Method blobExists

docker/docker_image_dest.go:233–261

blobExists returns true iff repo contains a blob with digest, and if so, also its size. If the destination does not contain the blob, or it is unknown, blobExists ordinarily returns (false, -1, nil); it returns a non-nil error only on an unexpected failure.

(ctx context.Context, repo reference.Named, digest digest.Digest, extraScope *authScope)

// If the destination does not contain the blob, or it is unknown, blobExists ordinarily returns (false, -1, nil);
// it returns a non-nil error only on an unexpected failure.
func (d *dockerImageDestination) blobExists(ctx context.Context, repo reference.Named, digest digest.Digest, extraScope *authScope) (bool, int64, error) {
	if err := digest.Validate(); err != nil { // Make sure digest.String() does not contain any unexpected characters
		return false, -1, err
	}
	checkPath := fmt.Sprintf(blobsPath, reference.Path(repo), digest.String())
	logrus.Debugf("Checking %s", checkPath)
	res, err := d.c.makeRequest(ctx, http.MethodHead, checkPath, nil, nil, v2Auth, extraScope)
	if err != nil {
		return false, -1, err
	}
	defer res.Body.Close()
	switch res.StatusCode {
	case http.StatusOK:
		size, err := getBlobSize(res)
		if err != nil {
			return false, -1, fmt.Errorf("determining size of blob %s in %s: %w", digest, repo.Name(), err)
		}
		logrus.Debugf("... already exists")
		return true, size, nil
	case http.StatusUnauthorized:
		logrus.Debugf("... not authorized")
		return false, -1, fmt.Errorf("checking whether a blob %s exists in %s: %w", digest, repo.Name(), registryHTTPResponseToError(res))
	case http.StatusNotFound:
		logrus.Debugf("... not present")
		return false, -1, nil
	default:
		return false, -1, fmt.Errorf("checking whether a blob %s exists in %s: %w", digest, repo.Name(), registryHTTPResponseToError(res))
	}
}

// mountBlob tries to mount blob srcDigest from srcRepo to the current destination.
func (d *dockerImageDestination) mountBlob(ctx context.Context, srcRepo reference.Named, srcDigest digest.Digest, extraScope *authScope) error {