Strict Controls

Terragrunt supports operating in a mode referred to as “Strict Mode”.

Strict Mode is a set of controls that can be enabled to ensure that your Terragrunt usage is future-proof by making deprecated features throw errors instead of warnings. This can be useful when you want to ensure that your Terragrunt code is up-to-date with the latest conventions to avoid breaking changes in future versions of Terragrunt.

Whenever possible, Terragrunt will initially provide you with a warning when you use a deprecated feature, without throwing an error. However, in Strict Mode, these warnings will be converted to errors, which will cause the Terragrunt command to fail.

A good practice for using strict controls is to enable Strict Mode in your CI/CD pipelines for lower environments to catch any deprecated features early on. This allows you to fix them before they become a problem in production in a future Terragrunt release.

If you are unsure about the impact of enabling strict controls, you can enable them for specific controls to gradually increase your confidence in the future compatibility of your Terragrunt usage.

Controlling Strict Mode

The simplest way to enable strict mode is to set the strict-mode flag.

This will enable strict mode for all Terragrunt commands, for all strict mode controls.

$ terragrunt run-all plan
15:26:08.585 WARN   The `run-all plan` command is deprecated and will be removed in a future version. Use `terragrunt run --all plan` instead.

$ terragrunt --strict-mode run-all plan
15:26:23.685 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.

You can also use the environment variable, which can be more useful in CI/CD pipelines:

$ TG_STRICT_MODE='true' terragrunt run-all plan
15:26:23.685 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.

Instead of enabling strict mode like this, you can also enable specific strict controls by setting the strict-control flag to a value that’s specific to a particular strict control. This can allow you to gradually increase your confidence in the future compatibility of your Terragrunt usage.

$ terragrunt run-all plan --strict-control cli-redesign
15:26:08.585 WARN   The `run-all plan` command is deprecated and will be removed in a future version. Use `terragrunt run --all plan` instead.

$ terragrunt run-all plan --strict-control cli-redesign
15:26:23.685 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.

Again, you can also use the environment variable, which might be more useful in CI/CD pipelines:

$ TG_STRICT_CONTROL='cli-redesign' terragrunt run-all plan
15:26:23.685 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.

You can enable multiple strict controls at once:

$ terragrunt run-all plan --strict-control cli-redesign --strict-control default-command
15:26:23.685 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.
15:26:46.521 ERROR  Unable to determine underlying exit code, so Terragrunt will exit with error code 1

$ terragrunt run-all apply --strict-control cli-redesign --strict-control default-command
15:26:46.564 ERROR  The `run-all apply` command is no longer supported. Use `terragrunt run --all apply` instead.
15:26:46.564 ERROR  Unable to determine underlying exit code, so Terragrunt will exit with error code 1

You can also enable multiple strict controls at once when using the environment variable by using a comma-delimited list.

$ TG_STRICT_CONTROL='cli-redesign,default-command' bash -c 'terragrunt run-all plan; terragrunt run-all apply'
15:26:46.521 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.
15:26:46.521 ERROR  Unable to determine underlying exit code, so Terragrunt will exit with error code 1
15:26:46.564 ERROR  The `run-all apply` command is no longer supported. Use `terragrunt run --all apply` instead.
15:26:46.564 ERROR  Unable to determine underlying exit code, so Terragrunt will exit with error code 1

You can also use control categories to enable certain categories of strict controls.

$ terragrunt run-all plan --strict-control deprecated-commands
15:26:23.685 ERROR  The `run-all plan` command is no longer supported. Use `terragrunt run --all plan` instead.

Strict Mode Controls

The following strict mode controls are available:

skip-dependencies-inputs

Disable reading of dependency inputs to enhance dependency resolution performance by preventing recursively parsing Terragrunt inputs from dependencies.

