Module: `elasticache-redis`

Terraform module to provision an ElastiCache Redis Cluster or Serverless instance.

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 / Serverless Instance. 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 or examples/serverless.

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
}

Examples

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

Variables

Required Variables

vpc_id (string) required: VPC ID

Optional Variables

additional_security_group_rules (list(any)) optional

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 .

Default value: [ ]

alarm_actions (list(string)) optional

Alarm action list

Default value: [ ]

alarm_cpu_threshold_percent (number) optional

CPU threshold alarm level

Default value: 75

alarm_memory_threshold_bytes (number) optional

Ram threshold alarm level

Default value: 10000000

allow_all_egress (bool) optional

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.

Default value: null

allowed_cidr_blocks (list(string)) optional

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

Default value: [ ]

allowed_security_group_ids (list(string)) optional

A list of IDs of Security Groups to allow access to the security group created by this module.

Default value: [ ]

allowed_security_groups (list(string)) optional

DEPRECATED: Use allowed_security_group_ids instead.

Default value: [ ]

apply_immediately (bool) optional

Apply changes immediately

Default value: true

associated_security_group_ids (list(string)) optional

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.

Default value: [ ]

at_rest_encryption_enabled (bool) optional

Enable encryption at rest

Default value: false

auth_token (string) optional

Auth token for password protecting redis, transit_encryption_enabled must be set to true. Password must be longer than 16 chars

Default value: null

auth_token_update_strategy (string) optional

Strategy to use when updating the auth_token. Valid values are SET, ROTATE, and DELETE. Defaults to ROTATE.

Default value: "ROTATE"

auto_minor_version_upgrade (bool) optional

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.

Default value: null

automatic_failover_enabled (bool) optional

Automatic failover (Not available for T1/T2 instances)

Default value: false

availability_zones (list(string)) optional

Availability zone IDs

Default value: [ ]

cloudwatch_metric_alarms_enabled (bool) optional

Boolean flag to enable/disable CloudWatch metrics alarms

Default value: false

cluster_mode_enabled (bool) optional

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

Default value: false

cluster_mode_num_node_groups (number) optional

Number of node groups (shards) for this Redis replication group. Changing this number will trigger an online resizing operation before other settings modifications

Default value: 0

cluster_mode_replicas_per_node_group (number) optional

Number of replica nodes in each node group. Valid values are 0 to 5. Changing this number will force a new resource

Default value: 0

cluster_size (number) optional

Number of nodes in cluster. Ignored when cluster_mode_enabled == true

Default value: 1

create_parameter_group (bool) optional

Whether new parameter group should be created. Set to false if you want to use existing parameter group

Default value: true

create_security_group (bool) optional

Set true to create and configure a new security group. If false, associated_security_group_ids must be provided.

Default value: true

data_tiering_enabled (bool) optional

Enables data tiering. Data tiering is only supported for replication groups using the r6gd node type.

Default value: false

description (string) optional

Description of elasticache replication group

Default value: null

dns_subdomain (string) optional

The subdomain to use for the CNAME record. If not provided then the CNAME record will use var.name.

Default value: ""

egress_cidr_blocks (list(any)) optional

DEPRECATED: Use allow_all_egress and additional_security_group_rules instead.
Historical description: Outbound traffic address.
Historical default: ["0.0.0.0/0"]

Default value: null

elasticache_subnet_group_name (string) optional

Subnet group name for the ElastiCache instance

Default value: ""

engine (string) optional

Name of the cache engine

Default value: "redis"

engine_version (string) optional

Version number of the cache engine

Default value: "7.1"

existing_security_groups (list(string)) optional

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.

Default value: [ ]

family (string) optional

The family of the ElastiCache parameter group

Default value: "redis7"

final_snapshot_identifier (string) optional

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.

Default value: null

global_replication_group_id (string) optional

The ID of the global replication group to which this replication group should belong. If this parameter is specified, the replication group is added to the specified global replication group as a secondary replication group; otherwise, the replication group is not part of any global replication group. If global_replication_group_id is set, the num_node_groups parameter cannot be set.

Default value: null

inline_rules_enabled (bool) optional

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.

Default value: false

instance_type (string) optional

Elastic cache instance type

Default value: "cache.t2.micro"

kms_key_id (string) optional

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

Default value: null

log_delivery_configuration (list(map(any))) optional

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.

Default value: [ ]

maintenance_window (string) optional

Maintenance window

Default value: "wed:03:00-wed:04:00"

multi_az_enabled (bool) optional

Multi AZ (Automatic Failover must also be enabled. If Cluster Mode is enabled, Multi AZ is on by default, and this setting is ignored)

Default value: false

network_type (string) optional

The network type of the cluster. Valid values: ipv4, ipv6, dual_stack.

