feat: Add terragrunt_validate_inputs hook to check unused and undefined inputs

[jmreicha]

Put an x into the box if that apply:

• This PR introduces breaking change.
• This PR fixes a bug.
• This PR adds new functionality.
• This PR enhances existing functionality.

Description of your changes

Adds the ability to define a new terragrunt_validate_inputs hook for checking for unused and undefined variables in terragrunt.hcl configuration files.

Note: This does seem to require auth. I haven't found a way to get the hook to work without first authenticating to the cloud provider I was testing with. Please let me know if there is a way around this.

Fixes #675

How can we test changes

Add the new pre-commit config:

- repo: https://github.com/jmreicha/pre-commit-terraform
    rev: tg-validate
    hooks:
      - id: terragrunt_validate_inputs
        args:
          - --args=--terragrunt-strict-validate

Intentionally introduce a misconfiguration in a terragrunt.hcl configuration.

inputs = {
	...
	foo = "bar"
}

Run the pre-comit hook and note the failure.

Terragrunt validate inputs...............................................Failed
- hook id: terragrunt_validate_inputs
- exit code: 1

WARN[0030] The following inputs passed in by terragrunt are unused:  prefix=[/home/jmreicha/github.com/lytx/cloudops-terragrunt/dataplatform/stage/us-west-2/redshift/ore-dp-non-prod-redshift-cluster]
WARN[0030]      - foo                                        prefix=[/home/jmreicha/github.com/lytx/cloudops-terragrunt/dataplatform/stage/us-west-2/redshift/ore-dp-non-prod-redshift-cluster]
WARN[0030]                                               prefix=[/home/jmreicha/github.com/lytx/cloudops-terragrunt/dataplatform/stage/us-west-2/redshift/ore-dp-non-prod-redshift-cluster]
INFO[0030] All required inputs are passed in by terragrunt  prefix=[/home/jmreicha/github.com/lytx/cloudops-terragrunt/dataplatform/stage/us-west-2/redshift/ore-dp-non-prod-redshift-cluster]
ERRO[0030] Terragrunt configuration has misaligned inputs. Strict mode enabled: true.
ERRO[0030] Unable to determine underlying exit code, so Terragrunt will exit with error code 1

[yermulnik]

LGTM (apart from unrelated formatting changes to README — please revert those unrelated changes, that were presumably applied automatically by your IDE)

ps: you may try and add the below to the config file of your VSCode to stop it from removing trailing dots from markdown

    "[markdown]": {
        "files.trimTrailingWhitespace": false
    }

[MaxymVlasov]

Or just install https://editorconfig.org/ plugin to your favorite editor. I'll add it to the contrib article

[yermulnik]

Or just install editorconfig.org plugin to your favorite editor. I'll add it to the contrib article

Ah, right! Thanks, Max. I always miss that we have .editorconfig in here =)

[MaxymVlasov]

Here we go: https://github.com/antonbabenko/pre-commit-terraform/blob/master/.github/CONTRIBUTING.md#required-tools-and-plugins-to-simplify-review-process

If you merge the last changes to your branch, you'll be able to use extensions settings too.

Sorry for the inconvenience, that should have been added a long time ago.

[jmreicha]

Thanks for comments, I’ll get the formatting fixed up.

[jmreicha]

I think I got reformatted properly 🤞

[yermulnik]

LGTM
Leaving final review to @MaxymVlasov

[MaxymVlasov]

Can we provide here link to docs about authentication or provide more details?

I not sure which authentification is mentioned here. valid creds in ~/.aws/ ~/.azure/ etc? Or if not Cloud account, which account then?

Are there any terragrunt docs or issues about that?

[jmreicha]

I was considering opening an issue, in my testing I am using AWS and iam_role. I will see if I can find a relevant link.

[jmreicha]

Updated. I will look at opening an issue separately in the Terragrunt project and update the note here if I get an answer.

I have a highly customized setup so most folks may not ever run into this.

[yermulnik]

LGTM

[antonbabenko]

This PR is included in version 1.92.0 🎉