified endpoint to see if an image exists
// and if it is absent then it sends the image id to the channel to be pushed.
func lookupImageOnEndpoint(wg *sync.WaitGroup, r *registry.Session, out io.Writer, sf *utils.StreamFormatter,
	images chan imagePushData, imagesToPush chan string) {
	defer wg.Done()
	for image := range images {
		if err := r.LookupRemoteImage(image.id, image.endpoint, image.tokens); err != nil {
			log.Errorf("Error in LookupRemoteImage: %s", err)
			imagesToPush <- image.id
			continue
		}
		out.Write(sf.FormatStatus("", "Image %s already pushed, skipping", common.TruncateID(image.id)))
	}
}

// PushV2Image pushes the image content to the v2 registry, first buffering the contents to disk
func (s *TagStore) pushV2Image(r *registry.Session, img *image.Image, endpoint *registry.Endpoint, imageName string, sf *utils.StreamFormatter, out io.Writer, auth *registry.RequestAuthorization) (string, error) {
	out.Write(sf.FormatProgress(common.TruncateID(img.ID), "Buffering to Disk", nil))

	image, err := s.graph.Get(img.ID)
	if err != nil {
		return "", err
	}
	arch, err := image.TarLayer()
	if err != nil {
		return "", err
	}
	defer arch.Close()

	tf, err := s.graph.newTempFile()
	if err != nil {
		return "", err
	}
	defer func() {
		tf.Close()
		os.Remove(tf.Name())
	}()

	h := sha256.New()
	size, err := bufferToFile(tf, io.TeeReader(arch, h))
	if err != nil {
		return "", err
	}
	dgst := digest.NewDigest("sha256", h)

	// Send the layer
	log.Debugf("rendered layer for %s of [%d] size", img.ID, size)

	if err := r.PutV2ImageBlob(endpoint, imageName, dgst.Algorithm(), dgst.Hex(),
		progressreader.New(progressreader.Config{
			In:        tf,
			Out:       out,
			Formatter: sf,
			Size:      int(size),
			NewLines:  false,
			ID:        common.TruncateID(img.ID),
			Action:    "Pushing",
		}), auth); err != nil {
		out.Write(sf.FormatProgress(common.TruncateID(img.ID), "Image push failed", nil))
		return "", err
	}
	out.Write(sf.FormatProgress(common.TruncateID(img.ID), "Image successfully pushed", nil))
	return dgst.String(), nil
}

func (s *TagStore) pullV2Repository(eng *engine.Engine, r *registry.Session, out io.Writer, localName, remoteName, tag string, sf *utils.StreamFormatter, parallel bool) error {
	if tag == "" {
		log.Debugf("Pulling tag list from V2 registry for %s", remoteName)
		tags, err := r.GetV2RemoteTags(remoteName, nil)
		if err != nil {
			return err
		}
		for _, t := range tags {
			if err := s.pullV2Tag(eng, r, out, localName, remoteName, t, sf, parallel); err != nil {
				return err
			}
		}
	} else {
		if err := s.pullV2Tag(eng, r, out, localName, remoteName, tag, sf, parallel); err != nil {
			return err
		}
	}

	return nil
}

// pushRepository pushes layers that do not already exist on the registry.
func (s *TagStore) pushRepository(r *registry.Session, out io.Writer,
	repoInfo *registry.RepositoryInfo, localRepo map[string]string,
	tag string, sf *utils.StreamFormatter) error {
	log.Debugf("Local repo: %s", localRepo)
	out = utils.NewWriteFlusher(out)
	imgList, tags, err := s.getImageList(localRepo, tag)
	if err != nil {
		return err
	}
	out.Write(sf.FormatStatus("", "Sending image list"))

	imageIndex := s.createImageIndex(imgList, tags)
	log.Debugf("Preparing to push %s with the following images and tags", localRepo)
	for _, data := range imageIndex {
		log.Debugf("Pushing ID: %s with Tag: %s", data.ID, data.Tag)
	}
	// Register all the images in a repository with the registry
	// If an image is not in this list it will not be associated with the repository
	repoData, err := r.PushImageJSONIndex(repoInfo.RemoteName, imageIndex, false, nil)
	if err != nil {
		return err
	}
	nTag := 1
	if tag == "" {
		nTag = len(localRepo)
	}
	out.Write(sf.FormatStatus("", "Pushing repository %s (%d tags)", repoInfo.CanonicalName, nTag))
	// push the repository to each of the endpoints only if it does not exist.
	for _, endpoint := range repoData.Endpoints {
		if err := s.pushImageToEndpoint(endpoint, out, repoInfo.RemoteName, imgList, tags, repoData, sf, r); err != nil {
			return err
		}
	}
	_, err = r.PushImageJSONIndex(repoInfo.RemoteName, imageIndex, true, repoData.Endpoints)
	return err
}

