atmos-components

Atmos Component Architecture

Components are the building blocks of infrastructure in Atmos. Each component is an opinionated, reusable unit of infrastructure-as-code -- typically a Terraform root module -- that solves a specific problem. Atmos separates the component implementation (code) from its configuration (stack manifests), enabling one implementation to be deployed many times with different settings.

What Components Are

In Atmos, a component consists of two parts:

1. Implementation -- The infrastructure code itself (a Terraform root module, Helmfile, or Packer template) stored in the components/ directory.
2. Configuration -- The settings that customize how the component is deployed, defined in stack manifests under the components section.

This separation is fundamental: you write the Terraform module once, then configure it differently for each environment, region, and account through stack YAML files.

Component Types

Atmos natively supports three component types:

Type	Implementation Location	Purpose
Terraform / OpenTofu	components/terraform/<name>/	Provision cloud infrastructure resources
Helmfile	components/helmfile/<name>/	Deploy Helm charts to Kubernetes clusters
Packer	components/packer/<name>/	Build machine images (AMIs, VM images)

Terraform is by far the most common type. Custom commands can extend Atmos to support any tooling.

Directory Structure

Components are stored in your project's components/ directory, organized by type:

components/
  terraform/
    vpc/
      main.tf
      variables.tf
      outputs.tf
      versions.tf
    eks/
      cluster/
        main.tf
        variables.tf
        outputs.tf
    s3-bucket/
      main.tf
      variables.tf
      outputs.tf
    iam-role/
      main.tf
      variables.tf
      outputs.tf
  helmfile/
    nginx-ingress/
      helmfile.yaml
    cert-manager/
      helmfile.yaml
  packer/
    ubuntu-base/
      template.pkr.hcl