AWS Elasticache Terraform module

Terraform module which creates Elasticache clusters within existing VPC on AWS.

A choice of two types of elasticache backends are supported:

• Memcached
• Redis

The following objects are created by the module:

• aws_elasticache_parameter_group
• aws_elasticache_cluster
• aws_elasticache_replication_group
• aws_security_group
• aws_security_group_rule
• aws_route53_record

Terraform versions

Terraform 0.12. Pin module version to ~> v2.0. Submit pull-requests to master branch.

Terraform 0.11. Pin module version to ~> v1.0. Submit pull-requests to terraform011 branch.

Usage

To create a Memcached cluster:

module "memcached-nonprod" {
  source                    = "github.com/InnovateUKGitHub/terraform-module-elasticache"
  enable_elasticache        = var.enable_elasticache_nonprod
  deploy_env                = var.deploy_env
  vpc_id                    = data.terraform_remote_state.vpc.vpc_id
  local_dns_domain_zone_id  = aws_route53_zone.local_private.zone_id
  elasticache_clients_sgs   = [aws_security_group.openshift-compute-node.id, aws_security_group.bastion.id]
  subnet_group_name         = data.terraform_remote_state.vpc.elasticache_subnet_group_name
  purpose                   = "nonprod"
  elasticache_multi_az      = true
  notification_topic_arn    = aws_sns_topic.ElastiCache-Events.arn
  elasticache_instance_type = var.elasticache_nonprod_instance_size
  elasticache_family        = "memcached1.4"
  num_elasticache_instances = 2
}

output "elasticache_memcached_nonprod_cluster_address" {
  value = module.memcached-nonprod.cluster_address
}

output "elasticache_memcached_nonprod_cluster_alias" {
  value = module.memcached-nonprod.cluster_alias
}

To create a Redis cluster:

module "redis-nonprod" {
  source                     = "github.com/InnovateUKGitHub/terraform-module-elasticache"
  enable_elasticache         = var.enable_elasticache_nonprod
  deploy_env                 = var.deploy_env
  vpc_id                     = data.terraform_remote_state.vpc.vpc_id
  local_dns_domain_zone_id   = aws_route53_zone.local_private.zone_id
  elasticache_clients_sgs    = [aws_security_group.openshift-compute-node.id, aws_security_group.bastion.id]
  elasticache_family         = "redis5.0"
  elasticache_engine         = "redis"
  elasticache_engine_version = "5.0.5"
  subnet_group_name          = data.terraform_remote_state.vpc.elasticache_subnet_group_name
  purpose                    = "nonprod-redis"
  elasticache_multi_az       = false
  notification_topic_arn     = aws_sns_topic.ElastiCache-Events.arn
  elasticache_instance_type  = var.elasticache_prod_instance_size
  num_elasticache_instances  = 2
  elasticache_password       = "Password for the service goes here?"
}

output "elasticache_redis_nonprod_cluster_address" {
  value = module.redis-nonprod.cluster_address
}

output "elasticache_redis_nonprod_cluster_alias" {
  value = module.redis-nonprod.cluster_alias
}

Conditional creation

Sometimes you need to have a way to create module resources conditionally but Terraform does not allow to use count inside module block, so the solution is to specify argument enable_elasticache.

# This Elasticache will not be created
module "vpc" {
  source = "InnovateUKGitHub/terraform-module-elasticache"

  enable_elasticache = false
  # ... omitted
}

Inputs

Name	Description	Type	Default	Required
deploy_env	Deployment Environment. Forms part of the unique namespace given to resources	string		yes
vpc_id	ID of the VPC to host the elasticache	string		yes
subnet_group_name	Subnet group for elasticache	string		yes
notification_topic_arn	An Amazon Resource Name (ARN) of an SNS topic to send ElastiCache notifications to	string		yes
purpose	Name to add for uniqueness, eg, prod or nonprod	string	"nonprod"	no
enable_elasticache	Boolean flag to enable or disable elasticache deploy	boolean	true	no
elasticache_clients_sgs	Array of SG ids from which to allow access to Elasticache	list	[]	no
elasticache_family	Elasticache family, eg, redis or memcache	string	"memcached1.4"	no
elasticache_engine	Which engine to use for elasticache (redis/memcached)	string	"memcached"	no
elasticache_port	Which port to use for elasticache (redis/memcached)	string	"11211"	no
elasticache_engine_version	Engine version for elasticache	string	"1.4.34"	no
elasticache_instance_type	Instance type for elasticache	string	"cache.t2.small"	no
elasticache_multi_az	Enable multi AZ	boolean	false	no
elasticache_password	Password for elasticache	string	""	no
num_elasticache_instances	Number of elasticache instances	string	"2"	no
redis_replicas_per_node_group	Redis setting for number of replicas per node group	string	"1"	no
dns_record_ttl	Time To Live for DNS Alias record	string	"60"	no
local_dns_domain_zone_id	ZoneID for Route53 localzone to create record for ealasticache	string		no

Outputs

Name	Description
cluster_address	Cluster/Config fqdn address of elasticache
cluster_alias	Alias to Cluster/Config fqdn address of elasticache created in supplied DNS zone

Authors

Module is maintained by Innovate UK.

License

MIT Licensed. See LICENSE for full details.