Reading, Generating & Modifying Configuration

A `variable "NAME" {}` block. It accepts arguments like type, default, description, sensitive, nullable, and a validation block.

type, default, description, sensitive, nullable, and a nested validation block.

Terraform prompts interactively for the value at plan/apply time; the variable is required.

Defaults < environment (TF_VAR_name) < terraform.tfvars / *.auto.tfvars < -var-file < -var on the CLI. Later sources override earlier ones.

By reading an env var named TF_VAR_<name>; e.g. TF_VAR_region sets var.region.

terraform.tfvars (and terraform.tfvars.json) and any file matching *.auto.tfvars (or *.auto.tfvars.json).