func (s *TagStore) pushImage(r *registry.Session, out io.Writer, imgID, ep string, token []string, sf *utils.StreamFormatter) (checksum string, err error) {
	out = utils.NewWriteFlusher(out)
	jsonRaw, err := ioutil.ReadFile(path.Join(s.graph.Root, imgID, "json"))
	if err != nil {
		return "", fmt.Errorf("Cannot retrieve the path for {%s}: %s", imgID, err)
	}
	out.Write(sf.FormatProgress(common.TruncateID(imgID), "Pushing", nil))

	imgData := &registry.ImgData{
		ID: imgID,
	}

	// Send the json
	if err := r.PushImageJSONRegistry(imgData, jsonRaw, ep, token); err != nil {
		if err == registry.ErrAlreadyExists {
			out.Write(sf.FormatProgress(common.TruncateID(imgData.ID), "Image already pushed, skipping", nil))
			return "", nil
		}
		return "", err
	}

	layerData, err := s.graph.TempLayerArchive(imgID, sf, out)
	if err != nil {
		return "", fmt.Errorf("Failed to generate layer archive: %s", err)
	}
	defer os.RemoveAll(layerData.Name())

	// Send the layer
	log.Debugf("rendered layer for %s of [%d] size", imgData.ID, layerData.Size)

	checksum, checksumPayload, err := r.PushImageLayerRegistry(imgData.ID,
		progressreader.New(progressreader.Config{
			In:        layerData,
			Out:       out,
			Formatter: sf,
			Size:      int(layerData.Size),
			NewLines:  false,
			ID:        common.TruncateID(imgData.ID),
			Action:    "Pushing",
		}), ep, token, jsonRaw)
	if err != nil {
		return "", err
	}
	imgData.Checksum = checksum
	imgData.ChecksumPayload = checksumPayload
	// Send the checksum
	if err := r.PushImageChecksumRegistry(imgData, ep, token); err != nil {
		return "", err
	}

	out.Write(sf.FormatProgress(common.TruncateID(imgData.ID), "Image successfully pushed", nil))
	return imgData.Checksum, nil
}

func (s *TagStore) pullV2Repository(r *registry.Session, out io.Writer, repoInfo *registry.RepositoryInfo, tag string, sf *streamformatter.StreamFormatter) error {
	endpoint, err := r.V2RegistryEndpoint(repoInfo.Index)
	if err != nil {
		if repoInfo.Index.Official {
			logrus.Debugf("Unable to pull from V2 registry, falling back to v1: %s", err)
			return ErrV2RegistryUnavailable
		}
		return fmt.Errorf("error getting registry endpoint: %s", err)
	}
	auth, err := r.GetV2Authorization(endpoint, repoInfo.RemoteName, true)
	if err != nil {
		return fmt.Errorf("error getting authorization: %s", err)
	}
	if !auth.CanAuthorizeV2() {
		return ErrV2RegistryUnavailable
	}

	var layersDownloaded bool
	if tag == "" {
		logrus.Debugf("Pulling tag list from V2 registry for %s", repoInfo.CanonicalName)
		tags, err := r.GetV2RemoteTags(endpoint, repoInfo.RemoteName, auth)
		if err != nil {
			return err
		}
		if len(tags) == 0 {
			return registry.ErrDoesNotExist
		}
		for _, t := range tags {
			if downloaded, err := s.pullV2Tag(r, out, endpoint, repoInfo, t, sf, auth); err != nil {
				return err
			} else if downloaded {
				layersDownloaded = true
			}
		}
	} else {
		if downloaded, err := s.pullV2Tag(r, out, endpoint, repoInfo, tag, sf, auth); err != nil {
			return err
		} else if downloaded {
			layersDownloaded = true
		}
	}

	requestedTag := repoInfo.CanonicalName
	if len(tag) > 0 {
		requestedTag = utils.ImageReference(repoInfo.CanonicalName, tag)
	}
	WriteStatus(requestedTag, out, sf, layersDownloaded)
	return nil
}

