Terraform variable inteporlation and evaluation

Question

I'm using the Yaml technique to manage variables when working with modules in Terraform. I have a very basic module that, based on the output from my RDS and IAM User modules, should construct a parameter in the AWS Parameter Store. I therefore created this module:

resource "aws_ssm_parameter" "ssm_parameter" {
  name      = var.parameter_name
  type      = var.parameter_type
  value     = var.parameter_value
  overwrite = var.overwrite
  tags      = var.tags
}

The variables I'm using are stored into a Yaml file like this:

ssms:
  /arquitetura/catalogo/gitlab/token:
    type: SecureString
    value: ManualInclude
  /arquitetura/catalogo/s3/access/key:
    type: String
    value: module.iam_user.access_key
  /arquitetura/catalogo/s3/secret/access/key:
    type: SecureString
    value: module.iam_user.secret_access_key
  /arquitetura/catalogo/rds/user:
    type: String
    value: module.rds_instance.database_username
  /arquitetura/catalogo/rds/password:
    type: SecureString
    value: module.rds_instance.database_password

As we can see, I have in "value" the module output I would like to send to Parameter Store. I'm loading this variable file using file and yamldecode functions:

  ssmfile                  = "./env/${terraform.workspace}/ssm.yaml"
  ssmfilecontent           = fileexists(local.ssmfile) ? file(local.ssmfile) : "ssmFileNotFound: true"
  ssmsettings              = yamldecode(local.ssmfilecontent)

So, I have a local.ssmsettings and I can write a module call like this:

module "ssm_parameter" {
  source = "../aws-ssm-parameter-tf"

  for_each = local.ssmsettings.ssms

  parameter_name  = each.key
  parameter_type  = each.value.type
  parameter_value = each.value.value
  tags            = local.tags
}

Doing this, my parameter is stored as:

{
    "Parameter": {
        "Name": "/arquitetura/catalogo/rds/user",
        "Type": "String",
        "Value": "module.rds_instance.database_username",
        "Version": 1,
        "LastModifiedDate": "2022-12-15T19:02:01.825000-03:00",
        "ARN": "arn:aws:ssm:sa-east-1:111111111111:parameter/arquitetura/catalogo/rds/user",
        "DataType": "text"
    }
}

Instead of the module output, the value is receiving the string module.rds instance. database username.

I am aware that Terraform does not have an eval function and that the file function does not interpolate variables.

Has anyone experienced this difficulty before and can share their solution with me? Do you have any pointers that I might use?

I've already made unsuccessful attempts to work with Terraform templates.

I appreciate it.