Default value: "ipv4"

notification_topic_arn (string) optional

Notification topic arn

Default value: ""

ok_actions (list(string)) optional

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)

Default value: [ ]

parameter optional

A list of Redis parameters to apply. Note that parameters may differ from one Redis family to another

Type:

list(object({
name  = string
value = string
}))

Default value: [ ]

parameter_group_description (string) optional

Managed by Terraform

Default value: null

parameter_group_name (string) optional

Override the default parameter group name

Default value: null

port (number) optional

Port number on which the cache nodes will accept connections

Default value: 6379

preserve_security_group_id (bool) optional

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.

Default value: false

replication_group_id (string) optional

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.

Default value: ""

revoke_rules_on_delete (bool) optional

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.

Default value: false

security_group_create_before_destroy (bool) optional

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.

Default value: true

security_group_create_timeout (string) optional

How long to wait for the security group to be created.

Default value: "10m"

security_group_delete_timeout (string) optional

How long to retry on DependencyViolation errors during security group deletion.

Default value: "15m"

security_group_description (string) optional

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.

Default value: "Security group for Elasticache Redis"

security_group_name (list(string)) optional

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.

Default value: [ ]

serverless_cache_usage_limits (map(any)) optional

The usage limits for the serverless cache

Default value: { }

serverless_enabled (bool) optional

Flag to enable/disable creation of a serverless redis cluster

Default value: false

serverless_major_engine_version (string) optional

The major version of the engine to use for the serverless cluster

Default value: "7"

serverless_snapshot_arns_to_restore (list(string)) optional

The list of ARN(s) of the snapshot that the new serverless cache will be created from. Available for Redis only.

Default value: [ ]

serverless_snapshot_time (string) optional

The daily time that snapshots will be created from the serverless cache.

Default value: "06:00"

serverless_user_group_id (string) optional

User Group ID to associate with the replication group

Default value: null

snapshot_arns (list(string)) optional

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

Default value: [ ]

snapshot_name (string) optional

The name of a snapshot from which to restore data into the new node group. Changing the snapshot_name forces a new resource.

Default value: null

snapshot_retention_limit (number) optional

The number of days for which ElastiCache will retain automatic cache cluster snapshots before deleting them. Set a value to enable automated backups on the cache. If the value of snapshot_retention_limit is set to zero (0), backups are turned off.

Default value: 0

snapshot_window (string) optional

The daily time range (in UTC) during which ElastiCache will begin taking a daily snapshot of your cache cluster.

Default value: "06:30-07:30"

subnets (list(string)) optional

Subnet IDs

Default value: [ ]

target_security_group_id (list(string)) optional

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.

Default value: [ ]

transit_encryption_enabled (bool) optional

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.

Default value: true

transit_encryption_mode (string) optional

A setting that enables clients to migrate to in-transit encryption with no downtime. Valid values are preferred and required. When enabling encryption on an existing replication group, this must first be set to preferred before setting it to required in a subsequent apply. See the TransitEncryptionMode field in the CreateReplicationGroup API documentation for additional details."

Default value: null

use_existing_security_groups (bool) optional

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

Default value: null

user_group_ids (list(string)) optional

User Group ID to associate with the replication group

Default value: null

zone_id (any) optional

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.

Default value: [ ]

Context Variables

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

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.

Required: No

Default value: { }

attributes (list(string)) optional

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.

Required: No

Default value: [ ]

context (any) optional

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.

Required: No

Default value:

{
  "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
}

delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.

Required: No

Default value: null

descriptor_formats (any) optional

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).

Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

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.

Required: No

Default value: null

label_key_case (string) optional

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.

Required: No

Default value: null

label_order (list(string)) optional

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.

Required: No

Default value: null

label_value_case (string) optional

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.

Required: No

Default value: null

labels_as_tags (set(string)) optional

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.

Required: No

Default value:

[
  "default"
]

name (string) optional

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.

Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

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.

Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.

Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs

arn: Elasticache Replication Group ARN
cluster_enabled: Indicates if cluster mode is enabled
endpoint: Redis primary, configuration or serverless endpoint , whichever is appropriate for the given configuration
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 or serverless is being used.
security_group_id: The ID of the created security group
security_group_name: The name of the created security group
serverless_enabled: Indicates if serverless mode is enabled
transit_encryption_mode: The transit encryption mode of the replication group

Dependencies

Requirements

terraform, version: >= 1.3
aws, version: >= 5.73.0

Providers

aws, version: >= 5.73.0

Modules

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

Resources

The following resources are used by this module:

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_serverless_cache.default (resource)
aws_elasticache_subnet_group.default (resource)

Data Sources

The following data sources are used by this module:

Module: elasticache-redis

Usage​

Examples​

Variables​

Required Variables​

Optional Variables​

Context Variables​

Outputs​

Dependencies​

Requirements​

Providers​

Modules​

Resources​

Data Sources​

Module: `elasticache-redis`

Usage

Examples

Variables

Required Variables

Optional Variables

Context Variables

Outputs

Dependencies

Requirements

Providers

Modules

Resources

Data Sources