ELK stack是什么?

ELK Stack 是 Elasticsearch、Logstash、Kibana 三个开源软件的组合。在实时数据检索和分析场合，三者通常是配合共用，而且又都先后归于 Elastic.co 公司名下，故有此简称。

ELK Stack 在最近两年迅速崛起，成为机器数据分析，或者说实时日志处理领域，开源界的第一选择。和传统的日志处理方案相比，ELK Stack 具有如下几个优点：

• 处理方式灵活。Elasticsearch 是实时全文索引，不需要像 storm 那样预先编程才能使用；
• 配置简易上手。Elasticsearch 全部采用 JSON 接口，Logstash 是 Ruby DSL 设计，都是目前业界最通用的配置语法设计；
• 检索性能高效。虽然每次查询都是实时计算，但是优秀的设计和实现基本可以达到全天数据查询的秒级响应；
• 集群线性扩展。不管是 Elasticsearch 集群还是 Logstash 集群都是可以线性扩展的；
• 前端操作炫丽。Kibana 界面上，只需要点击鼠标，就可以完成搜索、聚合功能，生成炫丽的仪表板。

以上摘自ELKstack中文指南


Logstash是能够用于收集,处理和转发事件或日志信息的工具.
Logstash : Logstash服务的组件，用于处理日志
Elasticsearch : 用于存储,索引日志
Kibana 4: 搜索和可视化的日志的Web界面.


Elasticsearch和Logstash需要运行Java环境,并且版本最好是1.7以上.
首先必须安装java7及以上的版本
http://www.java.com/zh_CN/download/linux_manual.jsp
[root@192_168_174_68 home]# wget 'http://sdlc-esd.oracle.com/ESD6/JSCDL/jdk/8u73-b02/jre-8u73-linux-x64.rpm?GroupName=JSC&FilePath=/ESD6/JSCDL/jdk/8u73-b02/jre-8u73-linux-x64.rpm&BHost=javadl.sun.com&File=jre-8u73-linux-x64.rpm&AuthParam=1457343423_73675d83c3aa00d667217e09e10d85c2&ext=.rpm' -O jre-8u73-linux-x64.rpm
--2016-03-07 17:18:01--  http://sdlc-esd.oracle.com/ESD6/JSCDL/jdk/8u73-b02/jre-8u73-linux-x64.rpm?GroupName=JSC&FilePath=/ESD6/JSCDL/jdk/8u73-b02/jre-8u73-linux-x64.rpm&BHost=javadl.sun.com&File=jre-8u73-linux-x64.rpm&AuthParam=1457343423_73675d83c3aa00d667217e09e10d85c2&ext=.rpm
Resolving sdlc-esd.oracle.com... 96.7.54.179, 96.7.54.187
Connecting to sdlc-esd.oracle.com|96.7.54.179|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 49210622 (47M) [application/x-sdlc]
Saving to: “jre-8u73-linux-x64.rpm”
100%[=================================================>] 49,210,622  1.58M/s   in 31s     
2016-03-07 17:18:32 (1.51 MB/s) - “jre-8u73-linux-x64.rpm” saved [49210622/49210622]
安装jdk

[root@192_168_174_68 home]# java -version
java version "1.8.0_73"
Java(TM) SE Runtime Environment (build 1.8.0_73-b02)
Java HotSpot(TM) 64-Bit Server VM (build 25.73-b02, mixed mode)

Elasticsearch 2.2.0安装

下载安装包.
[root@192_168_174_68 ~]# wget https://download.elastic.co/kibana/kibana/kibana-4.4.1-linux-x64.tar.gz
[root@192_168_174_68 ~]# tar zxvf kibana-4.4.1-linux-x64.tar.gz -C /opt/
[root@192_168_174_68 ~]# cd /opt/kibana-4.4.1-linux-x64/
修改配置文件
[root@192_168_174_68 kibana-4.4.1-linux-x64]# vim config/kibana.yml
server.port: 5601
server.host: "0.0.0.0"
elasticsearch.url: "http://192.168.174.68:9200"
启动服务
[root@192_168_174_68 kibana-4.4.1-linux-x64]# nohup ./bin/kibana -l /var/log/kibana4.4.1.log  &
[1] 8867
nohup: ignoring input and appending output to `nohup.out'



logstash安装

YUM源安装方式
下载安装公钥
rpm --import https://packages.elastic.co/GPG-KEY-elasticsearch
创建/etc/yum.repo.d/logstash.repo文件
[root@192_168_174_68 ~]# vim /etc/yum.repos.d/logstash.repo

