AWS::ElastiCache::ReplicationGroup - Sharded cluster always requires replacement when increasing number of nodes

[422158]

Name of the resource

Other

Resource name

AWS::ElastiCache::ReplicationGroup

Description

When you try to increase a number of nodes per shard in AWS::ElastiCache::ReplicationGroup, you always need to replace the resource. It does not matter whether I use ReplicasPerNodeGroup parameter or if I use NodeGroupConfiguration.

1. In case I use ReplicasPerNodeGroup, increase attempt always triggers the replacement.

2. In case I use NodeGroupConfiguration, increase attempt will throw error: Node Group with Id 0001 has replica count 3 (provided that the previous number of nodes in shard 0001 was 3)

Other Details

No response

[aaaeeeo]

+1 I can do this without replacement with ElastiCache directly: https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/increase-replica-count.html

[yb-yu]

I need this too. I added a new replica to failover on production, it became impossible to update cloudformation stack.

Is there any way to manually drift before aws supports it?

[ANILGIST]

• 1 waiting for this to be implemented. If we do the changes manually, then CFT would go out of sync.