AWS CloudFormation
User Guide (Version )

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AWS::ElastiCache::CacheCluster

The AWS::ElastiCache::CacheCluster type creates an Amazon ElastiCache cache cluster.

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{ "Type" : "AWS::ElastiCache::CacheCluster", "Properties" : { "AutoMinorVersionUpgrade" : Boolean, "AZMode" : String, "CacheNodeType" : String, "CacheParameterGroupName" : String, "CacheSecurityGroupNames" : [ String, ... ], "CacheSubnetGroupName" : String, "ClusterName" : String, "Engine" : String, "EngineVersion" : String, "NotificationTopicArn" : String, "NumCacheNodes" : Integer, "Port" : Integer, "PreferredAvailabilityZone" : String, "PreferredAvailabilityZones" : [ String, ... ], "PreferredMaintenanceWindow" : String, "SnapshotArns" : [ String, ... ], "SnapshotName" : String, "SnapshotRetentionLimit" : Integer, "SnapshotWindow" : String, "Tags" : [ Tag, ... ], "VpcSecurityGroupIds" : [ String, ... ] } }

YAML

Type: AWS::ElastiCache::CacheCluster Properties: AutoMinorVersionUpgrade: Boolean AZMode: String CacheNodeType: String CacheParameterGroupName: String CacheSecurityGroupNames: - String CacheSubnetGroupName: String ClusterName: String Engine: String EngineVersion: String NotificationTopicArn: String NumCacheNodes: Integer Port: Integer PreferredAvailabilityZone: String PreferredAvailabilityZones: - String PreferredMaintenanceWindow: String SnapshotArns: - String SnapshotName: String SnapshotRetentionLimit: Integer SnapshotWindow: String Tags: - Tag VpcSecurityGroupIds: - String

Properties

AutoMinorVersionUpgrade

This parameter is currently disabled.

Required: No

Type: Boolean

Update requires: No interruption

AZMode

Specifies whether the nodes in this Memcached cluster are created in a single Availability Zone or created across multiple Availability Zones in the cluster's region.

This parameter is only supported for Memcached clusters.

If the AZMode and PreferredAvailabilityZones are not specified, ElastiCache assumes single-az mode.

Required: No

Type: String

Allowed Values: cross-az | single-az

Update requires: Some interruptions

CacheNodeType

The compute and memory capacity of the nodes in the node group (shard).

The following node types are supported by ElastiCache. Generally speaking, the current generation types provide more memory and computational power at lower cost when compared to their equivalent previous generation counterparts.

  • General purpose:

    • Current generation:

      M5 node types: cache.m5.large, cache.m5.xlarge, cache.m5.2xlarge, cache.m5.4xlarge, cache.m5.12xlarge, cache.m5.24xlarge

      M4 node types: cache.m4.large, cache.m4.xlarge, cache.m4.2xlarge, cache.m4.4xlarge, cache.m4.10xlarge

      T2 node types: cache.t2.micro, cache.t2.small, cache.t2.medium

    • Previous generation: (not recommended)

      T1 node types: cache.t1.micro

      M1 node types: cache.m1.small, cache.m1.medium, cache.m1.large, cache.m1.xlarge

      M3 node types: cache.m3.medium, cache.m3.large, cache.m3.xlarge, cache.m3.2xlarge

  • Compute optimized:

    • Previous generation: (not recommended)

      C1 node types: cache.c1.xlarge

  • Memory optimized:

    • Current generation:

      R5 node types: cache.r5.large, cache.r5.xlarge, cache.r5.2xlarge, cache.r5.4xlarge, cache.r5.12xlarge, cache.r5.24xlarge

      R4 node types: cache.r4.large, cache.r4.xlarge, cache.r4.2xlarge, cache.r4.4xlarge, cache.r4.8xlarge, cache.r4.16xlarge

    • Previous generation: (not recommended)

      M2 node types: cache.m2.xlarge, cache.m2.2xlarge, cache.m2.4xlarge

      R3 node types: cache.r3.large, cache.r3.xlarge, cache.r3.2xlarge, cache.r3.4xlarge, cache.r3.8xlarge

Additional node type info

  • All current generation instance types are created in Amazon VPC by default.

  • Redis append-only files (AOF) are not supported for T1 or T2 instances.

  • Redis Multi-AZ with automatic failover is not supported on T1 instances.

  • Redis configuration variables appendonly and appendfsync are not supported on Redis version 2.8.22 and later.

Required: Yes

Type: String

Update requires: No interruption

CacheParameterGroupName

The name of the parameter group to associate with this cluster. If this argument is omitted, the default parameter group for the specified engine is used. You cannot use any parameter group which has cluster-enabled='yes' when creating a cluster.

Required: No

Type: String

Update requires: No interruption

CacheSecurityGroupNames

A list of security group names to associate with this cluster.

