Method __fetch

src/uri/fetchers/docker.cpp:834–948

Future<Nothing> DockerFetcherPluginProcess::__fetch(
    const URI& uri,
    const string& directory,
    const http::Headers& authHeaders,
    const http::Response& response)
{
  if (response.code != http::Status::OK) {
    return Failure(
        "Unexpected HTTP response '" + response.status + "' "
        "when trying to get the manifest");
  }

  CHECK_EQ(response.type, http::Response::BODY);

  Option<string> contentType = response.headers.get("Content-Type");
  if (contentType.isNone()) {
    return Failure("No Content-Type present");
  }

  // NOTE: Docker supports the following five media types.
  //
  // V2 schema 1 manifest:
  // 1. application/vnd.docker.distribution.manifest.v1+json
  // 2. application/vnd.docker.distribution.manifest.v1+prettyjws
  // 3. application/json
  //
  // For more details, see:
  // https://docs.docker.com/registry/spec/manifest-v2-1/
  //
  // V2 schema 2 manifest:
  // 1. application/vnd.docker.distribution.manifest.v2+json
  // 2. application/vnd.docker.distribution.manifest.list.v2+json
  //    (manifest list is not supported yet)
  //
  // For more details, see:
  // https://docs.docker.com/registry/spec/manifest-v2-2/
  bool isV2Schema1 =
    strings::startsWith(
        contentType.get(),
        "application/vnd.docker.distribution.manifest.v1") ||
    strings::startsWith(
        contentType.get(),
        "application/json");

  // TODO(gilbert): Support manifest list (fat manifest) in V2 Schema2.
  bool isV2Schema2 =
    contentType.get() == "application/vnd.docker.distribution.manifest.v2+json";

  if (isV2Schema1) {
    // Parse V2 schema 1 image manifest.
    Try<spec::v2::ImageManifest> manifest = spec::v2::parse(response.body);
    if (manifest.isError()) {
      return Failure(
          "Failed to parse the V2 Schema 1 image manifest: " +
          manifest.error());
    }

    // Save manifest to 'directory'.