### Is there an existing issue for this?

[iambary44]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

When creating a new replication group in ElastiCache, localstack attempts to create redis instances in clustered mode.

awslocal elasticache create-replication-group \
  --replication-group-id my-redis-replication-group-2 \
  --replication-group-description 'my replication group' \
  --engine redis \
  --automatic-failover-enabled \
  --cache-node-type cache.t2.micro \
  --num-cache-clusters 2

This later leads to the following error when trying to connect to the cluster:

redis-cli -p 4513 set foo bar
(error) CLUSTERDOWN Hash slot not served

Moreover, this actually creates a redis cluster, so you can connect with redis-cli -c -p ... and run cluster nodes:

127.0.0.1:4510> cluster nodes
455c3afff747e81df15fed094ea5c2bcc1649d3c :4510@14510 myself,master - 0 0 1 connected 0-16383

Expected Behavior

This is not the behavior of AWS. In AWS, replication groups with one node group are by default in non-clustered mode, unless enabled explicitly. Instead of creating a cluster, the instances are managed via REPLICAOF

How are you starting LocalStack?

With a docker-compose file

Steps To Reproduce

How are you starting localstack (e.g., bin/localstack command, arguments, or docker-compose.yml)

LOCALSTACK_API_KEY=... localstack start

Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

See steps in description

Environment

- OS: Linux Mint 21.2
- LocalStack: latest

Anything else?

No response

Originally posted by @thrau in localstack/localstack#9317