1、mtail:从日志中提取指标，发送到时间序列数据库
https://blog.csdn.net/weixin_34255793/article/details/89723969
https://www.cnblogs.com/rongfengliang/p/10117663.html

mtail基于RE2

2、收集apache日志

apache_combined.mtail

Parser for the common apache "NCSA extended/combined" log format

LogFormat "%h %l %u %t "%r" %>s %b "%{Referer}i" "%{User-agent}i"

counter apache_http_requests_total by request_method, http_version, request_status
counter apache_http_bytes_total by request_method, http_version, request_status

/^/ +
/(?P<hostname>[0-9A-Za-z.-]+) / + # %h
/(?P<remote_logname>[0-9A-Za-z-]+) / + # %l
/(?P<remote_username>[0-9A-Za-z-]+) / + # %u
/(?P<timestamp>[\d{2}/\w{3}/\d{4}:\d{2}:\d{2}:\d{2} (+|-)\d{4}]) / + # %u
/"(?P<request_method>[A-Z]+) (?P<URI>\S+) (?P<http_version>HTTP/[0-9.]+)" / + # "%r"
/(?P<request_status>\d{3}) / + # %>s
/(?P<response_size>\d+) / + # %b
/"(?P<referer>\S+)" / + # "%{Referer}i"
/"(?P<user_agent>[[:print:]]+)"/ + # "%{User-agent}i"
/ $/ { apache_http_requests_total[$ request_method][ $http_version][$ request_status]++
apache_http_bytes_total[ $request_method][$ http_version][ $request_status] +=$ response_size
}