func (s *TagStore) pullV2Repository(eng *engine.Engine, r *registry.Session, out io.Writer, repoInfo *registry.RepositoryInfo, tag string, sf *utils.StreamFormatter, parallel bool) error {
	endpoint, err := r.V2RegistryEndpoint(repoInfo.Index)
	if err != nil {
		return fmt.Errorf("error getting registry endpoint: %s", err)
	}
	auth, err := r.GetV2Authorization(endpoint, repoInfo.RemoteName, true)
	if err != nil {
		return fmt.Errorf("error getting authorization: %s", err)
	}
	var layersDownloaded bool
	if tag == "" {
		log.Debugf("Pulling tag list from V2 registry for %s", repoInfo.CanonicalName)
		tags, err := r.GetV2RemoteTags(endpoint, repoInfo.RemoteName, auth)
		if err != nil {
			return err
		}
		if len(tags) == 0 {
			return registry.ErrDoesNotExist
		}
		for _, t := range tags {
			if downloaded, err := s.pullV2Tag(eng, r, out, endpoint, repoInfo, t, sf, parallel, auth); err != nil {
				return err
			} else if downloaded {
				layersDownloaded = true
			}
		}
	} else {
		if downloaded, err := s.pullV2Tag(eng, r, out, endpoint, repoInfo, tag, sf, parallel, auth); err != nil {
			return err
		} else if downloaded {
			layersDownloaded = true
		}
	}

	requestedTag := repoInfo.CanonicalName
	if len(tag) > 0 {
		requestedTag = repoInfo.CanonicalName + ":" + tag
	}
	WriteStatus(requestedTag, out, sf, layersDownloaded)
	return nil
}

func (s *TagStore) pushRepository(r *registry.Session, out io.Writer, localName, remoteName string, localRepo map[string]string, tag string, sf *utils.StreamFormatter) error {
	out = utils.NewWriteFlusher(out)
	log.Debugf("Local repo: %s", localRepo)
	imgList, tagsByImage, err := s.getImageList(localRepo, tag)
	if err != nil {
		return err
	}

	out.Write(sf.FormatStatus("", "Sending image list"))

	var (
		repoData   *registry.RepositoryData
		imageIndex []*registry.ImgData
	)

	for _, imgId := range imgList {
		if tags, exists := tagsByImage[imgId]; exists {
			// If an image has tags you must add an entry in the image index
			// for each tag
			for _, tag := range tags {
				imageIndex = append(imageIndex, &registry.ImgData{
					ID:  imgId,
					Tag: tag,
				})
			}
		} else {
			// If the image does not have a tag it still needs to be sent to the
			// registry with an empty tag so that it is accociated with the repository
			imageIndex = append(imageIndex, &registry.ImgData{
				ID:  imgId,
				Tag: "",
			})

		}
	}

	log.Debugf("Preparing to push %s with the following images and tags", localRepo)
	for _, data := range imageIndex {
		log.Debugf("Pushing ID: %s with Tag: %s", data.ID, data.Tag)
	}

	// Register all the images in a repository with the registry
	// If an image is not in this list it will not be associated with the repository
	repoData, err = r.PushImageJSONIndex(remoteName, imageIndex, false, nil)
	if err != nil {
		return err
	}

	nTag := 1
	if tag == "" {
		nTag = len(localRepo)
	}
	for _, ep := range repoData.Endpoints {
		out.Write(sf.FormatStatus("", "Pushing repository %s (%d tags)", localName, nTag))

		for _, imgId := range imgList {
			if r.LookupRemoteImage(imgId, ep, repoData.Tokens) {
				out.Write(sf.FormatStatus("", "Image %s already pushed, skipping", utils.TruncateID(imgId)))
			} else {
				if _, err := s.pushImage(r, out, remoteName, imgId, ep, repoData.Tokens, sf); err != nil {
					// FIXME: Continue on error?
					return err
				}
			}

			for _, tag := range tagsByImage[imgId] {
				out.Write(sf.FormatStatus("", "Pushing tag for rev [%s] on {%s}", utils.TruncateID(imgId), ep+"repositories/"+remoteName+"/tags/"+tag))

				if err := r.PushRegistryTag(remoteName, imgId, tag, ep, repoData.Tokens); err != nil {
					return err
				}
			}
		}
	}

	if _, err := r.PushImageJSONIndex(remoteName, imageIndex, true, repoData.Endpoints); err != nil {
		return err
	}

