Why does terraform keeps updating parameter group of rds cluster?

Question

I am using terraform 0.13 and latest AWS provider version and it keeps updating aws_rds_cluster_parameter_group resource on each plan and apply. Any ideas why?

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  ~ update in-place
Terraform will perform the following actions:
  # aws_rds_cluster_parameter_group.data_db_parameters will be updated in-place
  ~ resource "aws_rds_cluster_parameter_group" "data_db_parameters" {
        arn         = "arn:aws:rds:ap-southeast-2:111111111111:cluster-pg:dev1-data-persistence-rds-pg"
        description = "Managed by Terraform"
        family      = "aurora-postgresql13"
        id          = "dev1-data-persistence-rds-pg"
        name        = "dev1-data-persistence-rds-pg"
        tags        = {}
        tags_all    = {}
        parameter {
            apply_method = "immediate"
            name         = "rds.force_ssl"
            value        = "1"
        }
      + parameter {
          + apply_method = "immediate"
          + name         = "ssl"
          + value        = "1"
        }
    }
Plan: 0 to add, 1 to change, 0 to destroy.

Answer 1

Those ghosts updates are a known, long standing issue, as evidenced by this still open, 3 year old issue on GH without a solution.

You can try updating your TF, as 0.13 is a very old version. You can also setup ignore_changes and try if this helps. If nothing works, then there is not much you can do about that. Its AWS provider and/or TF internal issue.