Terraform module to provision an ElastiCache Redis Cluster

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Usage

Disruptive changes introduced at version 0.41.0. If upgrading from an earlier version, see migration notes for details.

Note that this uses secure defaults. One of the ways this module can trip users up is with transit_encryption_enabled which is true by default. With this enabled, one does not simply redis-cli in without setting up an stunnel. Amazon provides good documentation on how to connect with it enabled. If this is not desired behavior, set transit_encryption_enabled=false.

This module creates, by default, a new security group for the Elasticache Redis Cluster. When a configuration change (for example, a different security group name) cannot be applied to the security group, Terraform will replace that security group with a new one with the new configuration. In order to allow Terraform to fully manage the security group, you should not place any other resources in (or associate any other resources with) the security group this module creates. Also, in order to keep things from breaking when this module replaces the security group, you should not reference the created security group anywhere else (such as in rules in other security groups). If you want to associate the cluster with a more stable security group that you can reference elsewhere, create that security group outside this module (perhaps with terraform-aws-security-group) and pass the security group ID in via associated_security_group_ids.

Note about zone_id: Previously, zone_id was a string. This caused problems (see #82). Now zone_id should be supplied as a list(string), either empty or with exactly 1 zone ID in order to avoid the problem.

For a complete example, see examples/complete.

For automated tests of the complete example using bats and Terratest (which tests and deploys the example on AWS), see test.

provider "aws" {
  region = var.region
}

module "this" {
  source  = "cloudposse/label/null"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"
  namespace  = var.namespace
  stage      = var.stage
  name       = var.name
}

module "vpc" {
  source = "cloudposse/vpc/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"

  cidr_block = "172.16.0.0/16"

  context = module.this.context
}

module "subnets" {
  source = "cloudposse/dynamic-subnets/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"

  availability_zones   = var.availability_zones
  vpc_id               = module.vpc.vpc_id
  igw_id               = module.vpc.igw_id
  cidr_block           = module.vpc.vpc_cidr_block
  nat_gateway_enabled  = true
  nat_instance_enabled = false

  context = module.this.context
}

module "redis" {
  source = "cloudposse/elasticache-redis/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"

  availability_zones         = var.availability_zones
  zone_id                    = var.zone_id
  vpc_id                     = module.vpc.vpc_id
  allowed_security_group_ids = [module.vpc.vpc_default_security_group_id]
  subnets                    = module.subnets.private_subnet_ids
  cluster_size               = var.cluster_size
  instance_type              = var.instance_type
  apply_immediately          = true
  automatic_failover_enabled = false
  engine_version             = var.engine_version
  family                     = var.family
  at_rest_encryption_enabled = var.at_rest_encryption_enabled
  transit_encryption_enabled = var.transit_encryption_enabled

  parameter = [
    {
      name  = "notify-keyspace-events"
      value = "lK"
    }
  ]

  context = module.this.context
}

Important

In Cloud Posse's examples, we avoid pinning modules to specific versions to prevent discrepancies between the documentation and the latest released versions. However, for your own projects, we strongly advise pinning each module to the exact version you're using. This practice ensures the stability of your infrastructure. Additionally, we recommend implementing a systematic approach for updating versions to avoid unexpected changes.

Examples

Review the complete example to see how to use this module.

Makefile Targets

Available targets:

  help                                Help screen
  help/all                            Display help for all targets
  help/short                          This help short screen
  lint                                Lint terraform code

Requirements

Name	Version
terraform	>= 1.3
aws	>= 4.18

Providers

Name	Version
aws	>= 4.18

Modules

Name	Source	Version
aws_security_group	cloudposse/security-group/aws	2.2.0
dns	cloudposse/route53-cluster-hostname/aws	0.13.0
this	cloudposse/label/null	0.25.0

Resources

Name	Type
aws_cloudwatch_metric_alarm.cache_cpu	resource
aws_cloudwatch_metric_alarm.cache_memory	resource
aws_elasticache_parameter_group.default	resource
aws_elasticache_replication_group.default	resource
aws_elasticache_subnet_group.default	resource

