# Unit

> A single deployable infrastructure instance defined by a Terragrunt configuration file.

A *unit* is a single deployable infrastructure instance in the Panfactum stack. It corresponds to a directory containing a `terragrunt.hcl` file within the environments directory.

Each unit:

- Sources exactly one infrastructure module
- Has its own configuration (inputs, provider settings, dependencies)
- Maintains its own Terraform state file
- Is deployed and managed independently via `terragrunt apply`

In practice, a unit is what you interact with when running IaC commands — you navigate to a unit's directory and run `terragrunt plan` or `terragrunt apply`.

For example, in this environments layout:

```txt
environments/
  production/
    us-east-2/
      kube_cert_manager/
        terragrunt.hcl    <- this is a unit
      kube_vault/
        terragrunt.hcl    <- this is a unit
```

Each `terragrunt.hcl` represents a separate unit, even if multiple units source the same module.