Amazon ElastiCache for Redis now supports auto scaling in the AWS GovCloud (US-West) and AWS GovCloud (US-East) Regions. With auto scaling, ElastiCache for Redis automatically adjusts capacity to maintain steady, predictable performance at the lowest possible cost. You can automatically scale your cluster horizontally by adding or removing shards or replica nodes. ElastiCache for Redis uses AWS Application Auto Scaling to manage scaling and Amazon CloudWatch metrics to determine when it is time to scale up or down.
Source:: Amazon AWS