private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
    FullHttpResponse response =
        new DefaultFullHttpResponse(
            HttpVersion.HTTP_1_1,
            status,
            Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
    response.headers().set(HttpHeaderConstants.CONTENT_TYPE, "text/plain; charset=UTF-8");

    // Close the connection as soon as the error message is sent.
    ctx.write(response).addListener(ChannelFutureListener.CLOSE);
  }