Logstash 入门实战(4)--filter plugin 介绍(logstash gsub)

本文主要介绍 Logstash 的一些常用过滤插件；相关的环境及软件信息如下：CentOS 7.9、Logstash 8.2.2。 1、grok 过滤插件 grok 是一种将行与正则表达式匹配，将行的特定部分映射到专用字段中以及根据此映射执行操作的方法。Logstash 中内置了超过 200 种 L ...

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本文主要介绍 Logstash 的一些常用过滤插件；相关的环境及软件信息如下：CentOS7.9、Logstash 8.2.2。

1、grok 过滤插件

grok 是一种将行与正则表达式匹配，将行的特定部分映射到专用字段中以及根据此映射执行操作的方法。Logstash 中内置了超过 200 种Logstash 模式，用于过滤单词、数字和日期等。 如果找不到所需的模式，可以自定义模式。 还有多个匹配模式的选项，可简化表达式的编写以捕获日志数据。

Logstash grok 过滤插件的基本语法格式：

%{PATTERN:FieldName}

grok 可以非结构化的数据转变为结构化数据，非常适用于各类系统日志；下面使用Grok 来处理 Nginx访问日志。

一行 Nginx 访问日志：

10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] "GET /favicon.ico HTTP/1.1" 404 555 "http://10.49.196.11:8066/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36"

配置 Logstash：

input { stdin { }}filter { grok { match => { "message" => "%{IP:ip} - %{USER:remoteUser} \[%{HTTPDATE:accessTimeStr}\] \"%{WORD:method} %{URIPATHPARAM:path} %{WORD:protocal}/%{NUMBER:version}\" %{INT:status} %{INT:bytes} \"%{DATA:referer}\" \"%{DATA:userAgent}\""} }}output { stdout { }}

运行 Logstash 后输入日志信息：

10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] "GET /favicon.ico HTTP/1.1" 404 555 "http://10.49.196.11:8066/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36"{ "method" => "GET", "host" => { "hostname" => "pxc2" }, "accessTimeStr" => "27/Sep/2022:10:16:15 +0800", "userAgent" => "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36", "referer" => "http://10.49.196.11:8066/", "ip" => "10.49.196.1", "message" => "10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] \"GET /favicon.ico HTTP/1.1\" 404 555 \"http://10.49.196.11:8066/\" \"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36\"", "@timestamp" => 2022-09-27T02:31:13.852428Z, "bytes" => "555", "remoteUser" => "-", "@version" => "1", "event" => { "original" => "10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] \"GET /favicon.ico HTTP/1.1\" 404 555 \"http://10.49.196.11:8066/\" \"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36\"" }, "path" => "/favicon.ico", "status" => "404", "version" => "1.1", "protocal" => "HTTP"}

可以看到各字段信息都解析出来了。

各正则表达式定义的详细信息，可以参考https://github.com/logstash-plugins/logstash-patterns-core/tree/main/patterns，如：

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})2、dissect 过滤插件

基于分隔符原理解析数据，解决grok解析时消耗过多cpu资源的问题。使用分隔符将非结构化事件数据提取到字段中。 解剖过滤器不使用正则表达式，速度非常快。 但是，如果数据的结构因行而异，grok 过滤器更合适。dissect 的应用有一定的局限性：主要适用于每行格式相似且分隔符明确简单的场景。

dissect 语法比较简单，有一系列字段(field)和分隔符(delimiter)组成

%{}字段%{}之间是分隔符

使用 Dissect 处理 Nginx 访问日志：

input { stdin { }}filter { dissect { mapping => { "message" => '%{ip} - %{remoteUser} [%{accessTimeStr} %{+accessTimeStr}] "%{method} %{path} %{protocal}/%{version}" %{status} %{bytes} "%{referer}" "%{userAgent}"'} }}output { stdout { }}

结果如下，与使用 grok 处理 Nginx 访问日志的结果一致：

10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] "GET /favicon.ico HTTP/1.1" 404 555 "http://10.49.196.11:8066/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36"{ "path" => "/favicon.ico", "status" => "404", "protocal" => "HTTP", "host" => { "hostname" => "pxc2" }, "bytes" => "555", "userAgent" => "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36", "@version" => "1", "event" => { "original" => "10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] \"GET /favicon.ico HTTP/1.1\" 404 555 \"http://10.49.196.11:8066/\" \"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36\"" }, "referer" => "http://10.49.196.11:8066/", "accessTimeStr" => "27/Sep/2022:10:16:15 +0800", "message" => "10.49.196.1 - - [27/Sep/2022:10:16:15 +0800] \"GET /favicon.ico HTTP/1.1\" 404 555 \"http://10.49.196.11:8066/\" \"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36\"", "method" => "GET", "version" => "1.1", "@timestamp" => 2022-09-27T09:28:36.042881Z, "remoteUser" => "-", "ip" => "10.49.196.1"}