Use this parameter only when you are creating a cluster outside of an Amazon Virtual Private Cloud (Amazon VPC).

Required: No

Type: List of String

Update requires: No interruption

CacheSubnetGroupName

The name of the subnet group to be used for the cluster.

Use this parameter only when you are creating a cluster in an Amazon Virtual Private Cloud (Amazon VPC).

Important

If you're going to launch your cluster in an Amazon VPC, you need to create a subnet group before you start creating a cluster. For more information, see Subnets and Subnet Groups.

Required: No

Type: String

Update requires: Replacement

ClusterName

A name for the cache cluster. If you don't specify a name, AWSCloudFormation generates a unique physical ID and uses that ID for the cache cluster. For more information, see Name Type.

The name must contain 1 to 20 alphanumeric characters or hyphens. The name must start with a letter and cannot end with a hyphen or contain two consecutive hyphens.

Required: No

Type: String

Update requires: Replacement

Engine

The name of the cache engine to be used for this cluster.

Valid values for this parameter are: memcached | redis

Required: Yes

Type: String

Update requires: Replacement

EngineVersion

The version number of the cache engine to be used for this cluster. To view the supported cache engine versions, use the DescribeCacheEngineVersions operation.

Important: You can upgrade to a newer engine version (see Selecting a Cache Engine and Version), but you cannot downgrade to an earlier engine version. If you want to use an earlier engine version, you must delete the existing cluster or replication group and create it anew with the earlier engine version.

Required: No

Type: String

Update requires: No interruption

NotificationTopicArn

The Amazon Resource Name (ARN) of the Amazon Simple Notification Service (SNS) topic to which notifications are sent.

Note

The Amazon SNS topic owner must be the same as the cluster owner.

Required: No

Type: String

Update requires: No interruption

NumCacheNodes

The number of cache nodes that the cache cluster should have.

Note

However, if the PreferredAvailabilityZone and PreferredAvailabilityZones properties were not previously specified and you don't specify any new values, an update requires replacement.

Required: Yes

Type: Integer

Update requires: Some interruptions

Port

The port number on which each of the cache nodes accepts connections.

Required: No

Type: Integer

Update requires: Replacement

PreferredAvailabilityZone

The EC2 Availability Zone in which the cluster is created.

All nodes belonging to this Memcached cluster are placed in the preferred Availability Zone. If you want to create your nodes across multiple Availability Zones, use PreferredAvailabilityZones.

Default: System chosen Availability Zone.

Required: No

Type: String

Update requires: Some interruptions

PreferredAvailabilityZones

A list of the Availability Zones in which cache nodes are created. The order of the zones in the list is not important.

This option is only supported on Memcached.

Note

If you are creating your cluster in an Amazon VPC (recommended) you can only locate nodes in Availability Zones that are associated with the subnets in the selected subnet group.

The number of Availability Zones listed must equal the value of NumCacheNodes.

If you want all the nodes in the same Availability Zone, use PreferredAvailabilityZone instead, or repeat the Availability Zone multiple times in the list.

Default: System chosen Availability Zones.

Required: No

Type: List of String

Update requires: Some interruptions

PreferredMaintenanceWindow

Specifies the weekly time range during which maintenance on the cluster is performed. It is specified as a range in the format ddd:hh24:mi-ddd:hh24:mi (24H Clock UTC). The minimum maintenance window is a 60 minute period. Valid values for ddd are:

Specifies the weekly time range during which maintenance on the cluster is performed. It is specified as a range in the format ddd:hh24:mi-ddd:hh24:mi (24H Clock UTC). The minimum maintenance window is a 60 minute period.

Valid values for ddd are:

  • sun

  • mon

  • tue

  • wed

  • thu

  • fri

  • sat

Example: sun:23:00-mon:01:30

Required: No

Type: String

Update requires: No interruption

SnapshotArns

A single-element string list containing an Amazon Resource Name (ARN) that uniquely identifies a Redis RDB snapshot file stored in Amazon S3. The snapshot file is used to populate the node group (shard). The Amazon S3 object name in the ARN cannot contain any commas.

Note

This parameter is only valid if the Engine parameter is redis.

Example of an Amazon S3 ARN: arn:aws:s3:::my_bucket/snapshot1.rdb

Required: No

Type: List of String

Update requires: Replacement

SnapshotName

The name of a Redis snapshot from which to restore data into the new node group (shard). The snapshot status changes to restoring while the new node group (shard) is being created.

Note

This parameter is only valid if the Engine parameter is redis.

Required: No

Type: String

Update requires: Replacement

SnapshotRetentionLimit

The number of days for which ElastiCache retains automatic snapshots before deleting them. For example, if you set SnapshotRetentionLimit to 5, a snapshot taken today is retained for 5 days before being deleted.

Note

This parameter is only valid if the Engine parameter is redis.

Default: 0 (i.e., automatic backups are disabled for this cache cluster).

