Method GetManifest

docker/docker_image_src.go:227–239

GetManifest returns the image's manifest along with its MIME type (which may be empty when it can't be determined but the manifest is available). It may use a remote (= slow) service. If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve (when the primary m

(ctx context.Context, instanceDigest *digest.Digest)

// If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve (when the primary manifest is a manifest list);
// this never happens if the primary manifest is not a manifest list (e.g. if the source never returns manifest lists).
func (s *dockerImageSource) GetManifest(ctx context.Context, instanceDigest *digest.Digest) ([]byte, string, error) {
	if instanceDigest != nil {
		if err := instanceDigest.Validate(); err != nil { // Make sure instanceDigest.String() does not contain any unexpected characters
			return nil, "", err
		}
		return s.fetchManifest(ctx, instanceDigest.String())
	}
	err := s.ensureManifestIsLoaded(ctx)
	if err != nil {
		return nil, "", err
	}
	return s.cachedManifest, s.cachedManifestMIMEType, nil
}

// fetchManifest fetches a manifest for tagOrDigest.
// The caller is responsible for ensuring tagOrDigest uses the expected format.