---
title: "Terragrunt Generator"
description: "Generate production-ready Terragrunt configurations following current best practices, naming conventions, and security standards. All generated configurations are automatically validated."
type: skill
canonical_url: https://claudary.paisolsolutions.com/skills/skill-110
source: "Claudary"
difficulty: intermediate
author: "Claude Code Knowledge Pack"
date: 2026-07-10T11:47:08.619Z
license: CC-BY-4.0
attribution: "Terragrunt Generator — Claudary (https://claudary.paisolsolutions.com/skills/skill-110)"
---

# Terragrunt Generator
Generate production-ready Terragrunt configurations following current best practices, naming conventions, and security standards. All generated configurations are automatically validated.

## Overview

---
name: terragrunt-generator
description: Generate/create/scaffold Terragrunt HCL files — root.hcl, terragrunt.hcl, child modules, stacks, multi-env layouts.
---

# Terragrunt Generator

## Overview

Generate production-ready Terragrunt configurations following current best practices, naming conventions, and security standards. All generated configurations are automatically validated.

## Trigger Phrases

Use this skill when the user asks for:
- A new `root.hcl`, `terragrunt.hcl`, or `terragrunt.stack.hcl`
- Multi-environment Terragrunt layouts (`dev/staging/prod`)
- Terragrunt dependency wiring (`dependency` or `dependencies` blocks)
- Terragrunt module source setup (local, Git, Terraform Registry via `tfr:///`)
- Stack catalog unit generation under `catalog/units/*`

**Terragrunt 2025 Features Supported:**
- [Stacks](https://terragrunt.gruntwork.io/docs/features/stacks/) - Infrastructure blueprints with `terragrunt.stack.hcl` (GA since v0.78.0)
- [Feature Flags](https://terragrunt.gruntwork.io/docs/features/feature-flags/) - Runtime control via `feature` blocks
- [Exclude Blocks](https://terragrunt.gruntwork.io/docs/reference/config-blocks-and-attributes/#exclude) - Fine-grained execution control (replaces deprecated `skip`)
- [Errors Blocks](https://terragrunt.gruntwork.io/docs/reference/config-blocks-and-attributes/#errors) - Advanced error handling (replaces deprecated `retryable_errors`)
- [OpenTofu Engine](https://terragrunt.gruntwork.io/docs/features/engine/) - Alternative IaC engine support

## Root Configuration Naming

> **RECOMMENDED**: Use `root.hcl` instead of `terragrunt.hcl` for root files per [migration guide](https://terragrunt.gruntwork.io/docs/migrate/migrating-from-root-terragrunt-hcl).

| Approach | Root File | Include Syntax |
|----------|-----------|----------------|
| **Modern** | `root.hcl` | `find_in_parent_folders("root.hcl")` |
| **Legacy** | `terragrunt.hcl` | `find_in_parent_folders()` |

**Include standard:** Default to `find_in_parent_folders("root.hcl")` in all new examples and generated configs. Use `find_in_parent_folders()` only when explicitly targeting a legacy root file named `terragrunt.hcl`.

## Architecture Patterns

> **CRITICAL:** Before generating ANY configuration, you MUST determine the architecture pattern and understand its constraints.

### Pattern A: Multi-Environment with Environment-Agnostic Root

**Use when:** Managing multiple environments (dev/staging/prod) with shared root configuration.

**Key principle:** `root.hcl` is **environment-agnostic** - it does NOT read environment-specific files.

```
infrastructure/
├── root.hcl              # Environment-AGNOSTIC (no env.hcl references)
├── dev/
│   ├── env.hcl           # Environment variables (locals block)
│   ├── vpc/terragrunt.hcl
│   └── rds/terragrunt.hcl
└── prod/
    ├── env.hcl           # Environment variables (locals block)
    ├── vpc/terragrunt.hcl
    └── rds/terragrunt.hcl
```

**Root.hcl constraints:**
- ❌ CANNOT use `read_terragrunt_config(find_in_parent_folders("env.hcl"))` - env.hcl doesn't exist at root level
- ❌ CANNOT reference `local.environment` or `local.aws_region` that come from env.hcl
- ✅ CAN use static values or `get_env()` for runtime configuration
- ✅ CAN use `${path_relative_to_include()}` for state keys (this works dynamically)

