There definitely should be a way to adjust options to --apply-logs. However, I don't think it makes sense to pass the same "additional-options" unconditionally to both the innobackupex backup and apply-logs phases.
And that can be customized as needed. This allows adjusting the command to use --apply-logs-only and/or adding any set of other parameters some of which may not be easily anticipated today.
There definitely should be a way to adjust options to --apply-logs. However, I don't think it makes sense to pass the same "additional- options" unconditionally to both the innobackupex backup and apply-logs phases.
Perhaps we should just have, as a default:
prepare-command = "innobackupex --apply-logs ${target_ directory} "
And that can be customized as needed. This allows adjusting the command to use --apply-logs-only and/or adding any set of other parameters some of which may not be easily anticipated today.