[doc] hertzbeat plugin doc. (apache#1980)

Author: zqr10159

home/docs/help/guide.md

@@ -131,3 +131,7 @@ More details see&emsp;&#x1F449;&emsp;[Threshold alarm](alert_threshold) <br />
 &emsp;&#x1F449;&emsp;[Configure DingDing Robot Notification](alert_dingtalk) <br />
 &emsp;&#x1F449;&emsp;[Configure FeiShu Robot Notification](alert_feishu) <br />
 &emsp;&#x1F449;&emsp;[Configure Huawei Cloud SMN Notification](alert_smn) <br />
+
+### Plugins
+
+&emsp;&#x1F449;&emsp;[Plugin](plugin) <br />

home/docs/help/issue.md

@@ -22,12 +22,12 @@ The hertzbeat installed and deployed by the installation package is not availabl
 ### Docker Deployment common issues   
 
 1. **MYSQL, TDENGINE and HertzBeat are deployed on the same host by Docker,HertzBeat use localhost or 127.0.0.1 connect to the database but fail**     
-The problems lies in Docker container failed to visit and connect localhost port. Beacuse the docker default network mode is Bridge mode which can't access loacl machine through localhost.
+The problems lies in Docker container failed to visit and connect localhost port. Because the docker default network mode is Bridge mode which can't access local machine through localhost.
 > Solution A：Configure application.yml. Change database connection address from localhost to external IP of the host machine.     
 > Solution B：Use the Host network mode to start Docker, namely making Docker container and hosting share network. `docker run -d --network host .....`    
 
 2. **According to the process deploy，visit http://ip:1157/ no interface**   
-Please refer to the following points to troubleshoot issuess：  
+Please refer to the following points to troubleshoot issues：  
 > one：Whether the MySQL database and tdengine database as dependent services have been successfully started, whether the corresponding hertzbeat database has been created, and whether the SQL script has been executed.    
 > two：Check whether dependent service, IP account and password configuration is correct in HertzBeat's configuration file `application.yml`.  
 > > three：`docker logs hertzbeat` Check whether the container log has errors. If you haven't solved the issue, report it to the communication group or community.
@@ -39,7 +39,7 @@ Please refer to the following points to troubleshoot issuess：
 ### Package Deployment common issues
 
 1. **According to the process deploy，visit http://ip:1157/ no interface**   
-   Please refer to the following points to troubleshoot issuess:
+   Please refer to the following points to troubleshoot issues:
 > one：Whether the MySQL database and tdengine database as dependent services have been successfully started, whether the corresponding hertzbeat database has been created, and whether the SQL script has been executed.    
 > two：Check whether dependent services, IP account and password configuration is correct in HertzBeat's configuration file `hertzbeat/config/application.yml`.    
 > three： Check whether the running log has errors in `hertzbeat/logs/` directory. If you haven't solved the issue, report it to the communication group or community.

home/docs/help/plugin.md

@@ -0,0 +1,25 @@
+---
+id: plugin  
+title: Custom plugin      
+sidebar_label: Custom plugin 
+---
+
+## Custom plugins
+### Introduction
+
+Currently, `Hertzbeat` relies on the `alert` module to notify the user, and then the user can take actions such as sending requests, executing `sql`, executing `shell` scripts, etc. However, this can only be automated manually or by `webhook` to receive the alert message.
+However, at present, it is only possible to automate the process by receiving alert messages manually or through a `webhook`. For this reason, `HertzBeat` has added a new `plugin` module, which has a generic interface `Plugin`, which allows users to implement the `alert` method of this interface and receive the `Alert` class as a parameter to customize the operation.
+After adding the customized code, you only need to package the `plugin` module, copy it to the `/ext-lib` folder under the installation directory, restart the `HertzBeat` main program, and then you can execute the customized function after the alert, without having to re-package and deploy the whole program by yourself.
+Currently, `HertzBeat` only set up the trigger `alert` method after alarm, if you need to set up the trigger method at the time of acquisition, startup program, etc., please mention `Task` in `https://github.com/apache/hertzbeat/issues/new/choose`.
+
+### Specific uses
+1. Pull the master branch code `git clone https://github.com/apache/hertzbeat.git` and locate the `plugin` module's
+   `Plugin` interface.
+   ![plugin-1.png](home/static/img/docs/help/plugin-1.png)
+2. In the `org.apache.hertzbeat.plugin.impl` directory, create a new interface implementation class, such as `org.apache.hertzbeat.plugin.impl.DemoPluginImpl`, and receive the `Alert` class as a parameter, implement the `alert ` method, the logic is customized by the user, here we simply print the object.
+   ![plugin-2.png](home/static/img/docs/help/plugin-2.png)
+3. Package the `hertzbeat-plugin` module.
+   ![plugin-3.png](home/static/img/docs/help/plugin-3.png)
+4. Copy the packaged `jar` package to the `ext-lib` directory under the installation directory (for `docker` installations, mount the `ext-lib` directory first, then copy it there).
+   ![plugin-4.png](home/static/img/docs/help/plugin-4.png)
+5. Then restart `HertzBeat` to enable the customized post-alert handling policy.