**Child modules read env.hcl:**
```hcl
# dev/vpc/terragrunt.hcl
include "root" {
  path = find_in_parent_folders("root.hcl")
}

locals {
  env = read_terragrunt_config(find_in_parent_folders("env.hcl"))
}

inputs = {
  name = "${local.env.locals.environment}-vpc"  # Works: env.hcl exists in dev/
}
```

### Pattern B: Single Environment or Environment-Aware Root

**Use when:** Single environment OR all environments share the same root with environment detection.

```
infrastructure/
├── root.hcl              # Can be environment-aware via get_env() or directory parsing
├── account.hcl           # Account-level config (optional)
├── region.hcl            # Region-level config (optional)
└── vpc/
    └── terragrunt.hcl
```

**Root.hcl can detect environment:**
```hcl
# root.hcl - environment detection via directory path
locals {
  # Parse environment from path (e.g., "prod/vpc" -> "prod")
  path_parts  = split("/", path_relative_to_include())
  environment = local.path_parts[0]

  # OR use environment variable
  environment = get_env("TG_ENVIRONMENT", "dev")
}
```

### Pattern C: Shared Environment Variables (_env directory)

**Use when:** Centralizing environment variables with symlinks or direct references.

```
infrastructure/
├── root.hcl              # Environment-AGNOSTIC
├── _env/                 # Centralized environment definitions
│   ├── prod.hcl
│   ├── staging.hcl
│   └── dev.hcl
├── prod/
│   ├── env.hcl           # Reads from _env/prod.hcl
│   └── vpc/terragrunt.hcl
└── dev/
    ├── env.hcl           # Reads from _env/dev.hcl
    └── vpc/terragrunt.hcl
```

**env.hcl reads from _env:**
```hcl
# prod/env.hcl
locals {
  env_vars = read_terragrunt_config("${get_repo_root()}/_env/prod.hcl")

  # Re-export for child modules
  environment        = local.env_vars.locals.environment
  aws_region         = local.env_vars.locals.aws_region
  vpc_cidr           = local.env_vars.locals.vpc_cidr
  # ... other variables
}
```

### Architecture Pattern Selection Checklist (Canonical)

> **MANDATORY:** Before writing any files, you MUST complete this checklist and OUTPUT it to the user with checkmarks filled in. This is not optional.

**Output this completed checklist before generating any files:**
```
## Architecture Pattern Selection

[x] Identified architecture pattern: Pattern ___ (A/B/C)
[x] Root.hcl scope: [ ] environment-agnostic  OR  [ ] environment-aware
[x] env.hcl location: ___________________
[x] Child modules access env via: ___________________
[x] Verified: No file references a path that doesn't exist from its location
```

**Example completed checklist:**
```
## Architecture Pattern Selection

[x] Identified architecture pattern: Pattern A (Multi-Environment with Environment-Agnostic Root)
[x] Root.hcl scope: [x] environment-agnostic  OR  [ ] environment-aware
[x] env.hcl location: dev/env.hcl, prod/env.hcl (one per environment)
[x] Child modules access env via: read_terragrunt_config(find_in_parent_folders("env.hcl"))
[x] Verified: No file references a path that doesn't exist from its location
```

## Quick Variable Definition Examples

Use these starter files for Pattern B and account/region-aware setups.

**env.hcl**
```hcl
locals {
  environment = "dev"
  aws_region  = "us-east-1"
  project     = "platform"
}
```

**account.hcl**
```hcl
locals {
  account_id   = "123456789012"
  account_name = "shared-services"
}
```

**region.hcl**
```hcl
locals {
  aws_region = "us-east-1"
}
```

## When to Use

- Creating new Terragrunt projects or configurations
- Setting up multi-environment infrastructure (dev/staging/prod)
- Implementing DRY Terraform configurations
- Managing complex infrastructure with dependencies
- Working with custom Terraform providers or modules

## Core Capabilities

### 1. Generate Root Configuration
Create root-level `root.hcl` or `terragrunt.hcl` with remote state, provider config, and common variables.