Required: No

Type: Integer

Update requires: No interruption

SnapshotWindow

The daily time range (in UTC) during which ElastiCache begins taking a daily snapshot of your node group (shard).

Example: 05:00-09:00

If you do not specify this parameter, ElastiCache automatically chooses an appropriate time range.

Note

This parameter is only valid if the Engine parameter is redis.

Required: No

Type: String

Update requires: No interruption

Tags

A list of cost allocation tags to be added to this resource.

Required: No

Type: List of Tag

Update requires: No interruption

VpcSecurityGroupIds

One or more VPC security groups associated with the cluster.

Use this parameter only when you are creating a cluster in an Amazon Virtual Private Cloud (Amazon VPC).

Required: No

Type: List of String

Update requires: No interruption

Return Values

Ref

When the logical ID of this resource is provided to the Ref intrinsic function, Ref returns the resource name.

For more information about using the Ref function, see Ref.

Fn::GetAtt

The Fn::GetAtt intrinsic function returns a value for a specified attribute of this type. The following are the available attributes and sample return values.

For more information about using the Fn::GetAtt intrinsic function, see Fn::GetAtt.

ConfigurationEndpoint.Address

The DNS hostname of the cache node.

Note

Redis (cluster mode disabled) replication groups don't have this attribute. Therefore, Fn::GetAtt returns a value for this attribute only if the replication group is clustered. Otherwise, Fn::GetAtt fails.

ConfigurationEndpoint.Port

The port number of the configuration endpoint for the Memcached cache cluster.

RedisEndpoint.Address

The DNS address of the configuration endpoint for the Redis cache cluster.

RedisEndpoint.Port

The port number of the configuration endpoint for the Redis cache cluster.

Examples

Cluster in a Default VPC

The following snippet describes an Elasticache cluster in a security group that is in a default VPC. Usually, a security group in a VPC requires the VPC ID to be specified. In this case, no VPC ID is needed because the security group uses the default VPC. If you want to specify a VPC for the security group, specify its VpcId property.

For the cache cluster, the VpcSecurityGroupIds property is used to associate the cluster with the security group. Because the VpcSecurityGroupIds property requires security group IDs (not security group names), the template snippet uses the Fn::GetAtt function instead of a Ref function on the ElasticacheSecurityGroup resource. The Ref function will return the security group name. If you specify a VPC ID for the security group, Ref returns the security group ID.

Note that InstanceSecurityGroup refers to the logical name of a security group that is not actually defined in this example. To learn more about the SourceSecurityGroupName property, see AWS::EC2::SecurityGroupIngress.

JSON

{ "ElasticacheSecurityGroup": { "Type": "AWS::EC2::SecurityGroup", "Properties": { "GroupDescription": "Elasticache Security Group", "SecurityGroupIngress": [ { "IpProtocol": "tcp", "FromPort": "11211", "ToPort": "11211", "SourceSecurityGroupName": { "Ref": "InstanceSecurityGroup" } } ] } }, "ElasticacheCluster": { "Type": "AWS::ElastiCache::CacheCluster", "Properties": { "AutoMinorVersionUpgrade": "true", "Engine": "memcached", "CacheNodeType": "cache.t2.micro", "NumCacheNodes": "1", "VpcSecurityGroupIds": [ { "Fn::GetAtt": [ "ElasticacheSecurityGroup", "GroupId" ] } ] } } }

YAML

ElasticacheSecurityGroup: Type: 'AWS::EC2::SecurityGroup' Properties: GroupDescription: Elasticache Security Group SecurityGroupIngress: - IpProtocol: tcp FromPort: '11211' ToPort: '11211' SourceSecurityGroupName: !Ref InstanceSecurityGroup ElasticacheCluster: Type: 'AWS::ElastiCache::CacheCluster' Properties: AutoMinorVersionUpgrade: 'true' Engine: memcached CacheNodeType: cache.t2.micro NumCacheNodes: '1' VpcSecurityGroupIds: - !GetAtt - ElasticacheSecurityGroup - GroupId

Memcached Nodes in Multiple Availability Zones

The following example launches a cache cluster with three nodes, where two nodes are created in us-west-2a and one is created in us-west-2b.

JSON

{ "myCacheCluster": { "Type": "AWS::ElastiCache::CacheCluster", "Properties": { "AZMode": "cross-az", "CacheNodeType": "cache.m3.medium", "Engine": "memcached", "NumCacheNodes": "3", "PreferredAvailabilityZones": [ "us-west-2a", "us-west-2a", "us-west-2b" ] } } }

YAML

myCacheCluster: Type: 'AWS::ElastiCache::CacheCluster' Properties: AZMode: cross-az CacheNodeType: cache.m3.medium Engine: memcached NumCacheNodes: '3' PreferredAvailabilityZones: - us-west-2a - us-west-2a - us-west-2b

See Also