github.com/hugorut/terraform@v1.1.3/website/docs/language/expressions/version-constraints.mdx (about)

     1  ---
     2  page_title: Version Constraints - Configuration Language
     3  description: >-
     4    Version constraint strings specify a range of acceptable versions for modules,
     5    providers, and Terraform itself. Learn version constraint syntax and behavior.
     6  ---
     7  
     8  # Version Constraints
     9  
    10  Anywhere that Terraform lets you specify a range of acceptable versions for
    11  something, it expects a specially formatted string known as a version
    12  constraint. Version constraints are used when configuring:
    13  
    14  - [Modules](/language/modules)
    15  - [Provider requirements](/language/providers/requirements)
    16  - [The `required_version` setting](/language/settings#specifying-a-required-terraform-version) in the `terraform` block.
    17  
    18  ## Version Constraint Syntax
    19  
    20  Terraform's syntax for version constraints is very similar to the syntax used by
    21  other dependency management systems like Bundler and NPM.
    22  
    23  ```hcl
    24  version = ">= 1.2.0, < 2.0.0"
    25  ```
    26  
    27  A version constraint is a [string literal](/language/expressions/strings)
    28  containing one or more conditions, which are separated by commas.
    29  
    30  Each condition consists of an operator and a version number.
    31  
    32  Version numbers should be a series of numbers separated by periods (like
    33  `1.2.0`), optionally with a suffix to indicate a beta release.
    34  
    35  The following operators are valid:
    36  
    37  - `=` (or no operator): Allows only one exact version number. Cannot be combined
    38    with other conditions.
    39  
    40  - `!=`: Excludes an exact version number.
    41  
    42  - `>`, `>=`, `<`, `<=`: Comparisons against a specified version, allowing
    43    versions for which the comparison is true. "Greater-than" requests newer
    44    versions, and "less-than" requests older versions.
    45  
    46  - `~>`: Allows only the _rightmost_ version component to increment. For example,
    47    to allow new patch releases within a specific minor release, use the full
    48    version number: `~> 1.0.4` will allow installation of `1.0.5` and `1.0.10`
    49    but not `1.1.0`. This is usually called the pessimistic constraint operator.
    50  
    51  ## Version Constraint Behavior
    52  
    53  A version number that meets every applicable constraint is considered acceptable.
    54  
    55  Terraform consults version constraints to determine whether it has acceptable
    56  versions of itself, any required provider plugins, and any required modules. For
    57  plugins and modules, it will use the newest installed version that meets the
    58  applicable constraints.
    59  
    60  If Terraform doesn't have an acceptable version of a required plugin or module,
    61  it will attempt to download the newest version that meets the applicable
    62  constraints.
    63  
    64  If Terraform isn't able to obtain acceptable versions of external dependencies,
    65  or if it doesn't have an acceptable version of itself, it won't proceed with any
    66  plans, applies, or state manipulation actions.
    67  
    68  Both the root module and any child module can constrain the acceptable versions
    69  of Terraform and any providers they use. Terraform considers these constraints
    70  equal, and will only proceed if all of them can be met.
    71  
    72  A prerelease version is a version number that contains a suffix introduced by
    73  a dash, like `1.2.0-beta`. A prerelease version can be selected only by an
    74  _exact_ version constraint (the `=` operator or no operator). Prerelease
    75  versions do not match inexact operators such as `>=`, `~>`, etc.
    76  
    77  ## Best Practices
    78  
    79  ### Module Versions
    80  
    81  - When depending on third-party modules, require specific versions to ensure
    82    that updates only happen when convenient to you.
    83  
    84  - For modules maintained within your organization, specifying version ranges
    85    may be appropriate if semantic versioning is used consistently or if there is
    86    a well-defined release process that avoids unwanted updates.
    87  
    88  ### Terraform Core and Provider Versions
    89  
    90  - Reusable modules should constrain only their minimum allowed versions of
    91    Terraform and providers, such as `>= 0.12.0`. This helps avoid known
    92    incompatibilities, while allowing the user of the module flexibility to
    93    upgrade to newer versions of Terraform without altering the module.
    94  
    95  - Root modules should use a `~>` constraint to set both a lower and upper bound
    96    on versions for each provider they depend on.