In-place upgrade from ElastiCache Redis to Valkey cluster not working

[dheitepriem]

Describe the bug
The change of an existing ElastiCache ReplicationGroup from Redis to Valkey by an in-place upgrade using the elasticache-controller is not working

Steps to reproduce

• Create an ElastiCache for Redis cluster using this manifest:

apiVersion: elasticache.services.k8s.aws/v1alpha1
kind: ReplicationGroup
metadata:
  name: general-cluster
spec:
  atRestEncryptionEnabled: true
  automaticFailoverEnabled: true
  cacheNodeType: cache.t4g.small
  cacheParameterGroupName: default.redis7.cluster.on
  cacheSubnetGroupName: Subnet_Group_Name
  description: Redis cluster for general applications
  engine: redis
  multiAZEnabled: true
  numNodeGroups: 1
  preferredMaintenanceWindow: fri:00:00-fri:07:00
  replicasPerNodeGroup: 1
  replicationGroupID: general-cluster
  securityGroupIDs:
  - Security_Group_ID
  snapshotRetentionLimit: 0
  snapshotWindow: 23:00-00:00
  tags:
  - key: env
    value: dev
  - key: service
    value: core
  transitEncryptionEnabled: true
  userGroupIDs:
  - User_Group_ID

• Change the values of cacheParameterGroupName and engine

cacheParameterGroupName: default.redis7.cluster.on --> default.valkey8.cluster.on
engine: redis --> valkey

Expected outcome
The ElastiCache cluster is changed from Redis version 7 to Valkey version 8

Actual outcome
The ACK controller throws the error

  Conditions:
    Status:   True
    Type:     ACK.ResourceSynced
    Message:  InvalidParameterCombination: valkey parameter group is not applicable to engine redis
              status code: 400, request id: 2293b2a9-7938-473b-a530-ceed7a7d4074
    Status:   True
    Type:     ACK.Terminal

Environment

• ACK version ack-elasticache-controller.0.1.0
• Kubernetes version 1.32.0
• Using EKS (yes/no), if so version? Yes, eks.2
• AWS service targeted (S3, RDS, etc.) AWS ElastiCache