1.grok表达式

Grok 是 Logstash 最重要的插件。你可以在 grok 里直接使用或应用预定义的表达式名称，grok 支持把预定义的 grok 表达式 写入到文件中，官方提供的预定义 grok 表达式见：https://github.com/logstash-plugins/logstash-patterns-core/blob/master/patterns/grok-patternss。

最直观的grok语法使用参见：ELK应用之Logstash；
https://www.elastic.co/guide/en/logstash/current/plugins-filters-grok.html，这里不做赘述。

下面是从官方文件中摘抄的最简单但是足够说明用法的示例：

USERNAME [a-zA-Z0-9._-]+
USER %{USERNAME}

第一列是正则grok表达式的名称，可直接使用；第二列是普通的正则表达式；
第一行，用普通的正则表达式来定义一个 grok 表达式；第二行，通过打印赋值格式，用前面定义好的 grok 表达式来定义另一个 grok 表达式。（简单的说就是，名字和表达式，而且可嵌套使用）

grok 表达式使用的基本语法是下面这样的：

%{SYNTAX:SEMANTIC}

小贴士：SYNTAX是指预定义好的表达式的名字，SEMANTIC是指匹配之后要放的字段名字（自定义或随心所欲，只要自己能认识区分的）。

附录：

USERNAME [a-zA-Z0-9._-]+
USER %{USERNAME}
EMAILLOCALPART [a-zA-Z][a-zA-Z0-9_.+-=:]+
EMAILADDRESS %{EMAILLOCALPART}@%{HOSTNAME}
INT (?:[+-]?(?:[0-9]+))
BASE10NUM (?<![0-9.+-])(?>[+-]?(?:(?:[0-9]+(?:\.[0-9]+)?)|(?:\.[0-9]+)))
NUMBER (?:%{BASE10NUM})
BASE16NUM (?<![0-9A-Fa-f])(?:[+-]?(?:0x)?(?:[0-9A-Fa-f]+))
BASE16FLOAT \b(?<![0-9A-Fa-f.])(?:[+-]?(?:0x)?(?:(?:[0-9A-Fa-f]+(?:\.[0-9A-Fa-f]*)?)|(?:\.[0-9A-Fa-f]+)))\b

POSINT \b(?:[1-9][0-9]*)\b
NONNEGINT \b(?:[0-9]+)\b
WORD \b\w+\b
NOTSPACE \S+
SPACE \s*
DATA .*?
GREEDYDATA .*
QUOTEDSTRING (?>(?<!\\)(?>"(?>\\.|[^\\"]+)+"|""|(?>'(?>\\.|[^\\']+)+')|''|(?>`(?>\\.|[^\\`]+)+`)|``))
UUID [A-Fa-f0-9]{8}-(?:[A-Fa-f0-9]{4}-){3}[A-Fa-f0-9]{12}
# URN, allowing use of RFC 2141 section 2.3 reserved characters
URN urn:[0-9A-Za-z][0-9A-Za-z-]{0,31}:(?:%[0-9a-fA-F]{2}|[0-9A-Za-z()+,.:=@;$_!*'/?#-])+

