Redis with ElastiCache
We configure and create a managed ElastiCache Redis instance. In this case, we also have a replica node (acting as a read-only node if we wanted to use it). We select the Multi-AZ option, which tells aws to use the Read Replica as a fallback (to be promoted to master) if needed.
ElastiCache for Redis has more complicated configurations than we cover here. You can read about clusters and sharing (along with other details) in the docs here.