terraform/website/docs/language/settings/index.html.md

---
layout: "language"
page_title: "Terraform Settings - Configuration Language"
sidebar_current: "docs-config-terraform"
description: |-
  The "terraform" configuration section is used to configure some behaviors
  of Terraform itself.
---

# Terraform Settings

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.

## Terraform Block Syntax

Terraform settings are gathered together into `terraform` blocks:

```hcl
terraform {
  # ...
}
```

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.

The various options supported within a `terraform` block are described in the
following sections.

## Configuring a Terraform Backend

The nested `backend` block configures which backend Terraform should use.

The syntax and behavior of the `backend` block is described in [Backend
Configuration](/docs/language/settings/backends/configuration.html).

## Specifying a Required Terraform Version

The `required_version` setting accepts a [version constraint
string,](/docs/language/expressions/version-constraints.html) which specifies which versions of Terraform
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.

When you use [child modules](/docs/language/modules/index.html), each module can specify its own
version requirements. The requirements of all modules in the tree must be
satisfied.

Use Terraform version constraints in a collaborative environment to
ensure that everyone is using a specific Terraform version, or using at least
a minimum Terraform version that has behavior expected by the configuration.

The `required_version` setting applies only to the version of Terraform CLI.
Terraform's resource types are implemented by provider plugins,
whose release cycles are independent of Terraform CLI and of each other.
Use [the `required_providers` block](/docs/language/providers/requirements.html) to manage
the expected versions for each provider you use.

## Specifying Provider Requirements

[inpage-source]: #specifying-provider-requirements

The `required_providers` block specifies all of the providers required by the
current module, mapping each local provider name to a source address and a
version constraint.

```hcl
terraform {
  required_providers {
    aws = {
      version = ">= 2.7.0"
      source = "hashicorp/aws"
    }
  }
}
```

For more information, see [Provider Requirements](/docs/language/providers/requirements.html).

## Experimental Language Features

The Terraform team will sometimes introduce new language features initially via
an opt-in experiment, so that the community can try the new feature and give
feedback on it prior to it becoming a backward-compatibility constraint.

In releases where experimental features are available, you can enable them on
a per-module basis by setting the `experiments` argument inside a `terraform`
block:

```hcl
terraform {
  experiments = [example]
}
```

The above would opt in to an experiment named `example`, assuming such an
experiment were available in the current Terraform version.

Experiments are subject to arbitrary changes in later releases and, depending on
the outcome of the experiment, may change drastically before final release or
may not be released in stable form at all. Such breaking changes may appear
even in minor and patch releases. We do not recommend using experimental
features in Terraform modules intended for production use.

In order to make that explicit and to avoid module callers inadvertently
depending on an experimental feature, any module with experiments enabled will
generate a warning on every `terraform plan` or `terraform apply`. If you
want to try experimental features in a shared module, we recommend enabling the
experiment only in alpha or beta releases of the module.

The introduction and completion of experiments is reported in
[Terraform's changelog](https://github.com/hashicorp/terraform/blob/master/CHANGELOG.md),
so you can watch the release notes there to discover which experiment keywords,
if any, are available in a particular Terraform release.

## Passing Metadata to Providers

The `terraform` block can have a nested `provider_meta` block for each
provider a module is using, if the provider defines a schema for it. This
allows the provider to receive module-specific information, and is primarily
intended for modules distributed by the same vendor as the associated provider.

For more information, see [Provider Metadata](/docs/internals/provider-meta.html).