All checks
Medium ElastiCache · regional

ElastiCache replication groups should have automatic failover enabled

Checks that ElastiCache (Redis OSS or Valkey) replication groups have automatic failover enabled, so a read replica is promoted when the primary fails and writes resume within seconds instead of waiting for a new primary. A group whose only node is its primary must add a read replica before failover can be enabled.

service
ElastiCache
severity
Medium
scope
evaluated in every region

How to fix it

In the console

ElastiCache → Valkey caches or Redis OSS caches → the cache → Actions → Modify

Auto failover
Enable
Multi-AZ
Enable, recommended, so the replica it fails over to is in another Availability Zone

With the AWS CLI

  • Interrupts service: --apply-immediately also applies any pending change to the group now, such as a node type or engine version change, which can replace nodes.
aws elasticache modify-replication-group --replication-group-id <replication-group-id> --automatic-failover-enabled --apply-immediately --region <region>

With Terraform

resource "aws_elasticache_replication_group" "this" {
  replication_group_id       = var.replication_group_id
  description                = var.description
  num_cache_clusters         = var.num_cache_clusters
  automatic_failover_enabled = true
}

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