nginx with response out

nginx.lua

http {
    include       mime.types;
    default_type  application/octet-stream;

    keepalive_timeout  65;

    log_format log_1 'x $request_body - $resp_body';

    server {
        listen       8080;
        access_log logs/access.log log_1;

        lua_need_request_body on;
        set $resp_body "";

        body_filter_by_lua_block {
                local resp_body = ngx.arg[1]
                ngx.ctx.buffered = (ngx.ctx.buffered or "") .. resp_body
                if ngx.arg[2] then
                        ngx.var.resp_body = ngx.ctx.buffered
                end
        }

        location / {
                default_type "text/plain";
                content_by_lua_block {
                        ngx.print("hello");
                }
        }
    }
}