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Pin Terraform and Provider Versions in Stack Configuration

· 2 min read
Erik Osterman
Erik Osterman
Founder @ Cloud Posse

You can now pin Terraform and provider versions directly in your stack configuration. Atmos generates terraform_override.tf.json files with required_version and required_providers blocks, giving you centralized control over infrastructure versioning.

What Changed​

Previously, pinning Terraform and provider versions required modifying component source code or maintaining separate override files. Now you can declare versions in your stack YAML:

components:
  terraform:
    vpc:
      metadata:
        component: vpc
      vars:
        name: main-vpc
      terraform:
        required_version: ">= 1.10.1"
        required_providers:
          aws:
            source: "hashicorp/aws"
            version: "~> 5.0"
          random:
            source: "hashicorp/random"
            version: ">= 3.0"

How It Works​

When you run atmos terraform generate required-providers, Atmos creates a terraform_override.tf.json file in your component directory:

{
  "terraform": {
    "required_version": ">= 1.10.1",
    "required_providers": {
      "aws": {
        "source": "hashicorp/aws",
        "version": "~> 5.0"
      },
      "random": {
        "source": "hashicorp/random",
        "version": ">= 3.0"
      }
    }
  }
}

This override file merges with your component's existing Terraform configuration, allowing you to pin versions without modifying component source code.

Stack Inheritance​

Version constraints follow Atmos's standard inheritance model. Define base versions in a catalog and override per-environment:

# stacks/catalog/terraform.yaml
terraform:
  required_version: ">= 1.9.0"
  required_providers:
    aws:
      source: "hashicorp/aws"
      version: "~> 5.0"

# stacks/deploy/prod.yaml
import:
  - catalog/terraform

terraform:
  required_version: ">= 1.10.1"  # Override for prod

CLI Usage​

Generate the override file for a specific component and stack:

atmos terraform generate required-providers vpc --stack dev-us-east-1

Or specify a custom output path:

atmos terraform generate required-providers vpc --stack dev-us-east-1 \
  --file /custom/path/terraform_override.tf.json

Why This Matters​

  • Centralized version management - Control versions across all components from stack configuration
  • Environment-specific versions - Pin stricter versions in production while allowing flexibility in development
  • No component modification - Override files work without changing component source code
  • Inheritance support - Define base versions in catalogs and override where needed