# Terragrunt 1 0

> Apply Terragrunt 1.0 HCL, CLI, orchestration, migration, and behaviour changes. Load for Terragrunt work targeting 1.0 or later when the model's knowledge may predate the 2026-03-30 release.

- Skill: `cedws/terragrunt-1-0` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add cedws/terragrunt-1-0`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cedws/terragrunt-1-0/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: cedws (https://skillmd.com/u/cedws)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cedws/terragrunt-1-0

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# Terragrunt 1.0

This overview applies to target Terragrunt versions of at least 1.0.

## Stability guarantee

Terragrunt 1.0 guarantees no breaking changes in minor 1.x releases; future breaking changes are reserved for a later major release. The maintained 1.0 Guarantees document defines boundary cases.

## Execution and discovery

Breaking change: every run uses a `.terragrunt-cache` directory, even without a `terraform.source`. Hidden unit files needed in the cache belong in `terraform.include_in_copy`.

Breaking change: the embedded TFLint was removed. TFLint hooks require an installed external binary, while Terragrunt retains integration conveniences such as `tflint init`.

Breaking change: `find` and `list` discover hidden configurations, including `.terragrunt-stack`, by default. The deprecated `--hidden` is a no-op; `--no-hidden` opts out.

Breaking change: `render --format=json` no longer discovers dependants. Graph filters on `find` provide that traversal. A directory containing both `terragrunt.hcl` and `terragrunt.stack.hcl` is now rejected as ambiguous.

On Windows, path-returning HCL functions emit native separators. Configurations requiring slash-normalised keys can transform the returned string explicitly.

## Reporting and delegation

The `--report-file` flag supports single-unit runs. Undefined flags that appear intended for OpenTofu or Terraform produce guidance to forward them after `--`.

Terragrunt 1.0 was continuously tested with OpenTofu 1.11.4 and Terraform 1.14.4; those are delegated-tool compatibility observations, not bundled versions.