elasticache-redis CfHighlander component

Requirements

Parameters

Name	Use	Default	Global	Type	Allowed Values
EnvironmentName	Tagging	dev	true	String
EnvironmentType	Tagging	development	true	String	['development','production']
DnsDomain	Zone to launch redis record in		true	String
VPCId	ID of the VPC to launch Redis in		false	AWS::EC2::VPC::Id
InstanceType	The compute and memory capacity of the nodes in the node group (shard)	t3.small	false	String
Subnets	list of subnet ciders for the redis cluster		false	CommaDelimitedList
SnapshotName	The name of a snapshot from which to restore data into the new replication group		false	String
SnapshotArns	A list of ARNs that uniquely identify the Redis RDB snapshot files stored in S3		false	String
SnapshotRetentionLimit	The number of days for which ElastiCache retains automatic snapshots before deleting them		false	Integer
SnapshottingClusterId	The cluster ID used as the daily snapshot source for the replication group		false	String
NumNodeGroups	Specifies the number of node groups (shards) for this Redis replication group	1	false	Integer
ReplicasPerNodeGroup	An optional parameter that specifies the number of replica nodes in each node group (shard)	0	false	Integer	[0, 1, 2, 3, 4, 5]
NumCacheClusters	The number of clusters this replication group initially has	2	false	Integer	[1, 2, 3, 4, 5, 6]

Configuration

Redis Mode

Redis (Clustered Mode Enabled)

To create a replication group with Redis (Clustered Mode Enabled), you need to ensure these two configuration options are set.

cluster_enabled: true
automatic_failover: true

This is the default option

Redis (Clustered Mode Disabled)

To create a replication group with Redis (Clustered Mode Disabled), simply set the below configuration option. Automatic failover is optional for Redis (Clustered Mode Disabled), but defaults to on.

cluster_enabled: false

Replication Mode

There are two replication modes to choose from when creating Redis. The default mode uses node groups.

Node Groups

To explicitly set config to use node groups:

replication_mode:  node_group

This will then enable the following two parameters:

• NumNodeGroups Defaults to 1, but specifies the number of node groups (shards) for this Redis replication group.
• ReplicasPerNodeGroup Defaults to 0, that specifies the number of replica nodes in each node group (shard). Valid values are 0 to 5.

Cache Clusters

To explicitly set config to use cache clusters:

replication_mode:  cache_clusters

This will then enable the following parameter:

• NumCacheClusters Defaults to 2, The number of clusters this replication group initially has. Valid values are 1 to 6. If AutomaticFailoverEnabled is true, the value of this parameter must be at least 2.

Restoring from Snapshots

Native Snapshot Restore

To restore from a snapshot taken by the service, simply set the configuration below:

snapshot_restore_type: native

This will enable the below parameter:

• SnapshotName The name of a snapshot from which to restore data into the new replication group

S3 Snapshot Restore

To restore from RDB snapshot files stored in S3, set the configuration below:

snapshot_restore_type: s3

This will enable the below parameter:

• SnapshotArns A list of ARNs that uniquely identify the Redis RDB snapshot files stored in S3

Automatic Backups

By default, SnapshotRetentionLimit and SnapshottingClusterId are omitted from the CloudFormation resource, leaving any manually configured backup settings untouched.

To enable automatic backups via CloudFormation:

New clusters — set SnapshotRetentionLimit only. ElastiCache automatically assigns the primary node as the snapshotting cluster:

SnapshotRetentionLimit: 7

Existing clusters — both SnapshotRetentionLimit and SnapshottingClusterId are required when enabling backups on an existing cluster:

SnapshotRetentionLimit: 7
SnapshottingClusterId: my-cluster-001

Disable automatic backups:

SnapshotRetentionLimit: 0

Encryption Configuration

By default both encryption at rest and encryption in transit is ON by default. It will also use the default KMS key. You can use the below configuration to enable/disable either type of encryption. Be aware that modifying these values causes a replacement on the replication group.

at_rest_encryption: false
transit_encryption: false

If you wish to provide your own KMS key for encryption you can specify the ARN by setting the config below:

kms_key_id: arn:aws:kms:ap-southeast-2:111111111111:key/12345678-1234-1234-1234-111111111111