Reason: Enabling the skip-dependencies-inputs option prevents the recursive parsing of Terragrunt inputs, leading to optimized performance during dependency resolution.

require-explicit-bootstrap

Require explicit usage of --backend-bootstrap to automatically bootstrap backend resources.

root-terragrunt-hcl

Throw an error when users try to reference a root terragrunt.hcl file using find_in_parent_folders.

This control will also try to find other scenarios where users may be using terragrunt.hcl as the root configuration, including when using commands like scaffold and catalog, which can generate a terragrunt.hcl file expecting a terragrunt.hcl file at the root of the project. Enabling this flag adjusts the defaults for those commands so that they expect a recommended root.hcl file by default, and will throw an error if a terragrunt.hcl file is explicitly set.

Reason: Using a root terragrunt.hcl file was previously the recommended pattern to use with Terragrunt, but that is no longer the case. For more information see Migrating from root terragrunt.hcl.

terragrunt-prefix-flags

Throw an error when using the --terragrunt- prefix for flags.

Reason: This is no longer necessary, due to the work in RFC #3445. Example: The --terragrunt-non-interactive flag is deprecated and will be removed in a future version. Use --non-interactive instead.

terragrunt-prefix-env-vars

Throw an error when using the TERRAGRUNT_ prefix for environment variables.

Reason: This prefix has been renamed to TG_ to shorten the prefix, due to the work in RFC #3445. Example: The TERRAGRUNT_LOG_LEVEL env var is deprecated and will be removed in a future version. Use TG_LOG_LEVEL=info instead.

default-command

Throw an error when using the Terragrunt default command.

Reason: Terragrunt now supports a special run command that can be used to explicitly forward commands to OpenTofu/Terraform when no shortcut exists in the Terragrunt CLI. Example: The default command is deprecated and will be removed in a future version. Use terragrunt run instead.

cli-redesign

Throw an error when using commands that were deprecated as part of the CLI redesign.

Commands:

run-all
graph
graph-dependencies
hclfmt
hclvalidate
output-module-groups
render-json
terragrunt-info
validate-inputs

Reason: These commands have been deprecated in favor of more consistent and intuitive commands as part of the CLI redesign. For more information, see the CLI Redesign Migration Guide.

bare-include

Throw an error when using a bare include.

Reason: Backwards compatibility for supporting bare includes results in a performance penalty for Terragrunt, and deprecating support provides a significant performance improvement. For more information, see the Bare Include Migration Guide.

Control Categories

Certain strict controls are grouped into categories to make it easier to enable multiple strict controls at once.

These categories change over time, so you might want to use the specific strict controls if you want to ensure that only certain controls are enabled.

deprecated-commands

Throw an error when using the deprecated commands.

Controls:

default-command
cli-redesign

Note: The individual *-all commands (plan-all, apply-all, destroy-all, output-all, validate-all, spin-up, tear-down) have been removed from Terragrunt and are no longer available as strict controls. Use terragrunt run --all for the modern equivalent.

deprecated-flags

Throw an error when using the deprecated flags.

Controls:

terragrunt-prefix-flags

deprecated-env-vars

Throw an error when using the deprecated environment variables.

Controls:

terragrunt-prefix-env-vars

deprecated-configs

Throw an error when using the deprecated Terragrunt configuration.

Controls:

skip-dependencies-inputs

Completed Controls

The following strict controls have been completed and are no longer needed:

legacy-all
spin-up
tear-down
plan-all
apply-all
destroy-all
output-all
validate-all

legacy-all

Status: Completed - The legacy *-all commands have been removed from Terragrunt.

This control was previously used to throw an error when using any of the legacy commands that were replaced by run-all. These commands have now been completely removed from Terragrunt as part of the deprecation schedule.

Previously controlled commands (now removed):

plan-all - Use terragrunt run --all plan instead
apply-all - Use terragrunt run --all apply instead
destroy-all - Use terragrunt run --all destroy instead
output-all - Use terragrunt run --all output instead
validate-all - Use terragrunt run --all validate instead
spin-up - Use terragrunt run --all apply instead
tear-down - Use terragrunt run --all destroy instead