dissect 除了字段外面的字符串定位功能以外，还通过几个特殊符号来处理字段提取的规则：

%{+key}+代表该匹配值追加到 key 字段下%{ts} %{+ts} %{+ts}Apr 26 12:20:02{ "ts":"Apr 26 12:20:02"}%{+key/2}后面的数字代表拼接的次序%{+order/2} %{+order/3} %{+order/1} %{+order/4}two three one go{ "order": "one two three go"}%{} 表示一个空的跳过字段%{a} %{} %{b}1 2 3{"a":"1","b":"3"}%{?key} ?表示，这块只是一个占位，并不会实际生成捕获字段存到事件里面。%{?key} %{&key}当同样捕获名称都是string，但是一个?一个&的时候，表示这是一个键值对。%{?key1}=%{&key1}&%{?key2}=%{&key2}a=1&b=2{"a":"1","b":"2"}%{key->}，表示忽略它右边的填充，否则右边的多余填充将拆分到下一个字段中。%{a} %{b->} %{c}1 2 3{"a":"1","b":"2","c":"3"}#去除->后，会把多余的空格匹配到 c 中%{a} %{b} %{c}1 2 3{"a":"1","b":"2","c":" 3"}3、date 过滤插件

date 过滤插件可以把字符串的日期字段转为日期类型。

input { stdin { codec => "json" }}filter { date { match => ["accessTimeStr", "dd/MMM/yyyy:HH:mm:ss Z"] target => "accessTime" }}output { stdout { }}

上述配置把 accessTimeStr 字段的值转成日期类型，并写入accessTime 字段(默认为 @timestamp 字段)。运行 Logstash：

{"accessTimeStr": "27/Sep/2022:10:16:15 +0800"}{ "event" => { "original" => "{\"accessTimeStr\": \"27/Sep/2022:10:16:15 +0800\"}\n" }, "host" => { "hostname" => "pxc2" }, "@timestamp" => 2022-09-27T07:21:00.181981Z, "accessTime" => 2022-09-27T02:16:15Z, "@version" => "1", "accessTimeStr" => "27/Sep/2022:10:16:15 +0800"}4、mutate 过滤插件

mutate 插件可以对字段进行重命名、删除、替换、更新等操作：

convert 类型转换gsub 字符串替换split 字符串分割join 数组合转为字符串merge 数组合并为数组rename 字段重命名update 字段内容更新，如果字段不存在，则不处理replace 字段内容替换，如果字段不存在，则新增字段input { stdin { codec => "json" }}filter { mutate { convert => {"a" => "integer"} gsub => ["b", "_", "|"] #"_"替换为"|" split => {"c" => ","} join => {"d" => ","} merge => {"e1" => "e2"} #数组e2的元素合并到e1数组中 rename => {"f" => "ff"} update => {"g" => "new value"} replace => {"h" => "new value"} }}output { stdout { }}

启动 Logstash 并在控制输入测试数据：

{"a":"1","b":"A_B_C","c":"X,Y,Z","d":[1,2,3],"e1":[1,2,3],"e2":[4,5,6],"f":"ABC","g":"123"}{ "d" => "1,2,3", "e1" => [ [0] 1, [1] 2, [2] 3, [3] 4, [4] 5, [5] 6 ], "e2" => [ [0] 4, [1] 5, [2] 6 ], "c" => [ [0] "X", [1] "Y", [2] "Z" ], "event" => { "original" => "{\"a\":\"1\",\"b\":\"A_B_C\",\"c\":\"X,Y,Z\",\"d\":[1,2,3],\"e1\":[1,2,3],\"e2\":[4,5,6],\"f\":\"ABC\",\"g\":\"123\"}\n" }, "ff" => "ABC", "@timestamp" => 2022-09-28T02:45:26.305729Z, "b" => "A|B|C", "@version" => "1", "host" => { "hostname" => "pxc2" }, "h" => "new value", "g" => "new value", "a" => 1}5、json 过滤插件

json 插件可以把内容为 json 字符串的字段转换为 json 格式数据。

input { stdin { }}filter { json { source => "message" target => "result" }}output { stdout { }}

启动 Logstash 并在控制输入测试数据：

{"a":"1","b":"2"}{ "message" => "{\"a\":\"1\",\"b\":\"2\"}", "event" => { "original" => "{\"a\":\"1\",\"b\":\"2\"}" }, "@version" => "1", "@timestamp" => 2022-09-28T03:20:35.827102Z, "result" => { "b" => "2", "a" => "1" }, "host" => { "hostname" => "pxc2" }}6、ruby 过滤插件

ruby 插件时最灵活的插件，可以使用 ruby 来随心所欲的修改 Logstash Event 对象。

input { stdin { codec = "json" }}filter { ruby { code => 'a = event.get("a");event.set("a", a + 123")' }}output { stdout { }}

启动 Logstash 并在控制输入测试数据：

{"a":"1","b":"2"}{ "host" => { "hostname" => "pxc2" }, "b" => "2", "a" => "1abc", "@version" => "1", "event" => { "original" => "{\"a\":\"1\",\"b\":\"2\"}\n" }, "@timestamp" => 2022-09-28T06:01:35.180939Z}

本文中介绍的插件只是 Logstash 输入插件的很小的一部分，可查看Logstash 官方文档了解更多信息。