Scenario selection with tf

sample.tf

variable "scenario" {
  type = string
  description = "Scenario to deploy. Must be one of 'simple', or 'complex'."
  default = "simple"
  validation {
    condition = contains(["simple", "complex"], var.scenario)
    error_message = "Scenario must be one of 'simple', or 'complex'."
  }
}

variable "config_1" {
  type = string
  description = "Configuration 1"
  default = null
}

variable "config_2" {
  type = string
  description = "Configuration 2"
  default = null
}

variable "config_3" {
  type = string
  description = "Configuration 3"
  default = null
}

locals {
  scenarios = {
    simple = {
      config_1 = coalesce(var.config_1, "simple-config-1")
      config_2 = coalesce(var.config_2, "simple-config-2")
      config_3 = coalesce(var.config_3, "simple-config-3")
    }
    complex = {
      config_1 = coalesce(var.config_1, "complex-config-1")
      config_2 = coalesce(var.config_2, "complex-config-2")
      config_3 = coalesce(var.config_3, "complex-config-3")
    }
  }
}

resource "my_resource" "this" {
  config_1 = local.scenarios[var.scenario].config_1
  config_2 = local.scenarios[var.scenario].config_2
  config_3 = local.scenarios[var.scenario].config_3
}