Redis Multi-AZ feature in CloudFormation - amazon-web-services

Question

I'm designing a template which includes a Redis service and I would like to enable Multi-AZ feature in Redis such that upon the primary cluster failure, read replica can be promoted to primary. I looked in the CloudFormation documentation but I couldn't find this feature i.e. Multi-AZ. It is available for RDS service but not for Redis. Can I know how I can include the feature for redis such AWS take cares of the automatic failover ?
Source:
http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-elasticache-cache-cluster.html
The list of properties that are available for the elastic cache are listed below.
"AutoMinorVersionUpgrade" : Boolean,
"AZMode" : String,
"CacheNodeType" : String,
"CacheParameterGroupName" : String,
"CacheSecurityGroupNames" : [ String, ... ],
"CacheSubnetGroupName" : String,
"ClusterName" : String,
"Engine" : String,
"EngineVersion" : String,
"NotificationTopicArn" : String,
"Port" : Integer,
"PreferredAvailabilityZone" : String,
"PreferredAvailabilityZones" : [String, ... ],
"PreferredMaintenanceWindow" : String,
"SnapshotArns" : [String, ... ],
"SnapshotName" : String,
"SnapshotRetentionLimit" : Integer,
"SnapshotWindow" : String,
"Tags" : [Resource Tag, ...],
"VpcSecurityGroupIds" : [String, ...]

Answer 1

This are the two ways you can set Redis to use Multi Az programatically.
Using CLI
aws elasticache modify-replication-group \
--replication-group-id myReplGroup \
--automatic-failover-enabled
Using Elasticache API
https://elasticache.us-west-2.amazonaws.com/
?Action=ModifyReplicationGroup
&AutoFailover=true
&ReplicationGroupId=myReplGroup
&Version=2015-02-02
&SignatureVersion=4
&SignatureMethod=HmacSHA256
&Timestamp=20140401T192317Z
&X-Amz-Credential=<credential>
This are some of the notes that you should read while selecting Multi Az for redis.
http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/AutoFailover.html#AutoFailover.Notes
For Cloud Formation below are the Properties:
{
"Type" : "AWS::ElastiCache::ReplicationGroup",
"Properties" : {
"AutomaticFailoverEnabled" : Boolean,
"AutoMinorVersionUpgrade" : Boolean,
"CacheNodeType" : String,
"CacheParameterGroupName" : String,
"CacheSecurityGroupNames" : [ String, ... ],
"CacheSubnetGroupName" : String,
"Engine" : String,
"EngineVersion" : String,
"NotificationTopicArn" : String,
"NumCacheClusters" : Integer,
"Port" : Integer,
"PreferredCacheClusterAZs" : [ String, ... ],
"PreferredMaintenanceWindow" : String,
"ReplicationGroupDescription" : String,
"SecurityGroupIds" : [ String, ... ],
"SnapshotArns" : [ String, ... ],
"SnapshotRetentionLimit" : Integer,
"SnapshotWindow" : String
}
}
You have to tweak this property for Multi Az
AutomaticFailoverEnabled
Indicates whether Multi-AZ is enabled. When Multi-AZ is enabled, a read-only replica is automatically promoted to a read-write primary cluster if the existing primary cluster fails. If you specify true, you must specify a value greater than 1 for the NumCacheNodes property. By default, AWS CloudFormation sets the value to true.
For more information about Multi-AZ, see Multi-AZ with Redis Replication Groups in the Amazon ElastiCache User Guide.
Note
You cannot enable automatic failover for Redis versions earlier than 2.8.6 or for T1 and T2 cache node types.
Required: No
Type: Boolean
http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-elasticache-replicationgroup.html