Elasticsearch更新license:
初次安装Marvel,有30天的使用时间，当到期后，只保存7天的数据，所以需要注册申请一个license:
注册申请地址：
https://register.elastic.co/marvel_register
注册后的license会以邮箱的形式进行反馈：
Ps:lincese有效期为一年
查看elasticsearch的版本：
下载相应的lincese版本,上传至服务器：
1.curl -XPUT ‘http://10.26.44.42:9200/_license’ -d @license.json
返回：
{"acknowledged":false,"license_status":"valid","acknowledge":{"message":"This license update requires acknowledgement. To acknowledge the license, please read the following messages and update the license again, this time with the "acknowledge=true" parameter:","marvel":["basic","Automatic index cleanup is locked to 7 days for clusters with [{}] license.basic"]}}
2.curl -XPUT ‘http://10.26.44.42:9200/_licenses?acknowledge=true’ -d @license.json
返回：
{"acknowledged":true,"license_status":"valid"}
3.curl -XGET -u user:password ‘http://10.26.44.42:9200/_license’
参考文档：
Elasticsearch2.x:
https://www.elastic.co/guide/en/marvel/current/license-management.html
Elasticsearch5.x:
https://www.elastic.co/guide/en/x-pack/current/installing-license.html