Read tfvars in a forma

formae can read Terraform and OpenTofu .tfvars files directly inside a forma. Existing variable files from a Terraform or OpenTofu codebase can drive a formae deployment without conversion or duplication, so the same inputs stay shared between both tools while you migrate. The terraform.readTFVars() function parses an HCL-format .tfvars file and returns its variables as a Pkl Dynamic, so you read values with dot notation.

Read a tfvars file

Import the terraform extension

Add the import alongside your other Pkl imports at the top of the forma:

import "@formae/ext/terraform.pkl"

Read the file

Bind the parsed values to a local. The path is resolved relative to the forma file’s directory, and absolute paths also work:

local vars = terraform.readTFVars("prod.tfvars")

Access values with dot notation

Given this prod.tfvars:

region         = "us-west-2"
instance_count = 3
enable_logging = true
tags           = { Name = "web-server", Environment = "production" }
zones          = ["us-west-2a", "us-west-2b"]

the values come through as:

local vars = terraform.readTFVars("prod.tfvars")

vars.region          // "us-west-2"
vars.instance_count  // 3
vars.enable_logging  // true
vars.tags.Name       // "web-server"
vars.zones           // List("us-west-2a", "us-west-2b")

Example forma

This forma reads env/prod.tfvars and uses its values to set a target region and interpolate a queue name:

amends "@formae/forma.pkl"
import "@formae/formae.pkl"
import "@formae/ext/terraform.pkl"
import "@aws/aws.pkl"
import "@aws/sqs/queue.pkl"

local tfvars = terraform.readTFVars("env/prod.tfvars")

forma {
  new formae.Stack {
    label = "my-stack"
    description = "Stack using tfvars"
  }

  new formae.Target {
    label = "aws-target"
    config = new aws.Config {
      region = tfvars.region
    }
  }

  new queue.Queue {
    label = "my-queue"
    queueName = "app-\(tfvars.region)-queue"
  }
}

Apply it the same way as any other forma. formae shows the plan and asks you to confirm before making changes:

formae apply --mode reconcile prod.pkl

Use --simulate to preview the plan without applying, or --yes to skip the confirmation prompt.

Supported types

Values are mapped from HCL to Pkl types as follows:

tfvars type	Pkl type
`"string"`	`String`
`42`	`Int`
`3.14`	`Float`
`true` / `false`	`Boolean`
`["a", "b"]`	`List`
`{ key = "val" }`	`Dynamic` (dot-accessible)
`null`	`Null`
Heredoc (`<<EOF`)	`String`

What is supported

readTFVars reads HCL-format .tfvars files. The .tfvars.json format is not supported, and the file extension must be .tfvars. Values must be literals: variable references and function calls inside the file are not evaluated.

Get started

Guides

Concepts

Reference

Read tfvars in a forma

Read a tfvars file

Example forma

Supported types

What is supported

See also

​Read a tfvars file

​Example forma

​Supported types

​What is supported

​See also

Read a tfvars file

Example forma

Supported types

What is supported

See also