Function annotateDistributionSourceHandler

core/remotes/handlers.go:358–402

annotateDistributionSourceHandler add distribution source label into annotation of config or blob descriptor.

(f images.HandlerFunc, provider content.InfoProvider)

// annotateDistributionSourceHandler add distribution source label into
// annotation of config or blob descriptor.
func annotateDistributionSourceHandler(f images.HandlerFunc, provider content.InfoProvider) images.HandlerFunc {
	return func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
		children, err := f(ctx, desc)
		if err != nil {
			return nil, err
		}

		// Distribution source is only used for config or blob but may be inherited from
		// a manifest or manifest list
		if !images.IsManifestType(desc.MediaType) && !images.IsIndexType(desc.MediaType) {
			return children, nil
		}

		parentSourceAnnotations := desc.Annotations
		var parentLabels map[string]string
		if pi, err := provider.Info(ctx, desc.Digest); err != nil {
			if !errdefs.IsNotFound(err) {
				return nil, err
			}
		} else {
			parentLabels = pi.Labels
		}

		for i := range children {
			child := children[i]

			info, err := provider.Info(ctx, child.Digest)
			if err != nil {
				if !errdefs.IsNotFound(err) {
					return nil, err
				}
			}
			copyDistributionSourceLabels(info.Labels, &child)

			// Annotate with parent labels for cross repo mount or fetch.
			// Parent sources may apply to all children since most registries
			// enforce that children exist before the manifests.
			copyDistributionSourceLabels(parentSourceAnnotations, &child)
			copyDistributionSourceLabels(parentLabels, &child)

			children[i] = child
		}
		return children, nil
	}
}

func copyDistributionSourceLabels(from map[string]string, to *ocispec.Descriptor) {
	for k, v := range from {