> **MANDATORY:** Before generating, READ the template file:
> ```
> Read: assets/templates/root/terragrunt.hcl
> ```

**Template:** `assets/templates/root/terragrunt.hcl`
**Patterns:** `references/common-patterns.md` → Root Configuration Patterns

**Key placeholders to replace:**
- `[BUCKET_NAME]`, `[AWS_REGION]`, `[DYNAMODB_TABLE]`
- `[TERRAFORM_VERSION]`, `[PROVIDER_NAME]`, `[PROVIDER_SOURCE]`, `[PROVIDER_VERSION]`
- `[ENVIRONMENT]`, `[PROJECT_NAME]`

**Root.hcl Design Principles:**
1. **Environment-agnostic by default** - Don't assume env.hcl exists at root level
2. **Use static values for provider/backend region** - Or use `get_env()` for runtime config
3. **State key uses `path_relative_to_include()`** - This automatically includes environment path
4. **Provider tags can be static** - Environment-specific tags go in child modules

### 2. Generate Child Module Configuration
Create child modules with dependencies, mock outputs, and proper includes.

> **MANDATORY:** Before generating, READ the template file:
> ```
> Read: assets/templates/child/terragrunt.hcl
> ```

**Template:** `assets/templates/child/terragrunt.hcl`
**Patterns:** `references/common-patterns.md` → Child Module Patterns

**Module source options:**
- Local: `"../../modules/vpc"`
- Git: `"git::https://github.com/org/repo.git//path?ref=v1.0.0"`
- Registry: `"tfr:///terraform-aws-modules/vpc/aws?version=5.1.0"`

### 3. Generate Standalone Module
Self-contained modules without root dependency.

> **MANDATORY:** Before generating, READ the template file:
> ```
> Read: assets/templates/module/terragrunt.hcl
> ```

**Template:** `assets/templates/module/terragrunt.hcl`

### Canonical Placeholder Replacement Map

Use this map for every generated output:

| Placeholder | Meaning | Example Replacement | Notes |
|-------------|---------|---------------------|-------|
| `[AWS_REGION]` | AWS region | `us-east-1` | Canonical region placeholder in all templates |
| `[ENVIRONMENT]` | Environment name | `dev` | Keep lowercase for directory naming |
| `[PROJECT_NAME]` | Project/application name | `payments-platform` | Use the same value in tags and names |
| `[BUCKET_NAME]` | Remote state S3 bucket | `acme-tfstate-prod` | Bucket must exist before first apply |
| `[DYNAMODB_TABLE]` | State lock table | `acme-terraform-locks` | Table must exist before first apply |
| `[PROVIDER_SOURCE]` | Terraform provider source | `hashicorp/aws` | Use fully qualified source |
| `[TERRAFORM_VERSION]` | Required Terraform/OpenTofu version | `1.8.5` | Used in both `terraform_version_constraint` and `required_version`. Keep compatible with module constraints. |

**Legacy alias normalization:** If you see `[REGION]` in older examples, treat it as `[AWS_REGION]` and replace it before validation.

### 4. Generate Multi-Environment Infrastructure
Complete directory structures for dev/staging/prod.

> **MANDATORY:** Before generating:
> 1. Determine architecture pattern (see Architecture Patterns section)
> 2. Read relevant templates for root, env, and child modules
> 3. Verify env.hcl placement and access patterns:
>    ```
>    Read: assets/templates/env/env.hcl
>    ```

**Patterns:** `references/common-patterns.md` → Environment-Specific Patterns

**Typical structure (Pattern A - Environment-Agnostic Root):**
```
infrastructure/
├── root.hcl              # Environment-AGNOSTIC root config
├── dev/
│   ├── env.hcl           # Dev environment variables
│   └── vpc/terragrunt.hcl
└── prod/
    ├── env.hcl           # Prod environment variables
    └── vpc/terragrunt.hcl
```

### 5. Generate Terragrunt Stacks (2025)
Infrastructure blueprints using `terragrunt.stack.hcl`.

> **MANDATORY:** Before generating, READ the template files:
> ```
> Read: assets/templates/stack/terragrunt.stack.hcl
> Read: assets/templates/catalog/terragrunt.hcl
> ```

**Docs:** [Stacks Documentation](https://terragrunt.gruntwork.io/docs/features/stacks/)
**Template:** `assets/templates/stack/terragrunt.stack.hcl`
**Catalog Template:** `assets/templates/catalog/terragrunt.hcl`
**Patterns:** `references/common-patterns.md` → Stacks Patterns

**Stack path rule:** Keep `no_dot_terragrunt_stack` mode consistent across dependent units. Do not mix direct-path and `.terragrunt-stack` generation in the same dependency chain.

