---
name: generate
path: "stack/generate"
category: stack
description: Generate a stack of units based on configurations in a terragrunt.stack.hcl file.
usage: |
  Generate a stack of units based on configurations in a terragrunt.stack.hcl file.
sidebar:
  order: 400
examples:
  - description: Generate stacks of units using the configurations in all terragrunt.stack.hcl files found, starting in the current directory.
    code: |
      terragrunt stack generate
flags:
  - stack-generate-filter
  - no-cas
  - cas-clone-depth
---

import FileTree from "@components/vendored/starlight/FileTree.astro";
import { Aside } from "@astrojs/starlight/components";

## Generating a stack

```hcl
# terragrunt.stack.hcl

unit "mother" {
	source = "units/chicken"
	path   = "mother"
}

unit "father" {
	source = "./units/chicken"
	path   = "father"
}

unit "chick_1" {
	source = "./units/chick"
	path   = "chicks/chick-1"
}

unit "chick_2" {
	source = "units/chick"
	path   = "chicks/chick-2"
}
```

Running the following:

```bash
terragrunt stack generate
```

Generates the following stack:

<FileTree>

- terragrunt.stack.hcl
- .terragrunt-stack
  - mother
    - terragrunt.hcl
  - father
    - terragrunt.hcl
  - chicks
    - chick-1
      - terragrunt.hcl
    - chick-2
      - terragrunt.hcl

</FileTree>

<Aside type="note">
Parallel Execution: Stack generation runs concurrently to improve performance. The number of parallel tasks is determined by the `GOMAXPROCS` environment variable and can be explicitly controlled using the `--parallelism` flag:

```bash
terragrunt stack generate --parallelism 4
```

Automatic Discovery: The command automatically discovers all `terragrunt.stack.hcl` files within the directory structure and generates them in parallel.

Validation of Units and Stacks: During the stack generation, the system will validate that each unit and stack's target directory contains the appropriate configuration file (`terragrunt.hcl` for units and `terragrunt.stack.hcl` for stacks). This ensures the directories are correctly structured before proceeding with the stack generation.
To **skip this validation**, you can use the `--no-stack-validate` flag:

```bash
terragrunt stack generate --no-stack-validate
```

</Aside>

<Aside type="caution">
  Path Restrictions: If an absolute path is provided as an argument, `generate` will throw an error. Only relative paths
  within the working directory are supported.
</Aside>

<Aside type="caution">
Recreating the stack directory and cleaning stale files: By default, `terragrunt stack generate` does not delete files in `.terragrunt-stack` that are no longer produced by the current `terragrunt.stack.hcl`. If you removed or changed `values` or units and still see old files (e.g., a lingering `terragrunt.values.hcl`), regenerate from a clean state by either refreshing sources or cleaning the directory first:

```bash
# Refresh sources and regenerate from a clean copy
terragrunt stack generate --source-update

# Or explicitly remove the generated directory first
terragrunt stack clean && terragrunt stack generate
```

You can also pass `--source-update` when running commands via `stack run`:

```bash
terragrunt stack run plan --source-update
```

</Aside>