Inputs

Name	Description	Type	Default	Required
additional_security_group_rules	A list of Security Group rule objects to add to the created security group, in addition to the ones this module normally creates. (To suppress the module's rules, set create_security_group to false and supply your own security group via associated_security_group_ids.) The keys and values of the objects are fully compatible with the aws_security_group_rule resource, except for security_group_id which will be ignored, and the optional "key" which, if provided, must be unique and known at "plan" time. To get more info see https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group_rule .	list(any)	[]	no
additional_tag_map	Additional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id. This is for some rare cases where resources want additional configuration of tags and therefore take a list of maps with tag key, value, and additional configuration.	map(string)	{}	no
alarm_actions	Alarm action list	list(string)	[]	no
alarm_cpu_threshold_percent	CPU threshold alarm level	number	75	no
alarm_memory_threshold_bytes	Ram threshold alarm level	number	10000000	no
allow_all_egress	If true, the created security group will allow egress on all ports and protocols to all IP address. If this is false and no egress rules are otherwise specified, then no egress will be allowed. Defaults to true unless the deprecated egress_cidr_blocks is provided and is not ["0.0.0.0/0"], in which case defaults to false.	bool	null	no
allowed_cidr_blocks	DEPRECATED: Use additional_security_group_rules instead. Historical description: List of CIDR blocks that are allowed ingress to the cluster's Security Group created in the module	list(string)	[]	no
allowed_security_group_ids	A list of IDs of Security Groups to allow access to the security group created by this module.	list(string)	[]	no
allowed_security_groups	DEPRECATED: Use allowed_security_group_ids instead.	list(string)	[]	no
apply_immediately	Apply changes immediately	bool	true	no
associated_security_group_ids	A list of IDs of Security Groups to associate the created resource with, in addition to the created security group. These security groups will not be modified and, if create_security_group is false, must provide all the required access.	list(string)	[]	no
at_rest_encryption_enabled	Enable encryption at rest	bool	false	no
attributes	ID element. Additional attributes (e.g. workers or cluster) to add to id, in the order they appear in the list. New attributes are appended to the end of the list. The elements of the list are joined by the delimiter and treated as a single ID element.	list(string)	[]	no
auth_token	Auth token for password protecting redis, transit_encryption_enabled must be set to true. Password must be longer than 16 chars	string	null	no
auto_minor_version_upgrade	Specifies whether minor version engine upgrades will be applied automatically to the underlying Cache Cluster instances during the maintenance window. Only supported if the engine version is 6 or higher.	bool	null	no
automatic_failover_enabled	Automatic failover (Not available for T1/T2 instances)	bool	false	no
availability_zones	Availability zone IDs	list(string)	[]	no
cloudwatch_metric_alarms_enabled	Boolean flag to enable/disable CloudWatch metrics alarms	bool	false	no
cluster_mode_enabled	Flag to enable/disable creation of a native redis cluster. automatic_failover_enabled must be set to true. Only 1 cluster_mode block is allowed	bool	false	no
cluster_mode_num_node_groups	Number of node groups (shards) for this Redis replication group. Changing this number will trigger an online resizing operation before other settings modifications	number	0	no
cluster_mode_replicas_per_node_group	Number of replica nodes in each node group. Valid values are 0 to 5. Changing this number will force a new resource	number	0	no
cluster_size	Number of nodes in cluster. Ignored when cluster_mode_enabled == true	number	1	no
context	Single object for setting entire context at once. See description of individual variables for details. Leave string and numeric variables as null to use default value. Individual variable settings (non-null) override settings in context object, except for attributes, tags, and additional_tag_map, which are merged.	any	{ "additional_tag_map": {}, "attributes": [], "delimiter": null, "descriptor_formats": {}, "enabled": true, "environment": null, "id_length_limit": null, "label_key_case": null, "label_order": [], "label_value_case": null, "labels_as_tags": [ "unset" ], "name": null, "namespace": null, "regex_replace_chars": null, "stage": null, "tags": {}, "tenant": null }	no
create_parameter_group	Whether new parameter group should be created. Set to false if you want to use existing parameter group	bool	true	no
create_security_group	Set true to create and configure a new security group. If false, associated_security_group_ids must be provided.	bool	true	no
data_tiering_enabled	Enables data tiering. Data tiering is only supported for replication groups using the r6gd node type.	bool	false	no
delimiter	Delimiter to be used between ID elements. Defaults to - (hyphen). Set to "" to use no delimiter at all.	string	null	no
description	Description of elasticache replication group	string	null	no
