AddFlags adds flags.

ExecuteAction execute the action returned by the createAction function.

RolloverIndices return an array of indices to rollover.

ActionExecuteOptions are the options passed to the execute action function.

Config holds the global configurations for the es rollover, common to all actions.

IndexOption holds the information for the indices to rollover.

Action is an interface that each action (init, rollover and lookback) of the es-rollover should implement.

ActionCreatorFunction type is the function type in charge of create the action to be executed.