» aws_elasticache_replication_group

Provides an ElastiCache Replication Group resource. For working with Memcached or single primary Redis instances (Cluster Mode Disabled), see the aws_elasticache_cluster resource.

» Example Usage

» Redis Cluster Mode Disabled

To create a single shard primary with single read replica:

resource "aws_elasticache_replication_group" "example" {
  automatic_failover_enabled    = true
  availability_zones            = ["us-west-2a", "us-west-2b"]
  replication_group_id          = "tf-rep-group-1"
  replication_group_description = "test description"
  node_type                     = "cache.m3.medium"
  number_cache_clusters         = 2
  parameter_group_name          = "default.redis3.2"
  port                          = 6379

Additional read replicas can be added or removed with the aws_elasticache_cluster resource and its replication_group_id attribute. In this situation, you will need to utilize the lifecycle configuration block with ignore_changes to prevent replication group recreation.

resource "aws_elasticache_replication_group" "example" {
  automatic_failover_enabled    = true
  availability_zones            = ["us-west-2a", "us-west-2b"]
  replication_group_id          = "tf-rep-group-1"
  replication_group_description = "test description"
  node_type                     = "cache.m3.medium"
  number_cache_clusters         = 2
  parameter_group_name          = "default.redis3.2"
  port                          = 6379

  lifecycle {
    ignore_changes = ["number_cache_clusters"]

resource "aws_elasticache_cluster" "replica" {
  count = 1

  cluster_id           = "tf-rep-group-1-${count.index}"
  replication_group_id = "${aws_elasticache_replication_group.example.id}"

» Redis Cluster Mode Enabled

To create two shards with a primary and a single read replica each:

resource "aws_elasticache_replication_group" "baz" {
  replication_group_id          = "tf-redis-cluster"
  replication_group_description = "test description"
  node_type                     = "cache.m1.small"
  port                          = 6379
  parameter_group_name          = "default.redis3.2.cluster.on"
  automatic_failover_enabled    = true
  cluster_mode {
    replicas_per_node_group     = 1
    num_node_groups             = 2

» Argument Reference

The following arguments are supported:

  • replication_group_id – (Required) The replication group identifier. This parameter is stored as a lowercase string.
  • replication_group_description – (Required) A user-created description for the replication group.
  • number_cache_clusters - (Required) The number of cache clusters this replication group will have. If Multi-AZ is enabled , the value of this parameter must be at least 2. Changing this number will force a new resource
  • node_type - (Required) The compute and memory capacity of the nodes in the node group.
  • automatic_failover_enabled - (Optional) Specifies whether a read-only replica will be automatically promoted to read/write primary if the existing primary fails. If true, Multi-AZ is enabled for this replication group. If false, Multi-AZ is disabled for this replication group. Must be enabled for Redis (cluster mode enabled) replication groups. Defaults to false.
  • auto_minor_version_upgrade - (Optional) Specifies whether a minor engine upgrades will be applied automatically to the underlying Cache Cluster instances during the maintenance window. Defaults to true.
  • availability_zones - (Optional) A list of EC2 availability zones in which the replication group's cache clusters will be created. The order of the availability zones in the list is not important.
  • engine - (Optional) The name of the cache engine to be used for the clusters in this replication group. e.g. redis
  • at_rest_encryption_enabled - (Optional) Whether to enable encryption at rest.
  • transit_encryption_enabled - (Optional) Whether to enable encryption in transit.
  • auth_token - (Optional) The password used to access a password protected server. Can be specified only if transit_encryption_enabled = true.
  • engine_version - (Optional) The version number of the cache engine to be used for the cache clusters in this replication group.
  • parameter_group_name - (Optional) The name of the parameter group to associate with this replication group. If this argument is omitted, the default cache parameter group for the specified engine is used.
  • port – (Optional) The port number on which each of the cache nodes will accept connections. For Memcache the default is 11211, and for Redis the default port is 6379.
  • subnet_group_name - (Optional) The name of the cache subnet group to be used for the replication group.
  • security_group_names - (Optional) A list of cache security group names to associate with this replication group.
  • security_group_ids - (Optional) One or more Amazon VPC security groups associated with this replication group. Use this parameter only when you are creating a replication group in an Amazon Virtual Private Cloud
  • snapshot_arns – (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
  • snapshot_name - (Optional) The name of a snapshot from which to restore data into the new node group. Changing the snapshot_name forces a new resource.
  • maintenance_window – (Optional) Specifies the weekly time range for when maintenance on the cache cluster is performed. The format is ddd:hh24:mi-ddd:hh24:mi (24H Clock UTC). The minimum maintenance window is a 60 minute period. Example: sun:05:00-sun:09:00
  • notification_topic_arn – (Optional) An Amazon Resource Name (ARN) of an SNS topic to send ElastiCache notifications to. Example: arn:aws:sns:us-east-1:012345678999:my_sns_topic
  • snapshot_window - (Optional, Redis only) The daily time range (in UTC) during which ElastiCache will begin taking a daily snapshot of your cache cluster. The minimum snapshot window is a 60 minute period. Example: 05:00-09:00
  • snapshot_retention_limit - (Optional, Redis only) The number of days for which ElastiCache will retain automatic cache cluster snapshots before deleting them. For example, if you set SnapshotRetentionLimit to 5, then a snapshot that was taken today will be retained for 5 days before being deleted. If the value of SnapshotRetentionLimit is set to zero (0), backups are turned off. Please note that setting a snapshot_retention_limit is not supported on cache.t1.micro or cache.t2.* cache nodes
  • apply_immediately - (Optional) Specifies whether any modifications are applied immediately, or during the next maintenance window. Default is false.
  • tags - (Optional) A mapping of tags to assign to the resource
  • cluster_mode - (Optional) Create a native redis cluster. automatic_failover_enabled must be set to true. Cluster Mode documented below. Only 1 cluster_mode block is allowed.

Cluster Mode (cluster_mode) supports the following:

  • replicas_per_node_group - (Required) Specify the number of replica nodes in each node group. Valid values are 0 to 5. Changing this number will force a new resource.
  • num_node_groups - (Required) Specify the number of node groups (shards) for this Redis replication group. Changing this number will trigger an online resizing operation before other settings modifications.

» Attributes Reference

The following attributes are exported:

  • id - The ID of the ElastiCache Replication Group.
  • configuration_endpoint_address - The address of the replication group configuration endpoint when cluster mode is enabled.
  • primary_endpoint_address - (Redis only) The address of the endpoint for the primary node in the replication group, if the cluster mode is disabled.

» Timeouts

aws_elasticache_replication_group provides the following Timeouts configuration options:

  • create - (Default 60m) How long to wait for a replication group to be created.
  • delete - (Default 40m) How long to wait for a replication group to be deleted.
  • update - (Default 40m) How long to wait for replication group settings to be updated. This is also separately used for online resize operation completion, if necessary.

» Import

ElastiCache Replication Groups can be imported using the replication_group_id, e.g.

$ terraform import aws_elasticache_replication_group.my_replication_group replication-group-1