	return nil
}

func (s *TagStore) pullV2Tag(eng *engine.Engine, r *registry.Session, out io.Writer, localName, remoteName, tag string, sf *utils.StreamFormatter, parallel bool) (bool, error) {
	log.Debugf("Pulling tag from V2 registry: %q", tag)
	manifestBytes, err := r.GetV2ImageManifest(remoteName, tag, nil)
	if err != nil {
		return false, err
	}

	manifest, verified, err := s.verifyManifest(eng, manifestBytes)
	if err != nil {
		return false, fmt.Errorf("error verifying manifest: %s", err)
	}

	if len(manifest.FSLayers) != len(manifest.History) {
		return false, fmt.Errorf("length of history not equal to number of layers")
	}

	if verified {
		out.Write(sf.FormatStatus(localName+":"+tag, "The image you are pulling has been verified"))
	} else {
		out.Write(sf.FormatStatus(tag, "Pulling from %s", localName))
	}

	if len(manifest.FSLayers) == 0 {
		return false, fmt.Errorf("no blobSums in manifest")
	}

	downloads := make([]downloadInfo, len(manifest.FSLayers))

	for i := len(manifest.FSLayers) - 1; i >= 0; i-- {
		var (
			sumStr  = manifest.FSLayers[i].BlobSum
			imgJSON = []byte(manifest.History[i].V1Compatibility)
		)

		img, err := image.NewImgJSON(imgJSON)
		if err != nil {
			return false, fmt.Errorf("failed to parse json: %s", err)
		}
		downloads[i].img = img

		// Check if exists
		if s.graph.Exists(img.ID) {
			log.Debugf("Image already exists: %s", img.ID)
			continue
		}

		chunks := strings.SplitN(sumStr, ":", 2)
		if len(chunks) < 2 {
			return false, fmt.Errorf("expected 2 parts in the sumStr, got %#v", chunks)
		}
		sumType, checksum := chunks[0], chunks[1]
		out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Pulling fs layer", nil))

		downloadFunc := func(di *downloadInfo) error {
			log.Debugf("pulling blob %q to V1 img %s", sumStr, img.ID)

			if c, err := s.poolAdd("pull", "img:"+img.ID); err != nil {
				if c != nil {
					out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Layer already being pulled by another client. Waiting.", nil))
					<-c
					out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Download complete", nil))
				} else {
					log.Debugf("Image (id: %s) pull is already running, skipping: %v", img.ID, err)
				}
			} else {
				defer s.poolRemove("pull", "img:"+img.ID)
				tmpFile, err := ioutil.TempFile("", "GetV2ImageBlob")
				if err != nil {
					return err
				}

				r, l, err := r.GetV2ImageBlobReader(remoteName, sumType, checksum, nil)
				if err != nil {
					return err
				}
				defer r.Close()
				io.Copy(tmpFile, utils.ProgressReader(r, int(l), out, sf, false, utils.TruncateID(img.ID), "Downloading"))

				out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Download complete", nil))

				log.Debugf("Downloaded %s to tempfile %s", img.ID, tmpFile.Name())
				di.tmpFile = tmpFile
				di.length = l
				di.downloaded = true
			}
			di.imgJSON = imgJSON

			return nil
		}

		if parallel {
			downloads[i].err = make(chan error)
			go func(di *downloadInfo) {
				di.err <- downloadFunc(di)
			}(&downloads[i])
		} else {
			err := downloadFunc(&downloads[i])
			if err != nil {
				return false, err
			}
//.........这里部分代码省略.........

func (s *TagStore) pullMRepository(r *registry.Session, out io.Writer, containerID, containerImage, localName, remoteName, askedTag string, sf *utils.StreamFormatter, parallel bool, mirrors []string) error {
	out.Write(sf.FormatStatus("", "Pulling (parallel:%v) repository %s:%s", parallel, localName, askedTag))

	if askedTag == "" {
		return fmt.Errorf("Error: tag is empty")
	}

	repoData, err := r.GetRepositoryData(remoteName)
	if err != nil {
		if strings.Contains(err.Error(), "HTTP code: 404") {
			return fmt.Errorf("Error: image %s not found", remoteName)
		}
		// Unexpected HTTP error
		return err
	}

	log.Debugf("Retrieving the tag list")
	tagsList, err := r.GetRemoteTags(repoData.Endpoints, remoteName, repoData.Tokens)
	if err != nil {
		log.Errorf("%v", err)
		return err
	}

