tfvars-tools

Tools for managing root configuration repos for multi-environment or multi-service cloud infrastructure.

Root configurations or root modules are the working directories from which you run the Terraform CLI. ℹ️

TLDR

findtfvars: Recursively finds .tfvars files in parent directories

tfvars-to-args: Converts a list of .tfvars files to Terraform command-line arguments.

Quick usage

Find all .tfvars files in parent directories and convert to Terraform arguments:

findtfvars | tfvars-to-args

Use in a Terraform command:

TF_ARGS=$(findtfvars | tfvars-to-args)
terraform plan ${TF_ARGS}

Overview

Whether your root config repo is structured as a

• Monorepo
• repo-per-environment
• repo-per-team
• repo-per-service

your configurations will fall into two categories:

1. Environment Independent

   • Variables may be set at any parent directory common to all environments
   • Organizational hierarchies can set variables to standardize cloud estate

2. Environment Specific

   • Variables should be set in the environment directory
   • Values take precedence over those established generally

Simplify Simplify Simplify

tfvars-tools simplifies the management of Terraform variables across different organizational structures and environments, ensuring consistency and flexibility in your cloud infrastructure configurations, while Keeping your Infra Repo DRY .

USAGE

Total Classic

Consider this multi-service / multi-environment monorepo:

/org
├── common.tfvars
├── service1
│   ├── service1-common.tfvars
│   ├── dev
│   │   ├── main.tf
│   │   └── dev.tfvars
│   └── prod
│       ├── main.tf
│       └── prod.tfvars
└── service2
    ├── service2-common.tfvars
    ├── dev
    │   ├── main.tf
    │   └── dev.tfvars
    └── prod
        ├── main.tf
        └── prod.tfvars

To apply Terraform for the dev environment of service1 (and keep your sanity):

cd /org/service1/dev
terraform apply $(findtfvars | tfvars-to-args)

This will apply variables in this order, with conflicts being resolved by favoring the most recent assignment:

/org/common.tfvars
/org/service1/service1-common.tfvars
/org/service1/dev/dev.tfvars

Examples

Example 1

Default use-case, Terraform

TF_ARGS=$(findtfvars | tfvars-to-args)
terraform plan ${TF_ARGS}

Example 2

With Custom format

TF_ARGS=$(findtfvars -f ".toml" | tfvars-to-args -format="--file=%s")
some_other_tool ${TF_ARGS}

Example 3

With verbose output

TF_ARGS=$(findtfvars | tfvars-to-args -verbose)
echo "Arguments: ${TF_ARGS}"
terraform plan ${TF_ARGS}

Usage Signature

findtfvars [OPTIONS]
  OPTIONS:
    -d, --dir DIR   Start searching from DIR (default: current directory)
    -h, --help      Show this help message

tfvars-to-args [OPTIONS]
  OPTIONS:
    -r, --reverse   Output args in the order they were found (default: reverse order)
    -h, --help      Show this help message

Environment variables:

• FINDTFVARS_MAX_DEPTH: Maximum directory depth to search (default: unlimited)
• TFVARS_TO_ARGS_PREFIX: Prefix for generated arguments (default: "-var-file=")

Config file: ~/.tfvars-toolsrc

max_depth=10
arg_prefix="--var-file="

INSTALL

For those who prefer their tools like their coffee - instant and strong:

# For Linux
curl -Lo tfvars-tools.tar.gz https://github.com/iancaseydouglas/tfvars-tools/releases/latest/download/tfvars-tools_Linux_x86_64.tar.gz

# For macOS
curl -Lo tfvars-tools.tar.gz https://github.com/iancaseydouglas/tfvars-tools/releases/latest/download/tfvars-tools_Darwin_x86_64.tar.gz

# Extract, make executable, and move to a directory in your PATH
tar xzf tfvars-tools.tar.gz
chmod +x findtfvars tfvars-to-args
sudo mv findtfvars tfvars-to-args /usr/local/bin/

Now go forth and DRY up your tfvars.

DEVELOP

So you like recursively defined functions, you say...

1. Clone the repo
2. Read the Makefile
3. make your way to glory
4. Open PR

SEE ALSO

Many of the functions in use by Terragrunt or similar tools can be achieved with a wrapper around the tfvars-tools.

Keep your Infra Repo DRY

Google Internal best practices for Root Config Repos