**Commands:**
```bash
terragrunt stack generate    # Generate unit configurations
terragrunt stack run plan    # Plan all units
terragrunt stack run apply   # Apply all units
terragrunt stack output      # Get aggregated outputs
terragrunt stack clean       # Clean generated directories
```

### 6. Generate Feature Flags (2025)
Runtime control without code changes.

**Docs:** [Feature Flags Documentation](https://terragrunt.gruntwork.io/docs/features/feature-flags/)
**Patterns:** `references/common-patterns.md` → Feature Flags Patterns

> **CRITICAL:** Feature flag `default` values MUST be static (boolean, string, number).
> They CANNOT reference `local.*` values. Use static defaults and override via CLI/env vars.

**Correct:**
```hcl
feature "enable_monitoring" {
  default = false  # Static value - OK
}
```

**Incorrect:**
```hcl
feature "enable_monitoring" {
  default = local.env.locals.enable_monitoring  # Dynamic reference - FAILS
}
```

**Usage:**
```bash
terragrunt apply --feature enable_monitoring=true
# or
export TG_FEATURE="enable_monitoring=true"
```

**Environment-specific defaults:** Use different static defaults per environment file, not dynamic references.

### 7. Generate Exclude Blocks (2025)
Fine-grained execution control (replaces deprecated `skip`).

**Docs:** [Exclude Block Reference](https://terragrunt.gruntwork.io/docs/reference/config-blocks-and-attributes/#exclude)
**Patterns:** `references/common-patterns.md` → Exclude Block Patterns

**Actions:** `"plan"`, `"apply"`, `"destroy"`, `"all"`, `"all_except_output"`

**Production Recommendation:** For critical production resources, add exclude blocks to prevent accidental destruction:
```hcl
# Protect production databases from accidental destroy
exclude {
  if      = true
  actions = ["destroy"]
  exclude_dependencies = false
}

# Also use prevent_destroy for critical resources
prevent_destroy = true
```

### 8. Generate Errors Blocks (2025)
Advanced error handling (replaces deprecated `retryable_errors`).

**Docs:** [Errors Block Reference](https://terragrunt.gruntwork.io/docs/reference/config-blocks-and-attributes/#errors)
**Patterns:** `references/common-patterns.md` → Errors Block Patterns

### 9. Generate OpenTofu Engine Configuration (2025)
Use OpenTofu as the IaC engine.

**Docs:** [Engine Documentation](https://terragrunt.gruntwork.io/docs/features/engine/)
**Patterns:** `references/common-patterns.md` → OpenTofu Engine Patterns

### 10. Handling Custom Providers/Modules
When generating configs with custom providers:

1. **Identify** the provider name, source, and version
2. **Search** using WebSearch: `"[provider] terraform provider [version] documentation"`
3. **Or use Context7 MCP** if available for structured docs
4. **Generate** with proper `required_providers` block
5. **Document** authentication requirements in comments

## Generation Workflow

> **CRITICAL:** Follow this workflow for EVERY generation task. Skipping steps leads to validation errors.

### Step 1: Understand Requirements
- What type of configuration? (root, child, standalone, stack)
- Single or multi-environment?
- What dependencies exist between modules?
- What providers/modules will be used?

### Step 2: Determine Architecture Pattern
> **MANDATORY:** Select and document the pattern BEFORE writing any files.

| Scenario | Pattern | Root.hcl Scope |
|----------|---------|----------------|
| Multi-env with shared root | Pattern A | Environment-agnost

---

Source: [Claudary](https://claudary.paisolsolutions.com/skills/skill-110) · https://claudary.paisolsolutions.com