AWS::ElastiCache::ReplicationGroup EngineVersion

The version number of the cache engine to be used for the clusters in this replication group. To view the supported cache engine versions, use the DescribeCacheEngineVersions operation.

こんな感じで出してみる

aws --region ap-northeast-1 elasticache describe-cache-engine-versions --engine redis

EngineVersionとCacheParameterGroupFamilyが必要

        {
            "Engine": "redis",
            "EngineVersion": "7.1",
            "CacheParameterGroupFamily": "redis7",
            "CacheEngineDescription": "Redis",
            "CacheEngineVersionDescription": "redis version 7.1.0"
        }

docs.aws.amazon.com