如何优雅打印nginx header和body

worker_processes  1;
error_log logs/error.log;
events {
    worker_connections 1024;
}
http {
    log_format log_req_resp '$remote_addr - $remote_user [$time_local] '
        '"$request" $status $body_bytes_sent '
        '"$http_referer" "$http_user_agent" $request_time req_body:"$request_body"' 
        ' resp_body:"$resp_body" resp_header:"$resp_header"';

    server {
        listen 8082;
        access_log logs/access.log log_req_resp;

        set $resp_header "";
        header_filter_by_lua '
            local h = ngx.resp.get_headers()
            for k, v in pairs(h) do
            ngx.var.resp_header=ngx.var.resp_header..k..": "..v
            end
        ';

        lua_need_request_body on;

        set $resp_body "";
        body_filter_by_lua '
            local resp_body = string.sub(ngx.arg[1], 1, 1000)
            ngx.ctx.buffered = (ngx.ctx.buffered or "") .. resp_body
            if ngx.arg[2] then
                ngx.var.resp_body = ngx.ctx.buffered
            end
        ';

        location / {
            echo "Hello World!";
        }
    }
}