# Networking
MAC (?:%{CISCOMAC}|%{WINDOWSMAC}|%{COMMONMAC})
CISCOMAC (?:(?:[A-Fa-f0-9]{4}\.){2}[A-Fa-f0-9]{4})
WINDOWSMAC (?:(?:[A-Fa-f0-9]{2}-){5}[A-Fa-f0-9]{2})
COMMONMAC (?:(?:[A-Fa-f0-9]{2}:){5}[A-Fa-f0-9]{2})
IPV6 ((([0-9A-Fa-f]{1,4}:){7}([0-9A-Fa-f]{1,4}|:))|(([0-9A-Fa-f]{1,4}:){6}(:[0-9A-Fa-f]{1,4}|((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){5}(((:[0-9A-Fa-f]{1,4}){1,2})|:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){4}(((:[0-9A-Fa-f]{1,4}){1,3})|((:[0-9A-Fa-f]{1,4})?:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){3}(((:[0-9A-Fa-f]{1,4}){1,4})|((:[0-9A-Fa-f]{1,4}){0,2}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){2}(((:[0-9A-Fa-f]{1,4}){1,5})|((:[0-9A-Fa-f]{1,4}){0,3}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){1}(((:[0-9A-Fa-f]{1,4}){1,6})|((:[0-9A-Fa-f]{1,4}){0,4}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(:(((:[0-9A-Fa-f]{1,4}){1,7})|((:[0-9A-Fa-f]{1,4}){0,5}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:)))(%.+)?
IPV4 (?<![0-9])(?:(?:[0-1]?[0-9]{1,2}|2[0-4][0-9]|25[0-5])[.](?:[0-1]?[0-9]{1,2}|2[0-4][0-9]|25[0-5])[.](?:[0-1]?[0-9]{1,2}|2[0-4][0-9]|25[0-5])[.](?:[0-1]?[0-9]{1,2}|2[0-4][0-9]|25[0-5]))(?![0-9])
IP (?:%{IPV6}|%{IPV4})
HOSTNAME \b(?:[0-9A-Za-z][0-9A-Za-z-]{0,62})(?:\.(?:[0-9A-Za-z][0-9A-Za-z-]{0,62}))*(\.?|\b)
IPORHOST (?:%{IP}|%{HOSTNAME})
HOSTPORT %{IPORHOST}:%{POSINT}

# paths
PATH (?:%{UNIXPATH}|%{WINPATH})
UNIXPATH (/([\w_%!$@:.,+~-]+|\\.)*)+
TTY (?:/dev/(pts|tty([pq])?)(\w+)?/?(?:[0-9]+))
WINPATH (?>[A-Za-z]+:|\\)(?:\\[^\\?*]*)+
URIPROTO [A-Za-z]([A-Za-z0-9+\-.]+)+
URIHOST %{IPORHOST}(?::%{POSINT:port})?
# uripath comes loosely from RFC1738, but mostly from what Firefox
# doesn't turn into %XX
URIPATH (?:/[A-Za-z0-9$.+!*'(){},~:;=@#%&_\-]*)+
#URIPARAM \?(?:[A-Za-z0-9]+(?:=(?:[^&]*))?(?:&(?:[A-Za-z0-9]+(?:=(?:[^&]*))?)?)*)?
URIPARAM \?[A-Za-z0-9$.+!*'|(){},~@#%&/=:;_?\-\[\]<>]*
URIPATHPARAM %{URIPATH}(?:%{URIPARAM})?
URI %{URIPROTO}://(?:%{USER}(?::[^@]*)?@)?(?:%{URIHOST})?(?:%{URIPATHPARAM})?

# Months: January, Feb, 3, 03, 12, December
MONTH \b(?:[Jj]an(?:uary|uar)?|[Ff]eb(?:ruary|ruar)?|[Mm](?:a|ä)?r(?:ch|z)?|[Aa]pr(?:il)?|[Mm]a(?:y|i)?|[Jj]un(?:e|i)?|[Jj]ul(?:y)?|[Aa]ug(?:ust)?|[Ss]ep(?:tember)?|[Oo](?:c|k)?t(?:ober)?|[Nn]ov(?:ember)?|[Dd]e(?:c|z)(?:ember)?)\b
MONTHNUM (?:0?[1-9]|1[0-2])
MONTHNUM2 (?:0[1-9]|1[0-2])
MONTHDAY (?:(?:0[1-9])|(?:[12][0-9])|(?:3[01])|[1-9])

# Days: Monday, Tue, Thu, etc...
DAY (?:Mon(?:day)?|Tue(?:sday)?|Wed(?:nesday)?|Thu(?:rsday)?|Fri(?:day)?|Sat(?:urday)?|Sun(?:day)?)

