682151b166
To support resumable download, the fetcher for a remote must implement `io.Seeker`. If implemented the `content.Copy` function will detect the seeker and begin from where the download was terminated by a previous attempt. Signed-off-by: Stephen J Day <stephen.day@docker.com>
123 lines
3.2 KiB
Go
123 lines
3.2 KiB
Go
package docker
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import (
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"context"
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"fmt"
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"io"
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"net/http"
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"path"
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"strings"
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"github.com/containerd/containerd/errdefs"
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"github.com/containerd/containerd/images"
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"github.com/containerd/containerd/log"
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ocispec "github.com/opencontainers/image-spec/specs-go/v1"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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)
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type dockerFetcher struct {
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*dockerBase
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}
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func (r dockerFetcher) Fetch(ctx context.Context, desc ocispec.Descriptor) (io.ReadCloser, error) {
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ctx = log.WithLogger(ctx, log.G(ctx).WithFields(
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logrus.Fields{
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"base": r.base.String(),
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"digest": desc.Digest,
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},
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))
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urls, err := r.getV2URLPaths(ctx, desc)
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if err != nil {
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return nil, err
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}
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ctx, err = contextWithRepositoryScope(ctx, r.refspec, false)
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if err != nil {
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return nil, err
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}
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return newHTTPReadSeeker(desc.Size, func(offset int64) (io.ReadCloser, error) {
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for _, u := range urls {
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rc, err := r.open(ctx, u, desc.MediaType, offset)
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if err != nil {
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if errdefs.IsNotFound(err) {
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continue // try one of the other urls.
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}
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return nil, err
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}
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return rc, nil
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}
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return nil, errors.Wrapf(errdefs.ErrNotFound,
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"could not fetch content descriptor %v (%v) from remote",
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desc.Digest, desc.MediaType)
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})
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}
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func (r dockerFetcher) open(ctx context.Context, u, mediatype string, offset int64) (io.ReadCloser, error) {
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req, err := http.NewRequest(http.MethodGet, u, nil)
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if err != nil {
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return nil, err
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}
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req.Header.Set("Accept", strings.Join([]string{mediatype, `*`}, ", "))
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if offset > 0 {
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// TODO(stevvooe): Only set this header in response to the
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// "Accept-Ranges: bytes" header.
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req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset))
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}
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resp, err := r.doRequestWithRetries(ctx, req, nil)
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if err != nil {
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return nil, err
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}
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if resp.StatusCode > 299 {
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// TODO(stevvooe): When doing a offset specific request, we should
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// really distinguish between a 206 and a 200. In the case of 200, we
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// can discard the bytes, hiding the seek behavior from the
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// implementation.
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resp.Body.Close()
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if resp.StatusCode == http.StatusNotFound {
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return nil, errors.Wrapf(errdefs.ErrNotFound, "content at %v not found", u)
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}
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return nil, errors.Errorf("unexpected status code %v: %v", u, resp.Status)
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}
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return resp.Body, nil
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}
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// getV2URLPaths generates the candidate urls paths for the object based on the
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// set of hints and the provided object id. URLs are returned in the order of
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// most to least likely succeed.
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func (r *dockerFetcher) getV2URLPaths(ctx context.Context, desc ocispec.Descriptor) ([]string, error) {
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var urls []string
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if len(desc.URLs) > 0 {
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// handle fetch via external urls.
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for _, u := range desc.URLs {
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log.G(ctx).WithField("url", u).Debug("adding alternative url")
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urls = append(urls, u)
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}
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}
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switch desc.MediaType {
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case images.MediaTypeDockerSchema2Manifest, images.MediaTypeDockerSchema2ManifestList,
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images.MediaTypeDockerSchema1Manifest,
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ocispec.MediaTypeImageManifest, ocispec.MediaTypeImageIndex:
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urls = append(urls, r.url(path.Join("manifests", desc.Digest.String())))
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}
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// always fallback to attempting to get the object out of the blobs store.
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urls = append(urls, r.url(path.Join("blobs", desc.Digest.String())))
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return urls, nil
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}
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