descriptor_formats	Describe additional descriptors to be output in the descriptors output map. Map of maps. Keys are names of descriptors. Values are maps of the form {<br> format = string<br> labels = list(string)<br>} (Type is any so the map values can later be enhanced to provide additional options.) format is a Terraform format string to be passed to the format() function. labels is a list of labels, in order, to pass to format() function. Label values will be normalized before being passed to format() so they will be identical to how they appear in id. Default is {} (descriptors output will be empty).	any	{}	no
dns_subdomain	The subdomain to use for the CNAME record. If not provided then the CNAME record will use var.name.	string	""	no
egress_cidr_blocks	DEPRECATED: Use allow_all_egress and additional_security_group_rules instead. Historical description: Outbound traffic address. Historical default: ["0.0.0.0/0"]	list(any)	null	no
elasticache_subnet_group_name	Subnet group name for the ElastiCache instance	string	""	no
enabled	Set to false to prevent the module from creating any resources	bool	null	no
engine_version	Redis engine version	string	"4.0.10"	no
environment	ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'	string	null	no
existing_security_groups	DEPRECATED: Use associated_security_group_ids instead. Historical description: List of existing Security Group IDs to place the cluster into. Set use_existing_security_groups to true to enable using existing_security_groups as Security Groups for the cluster.	list(string)	[]	no
family	Redis family	string	"redis4.0"	no
final_snapshot_identifier	The name of your final node group (shard) snapshot. ElastiCache creates the snapshot from the primary node in the cluster. If omitted, no final snapshot will be made.	string	null	no
id_length_limit	Limit id to this many characters (minimum 6). Set to 0 for unlimited length. Set to null for keep the existing setting, which defaults to 0. Does not affect id_full.	number	null	no
inline_rules_enabled	NOT RECOMMENDED. Create rules "inline" instead of as separate aws_security_group_rule resources. See #20046 for one of several issues with inline rules. See this post for details on the difference between inline rules and rule resources.	bool	false	no
instance_type	Elastic cache instance type	string	"cache.t2.micro"	no
kms_key_id	The ARN of the key that you wish to use if encrypting at rest. If not supplied, uses service managed encryption. at_rest_encryption_enabled must be set to true	string	null	no
label_key_case	Controls the letter case of the tags keys (label names) for tags generated by this module. Does not affect keys of tags passed in via the tags input. Possible values: lower, title, upper. Default value: title.	string	null	no
label_order	The order in which the labels (ID elements) appear in the id. Defaults to ["namespace", "environment", "stage", "name", "attributes"]. You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.	list(string)	null	no
label_value_case	Controls the letter case of ID elements (labels) as included in id, set as tag values, and output by this module individually. Does not affect values of tags passed in via the tags input. Possible values: lower, title, upper and none (no transformation). Set this to title and set delimiter to "" to yield Pascal Case IDs. Default value: lower.	string	null	no
labels_as_tags	Set of labels (ID elements) to include as tags in the tags output. Default is to include all labels. Tags with empty values will not be included in the tags output. Set to [] to suppress all generated tags. Notes: The value of the name tag, if included, will be the id, not the name. Unlike other null-label inputs, the initial setting of labels_as_tags cannot be changed in later chained modules. Attempts to change it will be silently ignored.	set(string)	[ "default" ]	no
log_delivery_configuration	The log_delivery_configuration block allows the streaming of Redis SLOWLOG or Redis Engine Log to CloudWatch Logs or Kinesis Data Firehose. Max of 2 blocks.	list(map(any))	[]	no
maintenance_window	Maintenance window	string	"wed:03:00-wed:04:00"	no
multi_az_enabled	Multi AZ (Automatic Failover must also be enabled. If Cluster Mode is enabled, Multi AZ is on by default, and this setting is ignored)	bool	false	no
name	ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'. This is the only ID element not also included as a tag. The "name" tag is set to the full id string. There is no tag with the value of the name input.	string	null	no
namespace	ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique	string	null	no
notification_topic_arn	Notification topic arn	string	""	no
ok_actions	The list of actions to execute when this alarm transitions into an OK state from any other state. Each action is specified as an Amazon Resource Number (ARN)	list(string)	[]	no
parameter	A list of Redis parameters to apply. Note that parameters may differ from one Redis family to another	list(object({ name = string value = string }))	[]	no
parameter_group_description	Managed by Terraform	string	null	no
parameter_group_name	Override the default parameter group name	string	null	no
port	Redis port	number	6379	no
