terragrunt-engine-terraform v0.1.0: Breaking Change Requires Terragrunt 0.99.0

The terragrunt-engine-terraform project published v0.1.0 on October 6, 2026. The headline change is a compatibility break: after this release, the engine only works with Terragrunt v0.99.0 or newer. Anyone running an older Terragrunt version should pin the previous engine release instead of upgrading. Full details are on the GitHub release page.

The full release notes and changelog are on the GitHub release page.

The breaking change

This version is built on terragrunt-engine-go v0.2.0, which carries a breaking change introduced in that library’s v0.1.0. The change reworked how the engine sends logging and stdout/stderr messages back to Terragrunt. Engine maintainers get better logging support, and messages between the engine and Terragrunt are smaller.

The side effect is a version floor: the engine now requires Terragrunt v0.99.0 or later. If you are below that, the release notes show the pin to use:

engine {
  source  = "github.com/gruntwork-io/terragrunt-engine-terraform"
  version = "v0.0.16"
}

That keeps you on v0.0.16 until you are ready to upgrade Terragrunt itself.

Toolchain and platform updates

A few maintenance changes landed alongside the break:

  • The build moved to Go 1.27, with the previous bump to Go 1.26 earlier in the same cycle.
  • The bundled Terraform version is now 1.5.7.
  • CI moved from the previous setup to GitHub Actions.

Dependency bumps also came in from dependabot and manual updates, including github.com/stretchr/testify going from 1.10.0 to 1.11.1. None of these change engine behavior directly, but they keep the build current.

Upgrade notes

Plan this upgrade together with your Terragrunt version:

  1. Check that you run Terragrunt v0.99.0 or newer. If so, moving to v0.1.0 is straightforward.
  2. If you are on an older Terragrunt, pin engine version v0.0.16 in the engine block as shown above.
  3. When you eventually upgrade Terragrunt, drop the pin and move to v0.1.0 in the same change so the versions stay matched.

Where to get it

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