# Years?
YEAR (?>\d\d){1,2}
HOUR (?:2[0123]|[01]?[0-9])
MINUTE (?:[0-5][0-9])
# '60' is a leap second in most time standards and thus is valid.
SECOND (?:(?:[0-5]?[0-9]|60)(?:[:.,][0-9]+)?)
TIME (?!<[0-9])%{HOUR}:%{MINUTE}(?::%{SECOND})(?![0-9])
# datestamp is YYYY/MM/DD-HH:MM:SS.UUUU (or something like it)
DATE_US %{MONTHNUM}[/-]%{MONTHDAY}[/-]%{YEAR}
DATE_EU %{MONTHDAY}[./-]%{MONTHNUM}[./-]%{YEAR}
ISO8601_TIMEZONE (?:Z|[+-]%{HOUR}(?::?%{MINUTE}))
ISO8601_SECOND (?:%{SECOND}|60)
TIMESTAMP_ISO8601 %{YEAR}-%{MONTHNUM}-%{MONTHDAY}[T ]%{HOUR}:?%{MINUTE}(?::?%{SECOND})?%{ISO8601_TIMEZONE}?
DATE %{DATE_US}|%{DATE_EU}
DATESTAMP %{DATE}[- ]%{TIME}
TZ (?:[APMCE][SD]T|UTC)
DATESTAMP_RFC822 %{DAY} %{MONTH} %{MONTHDAY} %{YEAR} %{TIME} %{TZ}
DATESTAMP_RFC2822 %{DAY}, %{MONTHDAY} %{MONTH} %{YEAR} %{TIME} %{ISO8601_TIMEZONE}
DATESTAMP_OTHER %{DAY} %{MONTH} %{MONTHDAY} %{TIME} %{TZ} %{YEAR}
DATESTAMP_EVENTLOG %{YEAR}%{MONTHNUM2}%{MONTHDAY}%{HOUR}%{MINUTE}%{SECOND}

# Syslog Dates: Month Day HH:MM:SS
SYSLOGTIMESTAMP %{MONTH} +%{MONTHDAY} %{TIME}
PROG [\x21-\x5a\x5c\x5e-\x7e]+
SYSLOGPROG %{PROG:program}(?:\[%{POSINT:pid}\])?
SYSLOGHOST %{IPORHOST}
SYSLOGFACILITY <%{NONNEGINT:facility}.%{NONNEGINT:priority}>
HTTPDATE %{MONTHDAY}/%{MONTH}/%{YEAR}:%{TIME} %{INT}

# Shortcuts
QS %{QUOTEDSTRING}

# Log formats
SYSLOGBASE %{SYSLOGTIMESTAMP:timestamp} (?:%{SYSLOGFACILITY} )?%{SYSLOGHOST:logsource} %{SYSLOGPROG}:

# Log Levels
LOGLEVEL ([Aa]lert|ALERT|[Tt]race|TRACE|[Dd]ebug|DEBUG|[Nn]otice|NOTICE|[Ii]nfo|INFO|[Ww]arn?(?:ing)?|WARN?(?:ING)?|[Ee]rr?(?:or)?|ERR?(?:OR)?|[Cc]rit?(?:ical)?|CRIT?(?:ICAL)?|[Ff]atal|FATAL|[Ss]evere|SEVERE|EMERG(?:ENCY)?|[Ee]merg(?:ency)?)