	id, exists := tagsList[askedTag]
	if !exists {
		return fmt.Errorf("Tag %s not found in repository %s", askedTag, localName)
	}
	img, exists := repoData.ImgList[id]
	if !exists {
		return fmt.Errorf("Image ID %s not found in repository %s", id, localName)
	}
	img.Tag = askedTag

	var lastErr error
	success := false
	var is_downloaded bool
	if mirrors != nil {
		for _, ep := range mirrors {
			out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Pulling and merging image (%s) from %s, mirror: %s", img.Tag, localName, ep), nil))
			if is_downloaded, err = s.pullAndMergeImage(r, out, containerID, containerImage, img.ID, ep, repoData.Tokens, sf); err != nil {
				// Don't report errors when pulling from mirrors.
				log.Debugf("Error pulling and merging image (%s) from %s, mirror: %s, %s", img.Tag, localName, ep, err)
				continue
			}
			success = true
			break
		}
	}
	if !success {
		for _, ep := range repoData.Endpoints {
			out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Pulling and merging image (%s) from %s, endpoint: %s", img.Tag, localName, ep), nil))
			if is_downloaded, err = s.pullAndMergeImage(r, out, containerID, containerImage, img.ID, ep, repoData.Tokens, sf); err != nil {
				// It's not ideal that only the last error is returned, it would be better to concatenate the errors.
				// As the error is also given to the output stream the user will see the error.
				lastErr = err
				out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Error pulling and merging image (%s) from %s, endpoint: %s, %s", img.Tag, localName, ep, err), nil))
				continue
			}
			success = true
			break
		}
	}
	if !success {
		err := fmt.Errorf("Error pulling and merging image (%s) from %s, %v", img.Tag, localName, lastErr)
		out.Write(sf.FormatProgress(utils.TruncateID(img.ID), err.Error(), nil))
		return err
	}
	out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Layer is downloaded ? %v", is_downloaded), nil))
	out.Write(sf.FormatProgress(utils.TruncateID(img.ID), "Complete", nil))

	if err = s.Set(localName, img.Tag, img.ID, true); err != nil {
		return err
	}

	return nil
}

func (s *TagStore) pullAndMergeImage(r *registry.Session, out io.Writer, containerID, containerImage, imgID, endpoint string, token []string, sf *utils.StreamFormatter) (bool, error) {
	newHistory, err := r.GetRemoteHistory(imgID, endpoint, token)
	if err != nil {
		return false, err
	}
	oldHistory, err := r.GetRemoteHistory(containerImage, endpoint, token)
	if err != nil {
		return false, err
	}
	// Compare the differences between the two image
	compareHistory := make(map[string]string, len(oldHistory))
	for _, id := range oldHistory {
		compareHistory[id] = id
	}
	var history []string
	for _, id := range newHistory {
		if _, ok := compareHistory[id]; !ok {
			history = append(history, id)
		}
	}

	layers_downloaded := false
	for i := len(history) - 1; i >= 0; i-- {
		id := history[i]

		// ensure no two downloads of the same layer happen at the same time
		if c, err := s.poolAdd("pull", "layer:"+id); err != nil {
			log.Debugf("Image (id: %s) pull is already running, skipping: %v", id, err)
			<-c
		}
		defer s.poolRemove("pull", "layer:"+id)

		out.Write(sf.FormatProgress(utils.TruncateID(id), "Pulling metadata", nil))
		var (
			imgJSON []byte
			imgSize int
			err     error
			img     *image.Image
		)
		retries := 5
		for j := 1; j <= retries; j++ {
			imgJSON, imgSize, err = r.GetRemoteImageJSON(id, endpoint, token)
			if err != nil && j == retries {
				out.Write(sf.FormatProgress(utils.TruncateID(id), "Error pulling dependent layers", nil))
				return layers_downloaded, err
			} else if err != nil {
				time.Sleep(time.Duration(j) * 500 * time.Millisecond)
				continue
			}
			img, err = image.NewImgJSON(imgJSON)
			layers_downloaded = true
			if err != nil && j == retries {
				out.Write(sf.FormatProgress(utils.TruncateID(id), "Error pulling dependent layers", nil))
				return layers_downloaded, fmt.Errorf("Failed to parse json: %s", err)
			} else if err != nil {
				time.Sleep(time.Duration(j) * 500 * time.Millisecond)
				continue
			} else {
				break
			}
		}