[logstash-2.2]
name=Logstash repository for 2.2.x packages
baseurl=http://packages.elastic.co/logstash/2.2/centos
gpgcheck=1
gpgkey=http://packages.elastic.co/GPG-KEY-elasticsearch
enabled=1

[root@192_168_174_68 ~]# yum install logstash -y

测试:
[root@192_168_174_68 logstash]# JAVA_HOME=/usr/java/jre1.8.0_73 && /opt/logstash/bin/logstash  -e 'input { stdin { } } output { stdout {} }'     
Settings: Default pipeline workers: 8
Logstash startup completed
talen
2016-03-07T09:51:08.290Z 192_168_174_68 talen
测试OK
下面使用log4j模块收集日志
从Log4j SocketAppender通过TCP读取事件.只支持log4j 1.x版本.根据配置mode的不同,可以接受客户端连接也可以连接到服务端.根据mode不同,必需在对端配置SocketAppender或SocketHubAppender.
编辑业务的log4j配置,添加如下信息
log4j.rootLogger=logstash
log4j.appender.logstash=org.apache.log4j.net.SocketAppender
log4j.appender.logstash.port=56789
log4j.appender.logstash.remoteHost=192.168.174.68
修改logstash配置信息
[root@192_168_174_68 ~]# cat /etc/logstash/conf.d/3rd.conf
input {
        log4j {
                mode => "server"
                host  => "0.0.0.0"
                port => 56789
                type => "log4j"
        }
}
#The geoip plugin configuration requires data that is already defined as separate fields. Make sure that the geoip section is after the grok section of the configuration file.
output {
    elasticsearch {
        hosts =>  "192.168.174.68:9200"
    }
}
在浏览器中输入http://192.168.174.68:5601,可以看到收集上来的日志




问题一:

[root@192_168_174_68 ~]# service elasticsearch start 
Starting elasticsearch: Exception in thread "main" java.lang.IllegalStateException: Unable to access 'path.data' (/opt/elasticsearch.path.data/elasticsearch)
Likely root cause: java.nio.file.AccessDeniedException: /opt/elasticsearch.path.data/elasticsearch
        at sun.nio.fs.UnixException.translateToIOException(Unknown Source)
        at sun.nio.fs.UnixException.rethrowAsIOException(Unknown Source)
        at sun.nio.fs.UnixException.rethrowAsIOException(Unknown Source)
        at sun.nio.fs.UnixFileSystemProvider.createDirectory(Unknown Source)
        at java.nio.file.Files.createDirectory(Unknown Source)
        at java.nio.file.Files.createAndCheckIsDirectory(Unknown Source)
        at java.nio.file.Files.createDirectories(Unknown Source)
        at org.elasticsearch.bootstrap.Security.ensureDirectoryExists(Security.java:337)
        at org.elasticsearch.bootstrap.Security.addPath(Security.java:314)
        at org.elasticsearch.bootstrap.Security.addFilePermissions(Security.java:259)
        at org.elasticsearch.bootstrap.Security.createPermissions(Security.java:212)
        at org.elasticsearch.bootstrap.Security.configure(Security.java:118)
        at org.elasticsearch.bootstrap.Bootstrap.setupSecurity(Bootstrap.java:196)
        at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:167)
        at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:285)
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)
Refer to the log for complete error details.
                                                           [FAILED]
解决:

[root@192_168_174_68 opt]# chmod 777 /opt/elasticsearch.path.data/



参考:
https://www.elastic.co/guide/en/logstash/current/plugins-inputs-log4j.html
https://www.ttlsa.com/elk/howto-install-elasticsearch-logstash-and-kibana-elk-stack/