nginx日志格式化为json

log_format json '{"@timestamp":"$time_iso8601",'
                    '"@version":"1",'
                    '"client":"$remote_addr",'
                    '"url":"$uri",'
                    '"status":"$status",'
                    '"domain":"$host",'
                    '"size":"$body_bytes_sent",'
                    '"responsetime":"$request_time",'
                    '"referer":"$http_referer",'
                    '"ua":"$http_user_agent"'
                    '}';