一、环境

centos7
elastichsearch-6.2.2
node v8.11.3

二、nodejs的下载安装

其中，系统安装这里不讲了，elastichsearch-6.2.2安装教程在这里。

安装elasticsearch-head插件需要nodejs的支持，所以此处讲解一下安装nodejs步骤。

1.安装包下载

到nodejs官网现在最新nodejs，官网下载地址：https://nodejs.org/en/download/
这里写图片描述

当然，也可以直接使用命令下载：

[root@hadoop02 ~]# wget https://nodejs.org/dist/v8.11.3/node-v8.11.3-linux-x64.tar.xz

2.下载完成之后，进行解压安装：

这个文件是tar.xz文件，要分两步解压。

[root@hadoop02 node]# xz -d node-v8.11.3-linux-x64.tar.xz
...
[root@hadoop02 node]# tar -xvf  node-v8.11.3-linux-x64.tar
...

3.在/etc/profile中配置好path环境变量

[root@hadoop02 node]# vim /etc/profile

以自己安装的目录地址为准

export  PATH=${JAVA_HOME}/bin:$PATH:/opt/node/node-v8.11.3-linux-x64/bin

4.执行node -v验证安装

[root@hadoop02 node]# node -v
v8.11.3
[root@hadoop02 node]#

三、elastichsearch-head插件的下载安装

1.下载

地址：https://github.com/mobz/elasticsearch-head
它在git上面，要按照步骤来安装。
首先，安装git :yum install git
安装插件：clone elasticsearch-head: git clone https://github.com/mobz/elasticsearch-head.git

2.安装elastichsearch-head插件

进入elasticsearch-head目录下，执行npm install命令。
然后执行命令npm install [email protected] --ignore-scripts

3.启动elastichsearch-head

npm run start
验证elasticsearch-head,在浏览器中输入主机地址和端口(默认端口号是9100）如下图所示：

提示：请先启动elastichsearch再去验证。

四、可能出现的错误

安装过程中，网上有提到一些错误，但是我没有遇到，也有几个错误，我遇到了，网上没说，我在这里做个小总结；

1.执行命令npm install的时候，可能会报错，不要管，继续跑就行
2.启动elasticsearch的时候，可能会报错，这个是因为不能将elasticsearch-head放到plugins文件夹下

[a123@localhost bin]$ ./elasticsearch
Picked up _JAVA_OPTIONS: -Xms64m -Xmx64m -Xmn32m
Picked up _JAVA_OPTIONS: -Xms64m -Xmx64m -Xmn32m
Picked up _JAVA_OPTIONS: -Xms64m -Xmx64m -Xmn32m
[2018-03-31T20:25:19,776][WARN ][o.e.b.ElasticsearchUncaughtExceptionHandler] [] uncaught exception in thread [main]
org.elasticsearch.bootstrap.StartupException: java.lang.IllegalArgumentException: property [elasticsearch.version] is missing for plugin [head]
    at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:125) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:112) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124) ~[elasticsearch-cli-6.2.3.jar:6.2.3]
    at org.elasticsearch.cli.Command.main(Command.java:90) ~[elasticsearch-cli-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:85) ~[elasticsearch-6.2.3.jar:6.2.3]
Caused by: java.lang.IllegalArgumentException: property [elasticsearch.version] is missing for plugin [head]
    at org.elasticsearch.plugins.PluginInfo.readFromProperties(PluginInfo.java:226) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.plugins.PluginInfo.readFromProperties(PluginInfo.java:184) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Spawner.spawnNativePluginControllers(Spawner.java:75) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:167) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:323) ~[elasticsearch-6.2.3.jar:6.2.3]
    at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:121) ~[elasticsearch-6.2.3.jar:6.2.3]
    ... 6 more

修改elasticsearch配置即可，在elastichsearch.yml中添加如下命名即可：

#allow origin
http.cors.enabled: true
http.cors.allow-origin: "*"

PS:这个问题我没有遇到过，所以也没有加。
- 3.启动elasticsearch的时候，报错

[elasticsearch@hadoop02 elasticsearch-6.2.2]$ ./bin/elasticsearch
Exception in thread "main" 2018-07-30 21:41:53,588 main ERROR No log4j2 configuration file found. Using default configuration: logging only errors to the console. Set system property 'log4j2.debug' to show Log4j2 internal initialization logging.
SettingsException[Failed to load settings from [elasticsearch.yml]]; nested: JsonParseException[Duplicate field 'http.cors.enabled'
 at [Source: sun.nio.ch.ChannelInputStream@7c6908d7; line: 109, column: 19]];
        at org.elasticsearch.common.settings.Settings$Builder.loadFromStream(Settings.java:1187)
        at org.elasticsearch.common.settings.Settings$Builder.loadFromPath(Settings.java:1162)
        at org.elasticsearch.node.InternalSettingsPreparer.prepareEnvironment(InternalSettingsPreparer.java:99)
        at org.elasticsearch.cli.EnvironmentAwareCommand.createEnv(EnvironmentAwareCommand.java:95)
        at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86)
        at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124)
        at org.elasticsearch.cli.Command.main(Command.java:90)
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92)
        at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:85)
Caused by: com.fasterxml.jackson.core.JsonParseException: Duplicate field 'http.cors.enabled'
 at [Source: sun.nio.ch.ChannelInputStream@7c6908d7; line: 109, column: 19]
        at com.fasterxml.jackson.core.json.JsonReadContext._checkDup(JsonReadContext.java:204)
        at com.fasterxml.jackson.core.json.JsonReadContext.setCurrentName(JsonReadContext.java:198)
        at com.fasterxml.jackson.dataformat.yaml.YAMLParser.nextToken(YAMLParser.java:372)
        at org.elasticsearch.common.xcontent.json.JsonXContentParser.nextToken(JsonXContentParser.java:52)
        at org.elasticsearch.common.settings.Settings.fromXContent(Settings.java:698)
        at org.elasticsearch.common.settings.Settings.fromXContent(Settings.java:673)
        at org.elasticsearch.common.settings.Settings.access$500(Settings.java:82)
        at org.elasticsearch.common.settings.Settings$Builder.loadFromStream(Settings.java:1183)
        ... 8 more

网上有讲两个原因：首先可能是你的配置文件elasticsearch.yml格式可能有问题，比如冒号后面要有空格，前面不能有空格等；第二个就是没有log4j2的包，要去下载安装：

[root@node2 ~]# yum install -y log4j*    ###安装log4j包

在不断的尝试之后，多多测试，你也能供成功安装的~~

安装elasticsearch-head插件