Terraform 0.13 does not support optional keyword

[KevinSnyderCodes]

https://github.com/rancherfederal/rke2-aws-tf/blob/v2.4.2/modules/agent-nodepool/variables.tf#L77C1-L94C2

variable "asg" {
  description = "Node pool AutoScalingGroup scaling definition"
  type = object({
    min                  = number
    max                  = number
    desired              = number
    suspended_processes  = optional(list(string))
    termination_policies = optional(list(string))
  })

  default = {
    min                  = 1
    max                  = 10
    desired              = 1
    suspended_processes  = []
    termination_policies = ["Default"]
  }
}

https://github.com/rancherfederal/rke2-aws-tf/blob/v2.4.2/modules/agent-nodepool/versions.tf

terraform {
  required_version = ">= 0.13"
}

~ terraform --version

Terraform v0.13.0

~ cd modules/agent_nodepool && terraform init

There are some problems with the configuration, described below.

The Terraform configuration must be valid before initialization so that
Terraform can determine which modules and providers need to be installed.

Error: Invalid type specification

  on variables.tf line 83, in variable "asg":
  83:     suspended_processes  = optional(list(string))

Keyword "optional" is not a valid type constructor.


Error: Invalid type specification

  on variables.tf line 84, in variable "asg":
  84:     termination_policies = optional(list(string))

Keyword "optional" is not a valid type constructor.

According to the Terraform changelog, the optional keyword was added as an experiment in Terraform 0.14 and made official in Terraform 1.3.

Solution: Remove the optional keyword, OR bump the required Terraform version to >= 1.3.

This affects v2.4.2, the latest version of this module.

[adamacosta]

We'll have to bump the required Terraform version. I think the only other way to add the suspended processes and termination policies without breaking any current deployments not setting those is to make the type constraint any, but if you use any, you can't set a default value without creating an implicit type constraint.

[adamacosta]

Fixed by #102