preserve_security_group_id	When false and create_before_destroy is true, changes to security group rules cause a new security group to be created with the new rules, and the existing security group is then replaced with the new one, eliminating any service interruption. When true or when changing the value (from false to true or from true to false), existing security group rules will be deleted before new ones are created, resulting in a service interruption, but preserving the security group itself. NOTE: Setting this to true does not guarantee the security group will never be replaced, it only keeps changes to the security group rules from triggering a replacement. See the README for further discussion.	bool	false	no
regex_replace_chars	Terraform regular expression (regex) string. Characters matching the regex will be removed from the ID elements. If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.	string	null	no
replication_group_id	Replication group ID with the following constraints: A name must contain from 1 to 20 alphanumeric characters or hyphens. The first character must be a letter. A name cannot end with a hyphen or contain two consecutive hyphens.	string	""	no
revoke_rules_on_delete	Instruct Terraform to revoke all of the Security Group's attached ingress and egress rules before deleting the security group itself. This is normally not needed.	bool	false	no
security_group_create_before_destroy	Set true to enable Terraform create_before_destroy behavior on the created security group. We only recommend setting this false if you are upgrading this module and need to keep the existing security group from being replaced. Note that changing this value will always cause the security group to be replaced.	bool	true	no
security_group_create_timeout	How long to wait for the security group to be created.	string	"10m"	no
security_group_delete_timeout	How long to retry on DependencyViolation errors during security group deletion.	string	"15m"	no
security_group_description	The description to assign to the created Security Group. Warning: Changing the description causes the security group to be replaced. Set this to null to maintain parity with releases <= 0.34.0.	string	"Security group for Elasticache Redis"	no
security_group_name	The name to assign to the security group. Must be unique within the VPC. If not provided, will be derived from the null-label.context passed in. If create_before_destroy is true, will be used as a name prefix.	list(string)	[]	no
snapshot_arns	A single-element string list containing an Amazon Resource Name (ARN) of a Redis RDB snapshot file stored in Amazon S3. Example: arn:aws:s3:::my_bucket/snapshot1.rdb	list(string)	[]	no
snapshot_name	The name of a snapshot from which to restore data into the new node group. Changing the snapshot_name forces a new resource.	string	null	no
snapshot_retention_limit	The number of days for which ElastiCache will retain automatic cache cluster snapshots before deleting them.	number	0	no
snapshot_window	The daily time range (in UTC) during which ElastiCache will begin taking a daily snapshot of your cache cluster.	string	"06:30-07:30"	no
stage	ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'	string	null	no
subnets	Subnet IDs	list(string)	[]	no
tags	Additional tags (e.g. {'BusinessUnit': 'XYZ'}). Neither the tag keys nor the tag values will be modified by this module.	map(string)	{}	no
target_security_group_id	The ID of an existing Security Group to which Security Group rules will be assigned. The Security Group's name and description will not be changed. Not compatible with inline_rules_enabled or revoke_rules_on_delete. If not provided (the default), this module will create a security group.	list(string)	[]	no
tenant	ID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is for	string	null	no
transit_encryption_enabled	Set true to enable encryption in transit. Forced true if var.auth_token is set. If this is enabled, use the following guide to access redis.	bool	true	no
use_existing_security_groups	DEPRECATED: Use create_security_group instead. Historical description: Flag to enable/disable creation of Security Group in the module. Set to true to disable Security Group creation and provide a list of existing security Group IDs in existing_security_groups to place the cluster into. Historical default: false	bool	null	no
user_group_ids	User Group ID to associate with the replication group	list(string)	null	no
vpc_id	VPC ID	string	n/a	yes
zone_id	Route53 DNS Zone ID as list of string (0 or 1 items). If empty, no custom DNS name will be published. If the list contains a single Zone ID, a custom DNS name will be pulished in that zone. Can also be a plain string, but that use is DEPRECATED because of Terraform issues.	any	[]	no

Outputs

Name	Description
arn	Elasticache Replication Group ARN
cluster_enabled	Indicates if cluster mode is enabled
endpoint	Redis primary or configuration endpoint, whichever is appropriate for the given cluster mode
engine_version_actual	The running version of the cache engine
host	Redis hostname
id	Redis cluster ID
member_clusters	Redis cluster members
port	Redis port
reader_endpoint_address	The address of the endpoint for the reader node in the replication group, if the cluster mode is disabled.
security_group_id	The ID of the created security group
security_group_name	The name of the created security group

Related Projects

Check out these related projects.

• terraform-aws-security-group - Terraform module to provision an AWS Security Group.
• terraform-null-label - Terraform module designed to generate consistent names and tags for resources. Use terraform-null-label to implement a strict naming convention.

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