Adding autoscaling policy for redis with terraform

Question

I am trying to set the autoscaling policy for redis via terraform.

I am setting the autoscaling policy as follows:

# Attach the autoscaling policy to the Redis replication group
resource "aws_appautoscaling_target" "redis_autoscaling_target" {
  max_capacity       = 10
  min_capacity       = 1
  resource_id        = "elasticache:${module.elasticache_redis.elasticache_replication_group_id}"
  scalable_dimension = "elasticache:replication-group:NodeGroups"
  service_namespace  = "elasticache"
}

The module to setup redis in cluster mode is as follows:

module "elasticache_redis" {
  source = "umotif-public/elasticache-redis/aws"
  version = "~> 3.0.0"
    
  name_prefix           = "${var.redis_cache_name}-${var.environment}"
  num_cache_clusters    = var.redis_number_cache_clusters
  node_type             = var.redis_node_type
    
  cluster_mode_enabled    = true
  replicas_per_node_group = 1
  num_node_groups         = 2
    
  //rest of config is not important
}

I keep getting the following error:

creating Application AutoScaling Target (elasticache:test-redis): ValidationException: Unsupported service namespace, resource type or scalable dimension

Answer 1

The format of the resource id was incorrect. From example below the format should be replication-group/mycluster where you replace mycluster with the cluster id which is ${module.elasticache_redis.elasticache_replication_group_id} in my case.

aws application-autoscaling register-scalable-target \
   --service-namespace elasticache \
   --scalable-dimension elasticache:replication-group:NodeGroups \
   --resource-id replication-group/mycluster \
   --min-capacity 1 \
   --max-capacity 5

Reference: https://docs.aws.amazon.com/autoscaling/application/userguide/services-that-can-integrate-elasticache.html