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Configure Dependencies

The dependencies section defines tool version requirements. Tool dependencies ensure your components use the correct versions of CLI tools like Terraform, kubectl, or helm.

Use Cases​

  • Tool Version Requirements: Ensure components use specific Terraform, kubectl, or helm versions
  • Team Consistency: Version-control tool requirements for reproducible deployments
  • CI/CD Reliability: Guarantee correct tool versions in automated pipelines

Tool Dependencies​

The dependencies.tools section declares which CLI tool versions a component requires. Atmos automatically installs and uses the specified versions when executing the component.

Configuration Scopes​

Tool dependencies can be defined at multiple levels, with more specific levels taking precedence.

Global Level​

Tool versions defined at the root level apply to all components:

stacks/orgs/acme/_defaults.yaml

# Global tool dependencies
dependencies:
  tools:
    terraform: "1.9.8"      # All Terraform components use this version
    kubectl: "1.28.0"        # All kubectl commands use this version

Component-Type Level​

Tool versions defined under terraform, helmfile, or packer apply to all components of that type:

stacks/orgs/acme/plat/prod/_defaults.yaml

terraform:
  dependencies:
    tools:
      terraform: "1.9.8"     # All Terraform components use 1.9.8
      tflint: "0.44.1"       # All Terraform components use tflint 0.44.1

helmfile:
  dependencies:
    tools:
      helm: "3.13.0"         # All Helmfile releases use helm 3.13.0
      kubectl: "1.28.0"      # All Helmfile releases use kubectl 1.28.0

Component Level​

Tool versions defined within a component override all higher-level settings:

stacks/orgs/acme/plat/prod/us-east-1.yaml

components:
  terraform:
    vpc:
      dependencies:
        tools:
          terraform: "1.8.5"   # This component uses older Terraform version
          aws-cli: "2.13.0"    # Component-specific AWS CLI version

Version Resolution​

Tool dependencies support multiple version formats:

Exact version

Use a specific version: "1.9.8"

Latest version

Use the latest available version: "latest"

Semver constraint (planned)

Use semantic version ranges: ">=1.8.0", "~>1.9.0"

Inheritance and Merge Behavior​

Tool dependencies are merged from the most general to the most specific level:

  1. Global dependencies.tools (applies to all components)
  2. Component-type terraform.dependencies.tools (applies to all components of that type)
  3. Component components.terraform.<name>.dependencies.tools (applies to specific component)

More specific levels override less specific levels. For example:

Example: Version Override

# Global default
dependencies:
  tools:
    terraform: "1.9.8"

# Component-type override
terraform:
  dependencies:
    tools:
      terraform: "1.9.8"
      tflint: "0.44.1"     # Added for all Terraform components

# Component-specific override
components:
  terraform:
    legacy-vpc:
      dependencies:
        tools:
          terraform: "1.5.0"  # This component uses older version
          tflint: "0.44.1"    # Inherited from component-type level

Result:

  • Most Terraform components use Terraform 1.9.8
  • legacy-vpc component uses Terraform 1.5.0
  • All Terraform components use tflint 0.44.1

Integration with Toolchain​

Tool dependencies integrate seamlessly with the toolchain management system:

  1. Automatic Installation: When you run a component, Atmos installs the required tool versions automatically
  2. Version Isolation: Each component uses its declared versions, isolated from other components
  3. Cache Efficiency: Tools are cached and reused across components with the same version requirements

Example workflow:

# Component declares terraform: "1.9.8"
atmos terraform plan vpc -s prod

# Atmos automatically:
# 1. Checks if terraform 1.9.8 is installed
# 2. Installs it if missing (from toolchain registries)
# 3. Executes: terraform plan (using 1.9.8)

Complete Tool Dependencies Example​

stacks/orgs/acme/plat/prod/us-east-1.yaml

# Global tool dependencies (all components)
dependencies:
  tools:
    terraform: "1.9.8"
    kubectl: "1.28.0"

# Component-type dependencies (all Terraform components)
terraform:
  dependencies:
    tools:
      terraform: "1.9.8"      # Override global if needed
      tflint: "0.44.1"        # Terraform-specific tool
      tfsec: "1.28.0"         # Security scanning
      aws-cli: "latest"       # Use latest AWS CLI

# Component-type dependencies (all Helmfile releases)
helmfile:
  dependencies:
    tools:
      helm: "3.13.0"
      kubectl: "1.28.0"
      helmfile: "0.157.0"

# Component-specific dependencies
components:
  terraform:
    vpc:
      dependencies:
        tools:
          terraform: "1.9.8"    # Use default
          aws-cli: "2.13.0"     # Component needs specific AWS CLI version

    legacy-app:
      dependencies:
        tools:
          terraform: "1.5.0"    # Legacy component requires older version
          aws-cli: "2.10.0"

  helmfile:
    monitoring:
      dependencies:
        tools:
          helm: "3.13.0"
          kubectl: "1.28.0"

Component Dependencies​

Looking for Component Dependencies?

The dependencies section currently supports tool dependencies only. For component execution order and cross-component dependencies, use settings.depends_on. We plan to consolidate these features in a future release.

Best Practices​

  1. Pin Versions Explicitly - Use exact versions ("1.9.8") instead of "latest" for production
  2. Consistent Team Standards - Define global defaults in _defaults.yaml files
  3. Component-Specific Overrides - Only override when necessary (legacy code, compatibility)
  4. Document Reasons - Add comments explaining why a component uses a different version
  5. Test Before Upgrading - Test tool version changes in dev/staging before production