How would you define a variable in a Terraform configuration file?

In Terraform, defining a variable involves using the variable block, which explicitly declares the variable name and its attributes in the configuration file. This syntax allows you to define variables with specific characteristics, such as type, description, and default values, which enhances the modularity and reusability of your configuration.

For example, a typical variable declaration in a .tf file looks like this:

variable "instance_type" {

description = "The type of instance to create"

type        = string

default     = "t2.micro"

}

This structure clearly communicates the intention behind the variable and allows Terraform to validate inputs based on the specified type. It also facilitates the automatic handling of default values, making your configurations more robust and user-friendly.

Creating a separate .tf variable file might be used for organizing multiple variables but does not define a variable by itself. Specifying a variable solely in the main configuration file can limit clarity and structure. Lastly, while environment variables can be utilized to pass variable values, they do not define the variable itself within the Terraform configuration, which is why the proper method is to use the variable block.