在logstash的 filter 中 嵌套型json 用 grok 、或者ruby 应该怎么写？

 2018-02-25 16:18:42[ INFO ]{"behaviouralAnalysisDataEntityList":[{"btnNameList":["bet1","ben2"],"enterDivMsgEntity":[{"divClass":"DIVclass","divContent":"divContent","divTitle":"divTitle","enterTime":"Sun Feb 25 16:18:42 CST 2018"}],"webmoduleName":"考评","webmoduleNameAndWebPageName":"武","webpageName":"文件管理"}],"broserCookieEnabled":true,"broserLanguage":"en-ch","broserPlatform":"win32","browserDomain":"域名","browserHeight":"200","browserName":"谷歌","browserReferrer":"http://localhost:4200","browserWidth":"100","userId":"mjx","userName":"mjxName"}
这个 用grok 或者ruby 应该怎么写，给个思路也好