Terragrunt

Terragrunt is a thin wrapper that provides extra tools for keeping your configurations “Don’t Repeat Yourself” (DRY), working with multiple Terraform modules, and managing remote states.

Running Terragrunt with OpenTofu / Terraform

The env0 platform supports running Terragrunt with either OpenTofu or Terraform.

By default the selected TF binary is OpenTofu. In order to change that, you should open the Advanced settings and select which TF binary to use:

You can check Terragrunt's Terraform and OpenTofu version compatibility table here.

Run-all Terragrunt command checkbox

Within Terragrunt template configuration, under Advanced settings - check Execute run-all commands on multiple modules

• Adds run-all to each command, read more here.
• Supported from version 0.28.1.

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Local Terraform State

By default, env0 stores the local state for next deployments.

In some cases, we will not be able to store the local state for your Terragrunt modules. Please configure a remote backend with your Terragrunt code Remote terraform code, otherwise your Terragrunt code may not work properly with env0.

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Cross-Module Dependencies

env0's Terraform deployment flow includes a plan step and an apply step that uses the plan's results (plan file/s) to ensure every change is aligned between both steps.

According to the official docs, the run-all plan -out=/path/to/plan-file command we use will fail if there are yet-to-be-applied dependencies between modules. It will only output some of the expected plan files. This leads to the failure of the run-all apply /path/to/plan-file command that is being executed next, since it expects all modules to have plan files.

As a workaround, we expose the ENV0_OMIT_TERRAGRUNT_RUN_ALL_PLAN_FILE environment variable. Simply set its value to true and deploy. The run-all plan and run-all apply commands will be executed without passing plan files between them. This is risky and should only be done on initial deployment. On success, it is advised to remove this environment variable in order to keep the plan and apply steps in-sync.

Target modules

env0 supports terragrunt include dir , which is a CLI Arg for Terragrunt environment that runs in a run-all mode by using environment variable ENV0_TERRAGRUNT_RUN_ALL_INCLUDE_DIRS. Terragrunt will plan and apply only those modules and their dependencies when you use this variable.

Example:

ENV0_TERRAGRUNT_RUN_ALL_INCLUDE_DIRS=module1,path_to_module/module2

Smart detect Terragrunt modules changes

If you use Terragrunt run all PR Plan feature you can use our plugin for running plan only for changed modules in the PR

Troubleshooting

There is a known issue with terragrunt run-all plan -destroy -out=.tf-plan generating an incorrectly ordered graph. Thus, if you have dependency issues with run-all destroy, please use ENV0_OMIT_TERRAGRUNT_RUN_ALL_PLAN_FILE=true in your pipeline to ignore the plan file.

Suggested Blog Content

Terraform Modules Guide

Terraform Plan Examples

Managing Terraform Variable Hierarchy

Manage Terraform Remote State with a Remote Backend