BindRolloverIndices bind the task to rollover indices.

FilterReadyToBeDeleteIndices filter indices that is ready to be deleted.

FilterToBeDeleteIndicies return the indices that need be delete.

GetAliasURL return the ES alisese endpoint.

IsIdxIsWriteAlias check is indices' alias is write-alias.

IsIdxShouldDelete check whether a index is should tobe deleted dateStr like `2016.10.31`, treated as +0800.

LoadAliases load all indices aliases from ES.

LoadAllIndicesNames load all indices name by ES API.

LoadSettings load task settings.

RemoveIndexByName delete index by elasticsearch RESTful API.

RunDeleteTask start to delete indices.

AliasesResp is the response of es aliases API.

IdxSetting is the task settings.