Terraform 0.13 Variable Validation Rule

main.tf

terraform {
  required_version = "~> 0.13.0"
}

variable "environment_name" {
  description = "The environment name."
  type        = string

  validation {
    condition     = contains(["develop", "stage", "production"], var.environment_name)
    error_message = "The environment_name value is not allowed. [\"develop\", \"stage\", \"production\"]."
  }
}

# Notes:
# `condition` The condition for variable "environment_name" can only refer to the variable itself, using var.environment_name.
# `error_message` Validation error message must be at least one full English sentence starting with an uppercase letter and ending with a period or question mark.