supplying cluster_type to an aws_redshift_cluster resource can cause the resource to always be "changed" on subsequent apply operations

[ghost]

This issue was originally opened by @mmccord-mdbuyline as hashicorp/terraform#23660. It was migrated here as a result of the provider split. The original body of the issue is below.

---

@stack72 @bsiegel -- The change associated with this issue appears to have introduced a slight bug with the aws_redshift_cluster resource. If you create a cluster by supplying the resource with a cluster_type of single-node and number_of_nodes with 1 and then resize the cluster by supplying a cluster_type of multi-node and number_of_nodes with 2 then the resource will always be listed as "changed" in any subsequent apply operations.

In the plan output of any subsequent apply operations it will show cluster_type as changing from multi-node to multi-node and then try to execute a resize operation with the AWS API (which AWS will dutifully carry out even if the actual size of the cluster hasn't changed, thus taking the cluster down in the process). Re-worded: Essentially supplying a cluster_type in this way will continuously taint the cluster resource on apply.

The work around is to simply remove the supplied cluster_type entirely and allow it to be computed via number_of_nodes. I'm not sure what the suggested behavior here should be, but the current behavior is certainly surprising when you first encounter it. I was able to find the source issue fairly easily, but others may not be so lucky and resize operations do take down the cluster.

Whatever the code change is here I also suspect that some addition to the documentation is in order given that the below don't really fully explain the computed relationship.

number_of_nodes - (Optional) The number of compute nodes in the cluster. This parameter is required when the ClusterType parameter is specified as multi-node. Default is 1.

and

cluster_type - (Optional) The cluster type to use. Either single-node or multi-node.

documentation for convenience
original code change that seems to have caused the issue

[justinretzolk]

Hey @mmccord-mdbuyline 👋 Thank you for taking the time to file this issue! Given that there's been a number of AWS provider releases since you initially filed it, can you confirm whether you're still experiencing this behavior?

[ljluestc]

resource "aws_redshift_cluster" "example" {
  cluster_identifier = "example-cluster"
  node_type         = "dc2.large"  # Specify the desired node type
  number_of_nodes   = 2             # Set the desired number of nodes (for multi-node)

  # Omitting cluster_type to avoid tainting issues
  # cluster_type    = "multi-node"  # This line should be removed

  master_username   = "admin"
  master_password   = "yourpassword"  # Ensure this is secure
  db_name           = "mydatabase"
  skip_final_snapshot = true

  # Additional configuration as needed
}