Is snapshot_retention_limit enforced for NIST SP 800-53 Rev 5?

Yes, When automatic backups are enabled, AWS ElastiCache creates a backup of the cluster on a daily basis. The backup can be retained for a number of days as specified by your organization. Automatic backups can help guard against data loss.

terraform-aws-modules/elasticache/aws for NIST SP 800-53 Rev 5

Controls

4 controls from NIST SP 800-53 Rev 5 apply to this module.

Control	Clause	Change
CloudWatch log groups should have retention period of at least 365 dayscloudwatch_log_group_retention_period_365 AC-16(b)	AC-16(b)
ElastiCache Redis clusters should have automatic backups enabled with a retention period of 15 days or greaterelasticache_redis_cluster_automatic_backup_retention_15_days None	None
Log groups should have encryption at rest enabledlog_group_encryption_at_rest_enabled AU-9(3)	AU-9(3)
VPC Security groups should only allow unrestricted incoming traffic for authorized portsvpc_security_group_allows_ingress_authorized_ports SC-7	SC-7