Method fetch

client/pull.go:192–286

(ctx context.Context, rCtx *RemoteContext, ref string, limit int)

}

func (c *Client) fetch(ctx context.Context, rCtx *RemoteContext, ref string, limit int) (images.Image, error) {
	ctx, span := tracing.StartSpan(ctx, tracing.Name(pullSpanPrefix, "fetch"))
	defer span.End()
	store := c.ContentStore()
	name, desc, err := rCtx.Resolver.Resolve(ctx, ref)
	if err != nil {
		return images.Image{}, fmt.Errorf("failed to resolve reference %q: %w", ref, err)
	}

	fetcher, err := rCtx.Resolver.Fetcher(ctx, name)
	if err != nil {
		return images.Image{}, fmt.Errorf("failed to get fetcher for %q: %w", name, err)
	}

	var (
		handler images.Handler

		isConvertible bool
		converterFunc func(context.Context, ocispec.Descriptor) (ocispec.Descriptor, error)
		limiter       *semaphore.Weighted
	)
	if desc.MediaType == images.MediaTypeDockerSchema1Manifest {
		return images.Image{}, fmt.Errorf("%w: media type %q is no longer supported since containerd v2.1, please rebuild the image as %q or %q",
			errdefs.ErrNotImplemented,
			images.MediaTypeDockerSchema1Manifest, images.MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest)
	}
	// Get all the children for a descriptor
	childrenHandler := images.ChildrenHandler(store)
	if rCtx.ReferrersProvider != nil {
		childrenHandler = images.SetReferrers(rCtx.ReferrersProvider, childrenHandler)
	}
	// Set any children labels for that content
	childrenHandler = images.SetChildrenMappedLabels(store, childrenHandler, rCtx.ChildLabelMap)
	if rCtx.AllMetadata {
		// Filter manifests by platforms but allow to handle manifest
		// and configuration for not-target platforms
		childrenHandler = remotes.FilterManifestByPlatformHandler(childrenHandler, rCtx.PlatformMatcher)
	} else {
		// Filter children by platforms if specified.
		childrenHandler = images.FilterPlatforms(childrenHandler, rCtx.PlatformMatcher)
	}
	// Sort and limit manifests if a finite number is needed
	if limit > 0 {
		childrenHandler = images.LimitManifests(childrenHandler, rCtx.PlatformMatcher, limit)
	}

	// set isConvertible to true if there is application/octet-stream media type
	convertibleHandler := images.HandlerFunc(
		func(_ context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
			if desc.MediaType == docker.LegacyConfigMediaType {
				isConvertible = true
			}

			return []ocispec.Descriptor{}, nil
		},
	)

	appendDistSrcLabelHandler, err := docker.AppendDistributionSourceLabel(store, ref)