Native Terraform Migration Example

This example demonstrates migrating from native Terraform (with .tfvars files) to Atmos.

Overview

The example shows two migration strategies side by side:

Stack	File	Strategy	Stack Name
dev	stacks/dev.yaml	Keep existing .tfvars via !include	dev (from filename)
prod	stacks/prod.yaml	Convert to native YAML	production (explicit name)

Directory Structure

├── atmos.yaml                        # Atmos configuration
├── components/terraform/vpc/         # Your Terraform root module
│   ├── main.tf
│   ├── variables.tf
│   ├── outputs.tf
│   └── envs/                         # Existing .tfvars files
│       ├── dev.tfvars
│       └── prod.tfvars
└── stacks/
    ├── _defaults.yaml                # Shared defaults (imported by both stacks)
    ├── dev.yaml                      # Uses !include for existing tfvars
    └── prod.yaml                     # Fully converted to YAML

Key Concepts

!include for .tfvars

The dev stack uses !include to import existing .tfvars files directly:

components:
  terraform:
    vpc:
      vars: !include ../components/terraform/vpc/envs/dev.tfvars

This is the fastest migration path — your existing variable files keep working.

Stack Names

The prod stack uses an explicit name field to override the filename:

name: production

This means you reference it as atmos terraform plan vpc -s production, not -s prod.

Imports

Both stacks import shared defaults from _defaults.yaml:

import:
  - _defaults

Usage

# List all stacks
atmos list stacks

# Dev stack (uses !include for tfvars)
atmos terraform plan vpc -s dev
atmos describe component vpc -s dev

# Prod stack (explicit name, converted to YAML)
atmos terraform plan vpc -s production
atmos describe component vpc -s production

# This will NOT work (filename is not the canonical name):
# atmos terraform plan vpc -s prod