2025-01-04-nested-backend-maps-support.mdx

slug	nested-backend-maps-support
title	Fixed: Nested Maps in Terraform Backend Configurations
authors	osterman
tags	bugfix
date	2025-01-04 00:00:00 UTC
release	v1.198.0

Atmos now properly handles nested maps in Terraform backend configurations when using HCL format. This fixes an issue where complex backend settings like assume_role were silently dropped.

The Problem

When generating backend configurations with atmos terraform generate backends --format hcl, nested maps were missing from the output. For example:

terraform:
  backend:
    s3:
      bucket: "my-terraform-states"
      assume_role:
        role_arn: "arn:aws:iam::123456789012:role/terraform"
        session_name: "terraform-backend"

The generated backend.tf was missing the assume_role configuration entirely.

The Fix

We added a recursive type converter that handles nested maps, arrays, and all Go types when generating HCL output. The JSON and backend-config formats already worked correctly.

Example

Now all nested configurations are properly preserved:

terraform {
  backend "s3" {
    bucket = "my-terraform-states"
    assume_role = {
      role_arn     = "arn:aws:iam::123456789012:role/terraform"
      session_name = "terraform-backend"
    }
  }
}

Usage

Upgrade Atmos and regenerate your backend configurations:

atmos terraform generate backends --format hcl

All three formats (HCL, JSON, backend-config) now correctly handle nested structures.