github.com/pdecat/terraform@v0.11.9-beta1/website/docs/configuration/terraform.html.md (about)

     1  ---
     2  layout: "docs"
     3  page_title: "Configuring Terraform"
     4  sidebar_current: "docs-config-terraform"
     5  description: |-
     6    The `terraform` configuration section is used to configure Terraform itself, such as requiring a minimum Terraform version to execute a configuration.
     7  ---
     8  
     9  # Terraform Configuration
    10  
    11  The `terraform` configuration section is used to configure Terraform itself,
    12  such as requiring a minimum Terraform version to execute a configuration.
    13  
    14  This page assumes you're familiar with the
    15  [configuration syntax](/docs/configuration/syntax.html)
    16  already.
    17  
    18  ## Example
    19  
    20  Terraform configuration looks like the following:
    21  
    22  ```hcl
    23  terraform {
    24    required_version = "> 0.7.0"
    25  }
    26  ```
    27  
    28  ## Description
    29  
    30  The `terraform` block configures the behavior of Terraform itself.
    31  
    32  The currently only allowed configurations within this block are
    33  `required_version` and `backend`.
    34  
    35  `required_version` specifies a set of version constraints
    36  that must be met to perform operations on this configuration. If the
    37  running Terraform version doesn't meet these constraints, an error
    38  is shown. See the section below dedicated to this option.
    39  
    40  See [backends](/docs/backends/index.html) for more detail on the `backend`
    41  configuration.
    42  
    43  **No value within the `terraform` block can use interpolations.** The
    44  `terraform` block is loaded very early in the execution of Terraform
    45  and interpolations are not yet available.
    46  
    47  ## Specifying a Required Terraform Version
    48  
    49  The `required_version` setting can be used to require a specific version
    50  of Terraform. If the running version of Terraform doesn't match the
    51  constraints specified, Terraform will show an error and exit.
    52  
    53  When [modules](/docs/configuration/modules.html) are used, all Terraform
    54  version requirements specified by the complete module tree must be
    55  satisified. This means that the `required_version` setting can be used
    56  by a module to require that all consumers of a module also use a specific
    57  version.
    58  
    59  The value of this configuration is a comma-separated list of constraints.
    60  A constraint is an operator followed by a version, such as `> 0.7.0`.
    61  Constraints support the following operations:
    62  
    63  - `=` (or no operator): exact version equality
    64  
    65  - `!=`: version not equal
    66  
    67  - `>`, `>=`, `<`, `<=`: version comparison, where "greater than" is a larger
    68    version number
    69  
    70  - `~>`: pessimistic constraint operator. Example: for `~> 0.9`, this means
    71    `>= 0.9, < 1.0`. Example: for `~> 0.8.4`, this means `>= 0.8.4, < 0.9`
    72  
    73  For modules, a minimum version is recommended, such as `> 0.8.0`. This
    74  minimum version ensures that a module operates as expected, but gives
    75  the consumer flexibility to use newer versions.
    76  
    77  ## Syntax
    78  
    79  The full syntax is:
    80  
    81  ```text
    82  terraform {
    83    required_version = VALUE
    84  }
    85  ```