Neptune DB clusters should have IAM database authentication enabled

How to fix it

• Can break clients: Once it is on, every request must be signed with AWS Signature Version 4, so move each client to signed requests first or it is refused.
• Interrupts service: Turning it on restarts the DB engine, which ends every open connection to the cluster and briefly interrupts availability.
• Affects another check: RDS.12 reads the same setting on this cluster, so turning it on here clears that finding too.

In the console

Neptune → Databases → the DB cluster → Actions → Modify → Additional settings

IAM DB Authentication

Turn on IAM Authentication

Scheduling of modifications

Apply immediately at a quiet time, or wait for the next maintenance window

With the AWS CLI

aws neptune modify-db-cluster --db-cluster-identifier <db-cluster-identifier> --enable-iam-database-authentication --apply-immediately --region <region>

With Terraform

resource "aws_neptune_cluster" "this" {
  cluster_identifier                  = var.cluster_identifier
  iam_database_authentication_enabled = true
}