ElastiCache clusters should have automatic minor version upgrades enabled

How to fix it

Enable automatic minor version upgrades on the cache cluster the finding names. AWS honours the setting only on Redis OSS 6.0 and later; on an older engine the parameter is ignored and the finding will not clear until the engine version itself is raised first. An upgrade, when one is eventually applied, lands in the maintenance window and replaces nodes, so a cluster with a replica fails over and a single node cluster is briefly unavailable and starts cold.

In the console

ElastiCache → the cache → Modify → Maintenance → Auto upgrade minor versions

With the AWS CLI

aws elasticache modify-cache-cluster --cache-cluster-id <cache-cluster-id> --auto-minor-version-upgrade --region <region>

With Terraform

resource "aws_elasticache_cluster" "this" {
  cluster_id                 = var.cluster_id
  engine                     = "redis"
  auto_minor_version_upgrade = true
}