home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/guide.md

@@ -130,3 +130,7 @@ sidebar_label: 帮助入门
 &emsp;&#x1F449;&emsp;[配置钉钉机器人通知](alert_dingtalk) <br />
 &emsp;&#x1F449;&emsp;[配置飞书机器人通知](alert_feishu) <br />
 &emsp;&#x1F449;&emsp;[配置华为云SMN通知](alert_smn) <br />
+
+### 插件
+
+&emsp;&#x1F449;&emsp;[插件](plugin) <br />

home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/plugin.md

@@ -0,0 +1,25 @@
+---
+id: plugin  
+title: 自定义插件      
+sidebar_label: 自定义插件 
+---
+
+## 自定义插件
+### 简介
+
+当前`Hertzbeat`在使用时，主要依赖`alert`模块对用户进行通知，然后用户采取一些措施如发送请求、执行`sql`、执行`shell`脚本等。
+但目前只能通过手动或者`webhook`接收告警信息进行自动化处理。基于此，`HertzBeat`新增了`plugin`模块，该模块有一个通用接口`Plugin`，用户可以自己实现这个接口的`alert`方法，接收`Alert`类作为参数进行自定义操作。
+用户添加自定义代码后，只需要对`plugin`模块进行打包，拷贝到安装目录下`/ext-lib`文件夹中，重启`HertzBeat`主程序，即可实现告警后执行自定义功能，无需自己重新打包部署整个程序。
+目前，`HertzBeat`只在告警后设置了触发`alert`方法，如需在采集、启动程序等时机设置触发方法，请在`https://github.com/apache/hertzbeat/issues/new/choose` 提`Task`。
+
+### 具体使用
+1. 拉取主分支代码 `git clone https://github.com/apache/hertzbeat.git` ，定位到`plugin`模块的
+   `Plugin`接口。
+    ![plugin-1.png](home/static/img/docs/help/plugin-1.png)
+2. 在`org.apache.hertzbeat.plugin.impl`目录下, 新建一个接口实现类，如`org.apache.hertzbeat.plugin.impl.DemoPluginImpl`,在实现类中接收`Alert`类作为参数，实现`alert`方法，逻辑由用户自定义，这里我们简单打印一下对象。
+    ![plugin-2.png](home/static/img/docs/help/plugin-2.png)
+3. 打包`hertzbeat-plugin`模块。
+    ![plugin-3.png](home/static/img/docs/help/plugin-3.png)
+4. 将打包后的`jar`包，拷贝到安装目录下的`ext-lib`目录下（若为`docker`安装则先将`ext-lib`目录挂载出来，再拷贝到该目录下）
+    ![plugin-4.png](home/static/img/docs/help/plugin-4.png)
+5. 然后重启`HertzBeat`，即可实现自定义告警后处理策略。

home/sidebars.json

@@ -309,7 +309,8 @@
             "help/alert_smn"
           ]
         },
-        "help/issue"
+        "help/issue",
+        "help/plugin"
       ]
     },
     {