Not able to reduce no. of shards after it is created

[not-ajay]

Description

Please provide a clear and concise description of the issue you are encountering, and a reproduction of your configuration (see the examples/* directory for references that you can copy+paste and tailor to match your configs if you are unable to copy your exact configuration). The reproduction MUST be executable by running terraform init && terraform apply without any further changes.

If your request is for a new feature, please use the Feature request template.

• ✋ I have searched the open/closed issues and my issue is not listed.

⚠️ Note

Before you submit an issue, please perform the following first:

1. Remove the local .terraform directory (! ONLY if state is stored remotely, which hopefully you are following that best practice!): rm -rf .terraform/
2. Re-initialize the project root to pull down modules: terraform init
3. Re-attempt your terraform plan or apply and check if the issue still persists

Versions

• Module version [Required]: Latest

• Terraform version: v1.13.3

• Provider version(s): hashicorp/aws v6.18.0

Reproduction Code [Required]

module "elasticache" {
  source                                  = "../../"
  replication_group_id                    = local.name
  create_primary_global_replication_group = true

  engine                     = "valkey"
  engine_version             = "7.2"
  node_type                  = "cache.r6g.large"
  snapshot_retention_limit   = 7
  port                       = 6399
  at_rest_encryption_enabled = true
  transit_encryption_enabled = true
  transit_encryption_mode    = "required"
  auth_token                 = "supersecure"
  auth_token_update_strategy = "SET"
  kms_key_arn                = "dummy-kms"
  cluster_mode               = "enabled"
  cluster_mode_enabled       = true
  multi_az_enabled           = true
  automatic_failover_enabled = true
  auto_minor_version_upgrade = false
  network_type               = "ipv4"
  num_node_groups            = 4
  replicas_per_node_group    = 2
  maintenance_window         = "fri:20:30-fri:21:30"
  snapshot_window            = "19:30-20:30"
  apply_immediately          = true
  vpc_id                     = data.terraform_remote_state.vpc.outputs.vpc_id
  subnet_ids                 = data.terraform_remote_state.vpc.outputs.subnets
  subnet_group_name          = local.name
  subnet_group_description   = "${title(local.name)} subnet group"
  create_security_group      = true
  security_group_rules = {
    ingress_vpc = {
      from_port      = 6399
      to_port        = 6399
      description    = "xxxx"
      prefix_list_id = "xxx"
    }
  }
  security_group_description  = "xxxx"
  security_group_tags         = merge({ "Name" = "${local.name}-sg" }, local.tags)
  create_parameter_group      = true
  parameter_group_name        = local.name
  parameter_group_family      = "valkey7"
  parameter_group_description = "${title(local.name)} parameter group"
  parameters = [
    {
      name  = "latency-tracking"
      value = "yes"
    }
  ]
  log_delivery_configuration = {
    slow-log = {
      destination_type = "cloudwatch-logs"
      log_format       = "json"
    }
  }
  tags = local.tags
}
module "elasticache_secondary" {
  source                                    = "../../"
  providers                                 = { aws = aws.secondary }
  create_secondary_global_replication_group = true
  global_replication_group_id               = module.elasticache.global_replication_group_id
  replication_group_id                      = local.name

  snapshot_retention_limit   = 7
  port                       = 6399
  auth_token                 = "supersecure"
  auth_token_update_strategy = "SET"
  kms_key_arn                = local.dr_kms_key
  cluster_mode               = "enabled"
  cluster_mode_enabled       = true
  multi_az_enabled           = true
  network_type               = "ipv4"
  num_node_groups            = 4
  replicas_per_node_group    = 2
  maintenance_window         = "fri:20:30-fri:21:30"
  snapshot_window            = "19:30-20:30"
  apply_immediately          = true
  vpc_id                     = data.vpc_secondary.outputs.vpc_id
  subnet_ids                 = data.vpc_secondary.outputs.dubnets
  subnet_group_name          = local.name
  subnet_group_description   = "${title(local.name)} subnet group"
  create_security_group      = true
  security_group_rules = {
    ingress_vpc = {
      from_port      = 6399
      to_port        = 6399
      description    = "xxxx"
      prefix_list_id = "xxxx"
    }
  }
  security_group_description  = "xxxx"
  security_group_tags         = merge({ "Name" = "${local.name}-sg" }, local.tags)
  create_parameter_group      = true
  parameter_group_name        = local.name
  parameter_group_family      = "valkey7"
  parameter_group_description = "${title(local.name)} parameter group"
  parameters = [
    {
      name  = "latency-tracking"
      value = "yes"
    }
  ]
  log_delivery_configuration = {
    slow-log = {
      destination_type = "cloudwatch-logs"
      log_format       = "json"
    }
  }
  tags = local.tags
}

Steps to reproduce the behavior:

yes create valkey global cluster in 2 regions with 4 shards(num_node_groups) and try to reduce the shards to 1 in above module "elasticache"

Expected behavior

no. of shards to be reduced from 4 to 1 in both clusters in each region

Actual behavior

Error: modifying ElastiCache Replication Group (abcd-valkey) shard configuration: operation error ElastiCache: ModifyReplicationGroupShardConfiguration, https response error StatusCode: 400, RequestID: , InvalidParameterValue: Cluster [abcd-valkey] is part of a global cluster [erpgt-abcd-valkey]. Request rejected.

Terminal Output Screenshot(s)

Additional context