AFAIK (but I may be wrong here so if anyone knows better please feel free to correct me) the AWS cluster implementation is a single master and multiple read sla

AFAIK (but I may be wrong here so if anyone knows better please feel free to correct me) the AWS cluster implementation is a single master and multiple read slaves. Failover is done manually with an API call and in an event of the master's failure, EC spins up a new (empty) master automatically before you can promote a slave in its place.