terraform_required_providers.md

terraform_required_providers

Require that all providers specify a source and version constraint through required_providers.

This rule is enabled by "recommended" preset.

Configuration

rule "terraform_required_providers" {
  enabled = true

  # defaults
  source = true
  version = true
}

Examples

provider "template" {}

$ tflint
1 issue(s) found:

Warning: Missing version constraint for provider "template" in `required_providers` (terraform_required_providers)

  on main.tf line 1:
   1: provider "template" {}

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.1.0/docs/rules/terraform_required_providers.md

---

provider "template" {
  version = "2"
}

$ tflint
2 issue(s) found:

Warning: provider.template: version constraint should be specified via "required_providers" (terraform_required_providers)

  on main.tf line 1:
   1: provider "template" {

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.1.0/docs/rules/terraform_required_providers.md

Warning: Missing version constraint for provider "template" in `required_providers` (terraform_required_providers)

  on main.tf line 1:
   1: provider "template" {

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.1.0/docs/rules/terraform_required_providers.md

---

provider "template" {}

terraform {
  required_providers {
    template = {
      version = "~> 2"
    }
  }
}

$ tflint
1 issue(s) found:

Warning: Legacy version constraint for provider "template" in `required_providers` (terraform_required_providers)

  on main.tf line 5:
   5:     template = "~> 2"

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.1.0/docs/rules/terraform_required_providers.md

---

provider "template" {}

terraform {
  required_providers {
    template = {
      version = "~> 2"
    }
  }
}

$ tflint
1 issue(s) found:

Warning: Missing `source` for provider "template" in `required_providers` (terraform_required_providers)

  on main.tf line 5:
   5:     template = {
   6:       version = "~> 2"
   7:     }

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.1.0/docs/rules/terraform_required_providers.md

Why

Providers are plugins released on a separate rhythm from Terraform itself, and so they have their own version numbers. For production use, you should constrain the acceptable provider versions via configuration, to ensure that new versions with breaking changes will not be automatically installed by terraform init in future.

Terraform supports multiple provider registries/namespaces through the source address attribute. While this is optional for providers in registry.terraform.io under the hashicorp namespace (the defaults), it is required for all other providers. Omitting source is a common error when using third-party providers and using explicit source addresses for all providers is recommended.

How To Fix

Add the required_providers block to the terraform configuration block and include current versions for all providers. For example:

terraform {
  required_providers {
    template = {
      source  = "hashicorp/template"
      version = "~> 2"
    }
  }
}

Provider version constraints can be specified using a version argument within a provider block for backwards compatibility. This approach is now discouraged, particularly for child modules.

Optionally, you can disable enforcement of either source or version by setting the corresponding attribute in the rule configuration to false.