2.截取指定字符

grok正则表达式：(?<temMsg>(.*)(?=Report)/?) 获取Report之前的字符作为temMsg字段的值
grok正则表达式：(?<temMsg>(?=Report)(.*)/?) 获取Report之后的字符作为temMsg字段的值
grok{
        match => { 
                 #截取<Report>之前的字符作为temMsg字段的值
                "message" => "(?<temMsg>(.*)(?=Report)/?)" 
            }
    }
这个是截取特定的字符集日志，要日志中包含了"Report"关键字，关键字根据实际替换即可
（注：表达式中(?=Report)中的等于"="符号如果换成"<="这表示就不包含本身了，例如(?<temMsg>(.*)(?=Report)/?)可以写成(?<temMsg>(.*)(?<=Report)/?)这样输出的结果就不包含Report了，同理下面的一样）

grok正则表达式：(?<temMsg>(?<=report).*?(?=msg)) 截取report和msg之间的值,不包含report和msg本身
grok正则表达式：(?<temMsg>(report).*?(?=msg)) 截取 包含report但不包含msg
grok正则表达式：(?<temMsg>(?<=report).*?(msg))截取  不包含report但包含msg
grok正则表达式：(?<temMsg>(report).*?(msg|request))输出以report开头,以msg或者以request结尾的所有包含头尾信息
grok正则表达式：(?<temMsg>(report).*?(?=(msg|request)))输出以report开头,以msg或者以request结尾的不包含头尾信息
grok{
        match => { 
                 #截取<Report>之后的和<msg>之前的值作为temMsg字段的值
                "message" => "(?<temMsg>(?<=report).*?(?=msg))" 
            }
    }
这个是截取特定的字符集日志，要日志中包含了【report和msg和request】关键字
之间的表达式只要替换一下就可以使用了
（注过个表达式中出现异常，在单个的字符串中可以将小括号【()】去掉，例如：(report).*?(?=msg) 可以写成report.*?(?=msg)）

grok正则表达式：(?<MYELF>([\s\S]{500}))
 grok{
       match => {
              #截取日志500个字符 作为MYELF的值
              "message" => "(?<MYELF>([\s\S]{500}))"  
             }
     }
    对有所日志截取500个字符，可以加入if()做为判断条件，根据自身项目来

grok正则表达式：%{LOGLEVEL:level}
grok {
        #这个patterns_dir大家都应该正对 单独写表达式的地方
        #patterns_dir => "/usr/local/nlp/logstash-6.0.1/config/patterns"
                match => [
                        "message","%{LOGLEVEL:level}"         
                ]
        }
  这个比较简单 就不多说了

结合上面的 这个是对level级别的日志做判断 如果日志中含有DEBUG的，就drop掉
if [level] == "DEBUG" {
       drop { }
}
这个其实和上面差不多，加了一个【~】表示对单条的前后日志做匹配
if[message]=~"ASPECT"{
       drop { }
}

这个是说对temMsg赋值的所有的日志从新命名打印message
mutate {
        #重命名字段temMsg为message
        rename => {"temMsg" => "message"} 
}

3.过滤器切割

filter {                                      
    if [type] == "simple" {
        mutate{
                 split => ["message","|"]     #按 | 进行split切割message
                        add_field =>   {
                                "requestId" => "%{[message][0]}"
                        }
                        add_field =>   {
                                "timeCost" => "%{[message][1]}"
                        }
                        add_field =>   {
                                "responseStatus" => "%{[message][2]}"
                        }
                        add_field =>   {
                                "channelCode" => "%{[message][3]}"
                        }
                        add_field =>   {
                                "transCode" => "%{[message][4]}"
                        }
        }
        mutate {
            convert => ["timeCost", "integer"]  #修改timeCost字段类型为整型
        }
    } else if [type] == "detail" {
        grok{
            match => {             
                #将message里面 TJParam后面的内容，分隔并新增为ES字段和值
                "message" => ".*TJParam %{PROG:requestId} %{PROG:channelCode} %{PROG:transCode}"
            }
        }
        grok{
            match => { 
                #截取TJParam之前的字符作为temMsg字段的值
                "message" => "(?<temMsg>(.*)(?=TJParam)/?)" 
                #删除字段message
                remove_field => ["message"]          
            }
        }
        mutate {
             #重命名字段temMsg为message
            rename => {"temMsg" => "message"}           
        }
    }
}