CODEWITHSUNDEEP
terraformhclterragruntterraform-template-file
williamcodes
williamcodes

Reputation: 7236

how to get terragrunt to read tfvars files into dependent modules

Anyone know how to get terragrunt to read tfvars files into dependent modules? If I declare all my tfvars as inputs in my root terragrunt.hcl, everything works fine, but of course then I can’t customize them by environment. I tried adding the extra_arguments block, but the variables aren’t declared in the root module. They’re declared in the dependent module and I don’t want to have to declare them in both places.

Here’s my setup:

// terraform/terragrunt.hcl

terraform {
  extra_arguments "common_vars" {
    commands = ["plan", "apply"]
    arguments = [
      "-var-file=${find_in_parent_folders("account.tfvars")}",
      "-var-file=./terraform.tfvars"
    ]
  }
}

locals {
  environment_vars = read_terragrunt_config(find_in_parent_folders("account.hcl"))
  bucket = local.environment_vars.locals.bucket
}

remote_state {
  backend = "s3"
  generate = {
    path      = "backend.tf"
    if_exists = "overwrite_terragrunt"
  }

  config = {
    key    = "${path_relative_to_include()}/terraform.tfstate"
    region = "us-east-1"
    bucket = local.bucket
  }
}

dependencies {
  paths = ["../../../shared/services", "../../../shared/core"]
}

// terraform/accounts/dev/account.tfvars

aws_region = "us-east-1"

// terraform/accounts/dev/william/terraform.tfvars

aws_vpc_cidr = "10.1.0.0/16"

// terraform/accounts/dev/william/terragrunt.hcl

include {
  path = find_in_parent_folders()
}

This doesn't work because the variable values don't actually get passed to the dependent modules. I got this back when I tried to run a terragrunt plan:

''' TERMINAL OUTPUT

$ terragrunt plan
No changes. Infrastructure is up-to-date.

This means that Terraform did not detect any differences between your
configuration and real physical resources that exist. As a result, no
actions need to be performed.

Warning: Value for undeclared variable
The root module does not declare a variable named
"aws_region" but a value was found in file
"/Users/williamjeffries/code/parachute/infrastructure/terraform/accounts/dev/account.tfvars".

To use this value, add a "variable" block to the configuration.
Using a variables file to set an undeclared variable is deprecated and will
become an error in a future release. If you wish to provide certain "global"
settings to all configurations in your organization, use TF_VAR_...
environment variables to set these instead.

Actually there were 26 such warnings, I’ve only pasted in one here but you get the idea. It seems like there should be some way to solve this with a terragrunt generate block but I'm not sure how. Any ideas?

Upvotes: 3

Views: 5502

Answers (1)

David Tam
David Tam

Reputation: 546

I have been following the documentation here where it suggested to have directory structure:

live
├── prod
│   ├── app
│   │   └── terragrunt.hcl
│   ├── mysql
│   │   └── terragrunt.hcl
│   └── vpc
│       └── terragrunt.hcl
├── qa
│   ├── app
│   │   └── terragrunt.hcl
etc...

and

# content of qa/app/terragrunt.hcl
terraform {
  # Deploy version v0.0.3 in qa
  source = "git::[email protected]:foo/modules.git//app?ref=v0.0.3"
}

inputs = {
  # tfvars for qa
  instance_count = 3
  instance_type  = "t2.micro"
}

and

# content of prod/app/terragrunt.hcl
terraform {
  # Deploy version v0.0.3 in prod
  source = "git::[email protected]:foo/modules.git//app?ref=v0.0.3"
}

inputs = {
  # tfvars for prod
  instance_count = 20
  instance_type  = "t2.2xlarge"
}

and then the source could be within the same git repo., i.e: just app directory. You could then customize module app by different environment (and even different versions in different environments)

Upvotes: 1

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