Terraform Block

The special terraform configuration block type is used to configure some behaviors of Terraform itself, such as requiring a minimum Terraform version to apply your configuration.

Each terraform block can contain a number of settings related to Terraform's behavior. Within a terraform block, only constant values can be used; arguments may not refer to named objects such as resources, input variables, etc, and may not use any of the Terraform language built-in functions.

Specifying a Required Terraform Version

The required_version setting can be used to constrain which versions of the Terraform CLI can be used with your configuration. If the running version of Terraform doesn't match the constraints specified, Terraform will produce an error and exit without taking any further actions.

The value for required_version is a string containing a comma-separated list of constraints. Each constraint is an operator followed by a version number, such as > 0.12.0. The following constraint operators are allowed:

  • = (or no operator): exact version equality
  • !=: version not equal
  • >, >=, <, <=: version comparison, where "greater than" is a larger version number
  • ~>: pessimistic constraint operator, constraining both the oldest and newest version allowed. For example, ~> 0.9 is equivalent to >= 0.9, < 1.0, and ~> 0.8.4, is equivalent to >= 0.8.4, < 0.9

Specifying Required Provider Versions

The required_providers setting is a map specifying a version constraint for each provider required by your configuration.

This is one of several ways to define provider version constraints and is particularly suited to re-usable modules that expect a provider configuration to be provided by their caller but still need to impose a minimum version for that provider.

let's use terraform block in our code. create a new file named terraform.tf with the below content

terraform {
  required_version = "1.1.0"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "3.71.0"

we can also specify backend in terraform block that we will use in future blogs.