luaFilter组件：lua脚本过滤器。可以使用Lua脚本对msg、metadata、msgType进行过滤。根据脚本返回值路由到True或者False链。也可以启动加载lua第三方库，进行例如：加解密、I/O、网络、文件等高级操作。

Lua脚本使用加解密、I/O、网络、文件等高级操作库，需要通过以下配置开启：config.Properties.PutValue(luaEngine.LoadLuaLibs, "true")

Lua脚本支持Lua5.1语法规范，请参考gopher-lua (opens new window) 。

配置

字段	类型	说明	默认值
script	string	lua脚本，或者与.lua后缀的lua脚本文件路径	无

• script：可以对msg、metadata、msgType进行过滤。只需要提供函数体内容，如果是文件路径，则需要提供完整的脚本函数：

      function Filter(msg, metadata, msgType) 
          ${script} 
       end
  

  • msg：消息内容，如果dataType=JSON，可以使用msg.temperature 方式操作。如果dataType是其他类型，该字段类型是:string
  • metadata：消息元数据，类型：jsonObject
  • msgType：消息类型
  • 函数返回值类型：boolean，决定和下一个节点的连接关系（Relation Type）

Relation Type

• True: 把消息发送到True链
• False: 把消息发送到False链
• Failure: 执行失败，把消息发送到Failure链

执行结果

该组件不会改变msg、metadata和msgType内容。

配置示例

  {
    "id": "s1",
    "type": "x/luaFilter",
    "name": "过滤",
    "configuration": {
      "script": "return msg.temperature > 50"
    }
  }

自定义函数

可以通过config.RegisterUdf注册golang函数，然后在Lua脚本中使用，其注册方式和用法和Js一致。详情参考Udf 。

加载Lua模块

可以通过加载Lua自定义或者第三方模块库，扩展Lua能力，使用以下方式把Lua模块注册到引擎中：

import luaEngine "github.com/rulego/rulego-components/pkg/lua_engine"

luaEngine.Preloader.Register(func(state *lua.LState) {
	//加载模块
	//libs.Preload(state)
})

使用Golang实现Lua模块参考 (opens new window)

另外框架内置了大量的Lua第三方库模块，使用以下方式启用，默认不加载：

config.Properties.PutValue(luaEngine.LoadLuaLibs, "true")

启动后可以进行加解密、I/O、网络、数据库、文件等高级操作，第三方库列表：

• argparse (opens new window) argparse CLI parsing https://github.com/luarocks/argparse (opens new window)
• base64 (opens new window) encoding/base64 (opens new window) api
• cloudwatch (opens new window) aws cloudwatch log access
• cert_util (opens new window) monitoring ssl certs
• chef (opens new window) chef client api
• cmd (opens new window) cmd port
• crypto (opens new window) calculate md5, sha256 hash for string
• db (opens new window) access to databases
• filepath (opens new window) path.filepath port
• goos (opens new window) os port
• http (opens new window) http.client && http.server
• humanize (opens new window) humanize github.com/dustin/go-humanize (opens new window) port
• inspect (opens new window) pretty print github.com/kikito/inspect.lua (opens new window)
• ioutil (opens new window) io/ioutil port
• json (opens new window) json implementation
• log (opens new window) log port
• plugin (opens new window) run lua code in lua code
• pprof (opens new window) pprof http-server for golang from lua
• prometheus (opens new window) prometheus exporter
• regexp (opens new window) regexp port
• runtime runtime port
• pb (opens new window) https://github.com/cheggaaa/pb (opens new window) port (v3)
• shellescape (opens new window) shellescape https://github.com/alessio/shellescape (opens new window) port
• stats (opens new window) stats https://github.com/montanaflynn/stats (opens new window) port
• storage (opens new window) package for store persist data and share values between lua states
• strings (opens new window) strings port (utf supported)
• tac (opens new window) tac line-by-line scanner (from end of file to up)
• tcp (opens new window) raw tcp client lib
• telegram (opens new window) telegram bot
• template (opens new window) template engines
• time (opens new window) time port
• xmlpath (opens new window) gopkg.in/xmlpath.v2 (opens new window) port
• yaml (opens new window) gopkg.in/yaml.v2 (opens new window) port
• zabbix (opens new window) zabbix bot