		for j := 1; j <= retries; j++ {
			// Get the layer
			status := "Pulling fs layer"
			if j > 1 {
				status = fmt.Sprintf("Pulling fs layer [retries: %d]", j)
			}
			out.Write(sf.FormatProgress(utils.TruncateID(id), status, nil))
			layer, err := r.GetRemoteImageLayer(img.ID, endpoint, token, int64(imgSize))
			if uerr, ok := err.(*url.Error); ok {
				err = uerr.Err
			}
			if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
				time.Sleep(time.Duration(j) * 500 * time.Millisecond)
				continue
			} else if err != nil {
				out.Write(sf.FormatProgress(utils.TruncateID(id), "Error pulling dependent layers", nil))
				return layers_downloaded, err
			}
			layers_downloaded = true
			defer layer.Close()
			if !s.graph.Exists(id) {
				// register when first pull layer
				err = s.graph.Register(img, imgJSON,
					utils.ProgressReader(layer, imgSize, out, sf, false, utils.TruncateID(id), "Downloading"))
				if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else if err != nil {
					out.Write(sf.FormatProgress(utils.TruncateID(id), "Error downloading dependent layers", nil))
					return layers_downloaded, err
				}
			}
			// add layer to container
			dest := path.Join(s.graph.Driver().MountPath(), containerID, "rootfs")
			out.Write(sf.FormatProgress(utils.TruncateID(id), fmt.Sprintf("Merge layer to container rootfs %s", dest), nil))
			err = archive.ApplyLayer(dest, layer)
			if err != nil && j == retries {
				out.Write(sf.FormatProgress(utils.TruncateID(id), "Error merge layers", nil))
//.........这里部分代码省略.........

// TODO rewrite this whole PoC
func main() {
	flag.Usage = func() {
		flag.PrintDefaults()
	}
	flag.Parse()
	if debug {
		os.Setenv("DEBUG", "1")
		log.SetLevel(log.DebugLevel)
	}
	if flag.NArg() == 0 {
		fmt.Println("ERROR: no image names provided")
		flag.Usage()
		os.Exit(1)
	}

	// make tempDir
	tempDir, err := ioutil.TempDir("", "docker-fetch-")
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	defer os.RemoveAll(tempDir)

	fetcher := NewFetcher(tempDir)
	sc := registry.NewServiceConfig(rOptions)

	for _, arg := range flag.Args() {
		remote, tagName := parsers.ParseRepositoryTag(arg)
		if tagName == "" {
			tagName = "latest"
		}

		repInfo, err := sc.NewRepositoryInfo(remote)
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		log.Debugf("%#v %q\n", repInfo, tagName)

		idx, err := repInfo.GetEndpoint()
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		fmt.Fprintf(os.Stderr, "Pulling %s:%s from %s\n", repInfo.RemoteName, tagName, idx)

		var session *registry.Session
		if s, ok := fetcher.sessions[idx.String()]; ok {
			session = s
		} else {
			// TODO(vbatts) obviously the auth and http factory shouldn't be nil here
			session, err = registry.NewSession(nil, nil, idx, timeout)
			if err != nil {
				fmt.Fprintln(os.Stderr, err)
				os.Exit(1)
			}
		}

		rd, err := session.GetRepositoryData(repInfo.RemoteName)
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		log.Debugf("rd: %#v", rd)

		// produce the "repositories" file for the archive
		if _, ok := fetcher.repositories[repInfo.RemoteName]; !ok {
			fetcher.repositories[repInfo.RemoteName] = graph.Repository{}
		}
		log.Debugf("repositories: %#v", fetcher.repositories)

		if len(rd.Endpoints) == 0 {
			log.Fatalf("expected registry endpoints, but received none from the index")
		}

		tags, err := session.GetRemoteTags(rd.Endpoints, repInfo.RemoteName, rd.Tokens)
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		if hash, ok := tags[tagName]; ok {
			fetcher.repositories[repInfo.RemoteName][tagName] = hash
		}
		log.Debugf("repositories: %#v", fetcher.repositories)

		imgList, err := session.GetRemoteHistory(fetcher.repositories[repInfo.RemoteName][tagName], rd.Endpoints[0], rd.Tokens)
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		log.Debugf("imgList: %#v", imgList)

		for _, imgID := range imgList {
			// pull layers and jsons
			buf, _, err := session.GetRemoteImageJSON(imgID, rd.Endpoints[0], rd.Tokens)
			if err != nil {
				fmt.Fprintln(os.Stderr, err)
				os.Exit(1)
			}
//.........这里部分代码省略.........