title: How to configure environment variables in Hashicorp Terraform
body: <p>I'm quite new to Terraform, though I have gone through all of the instructional modules available on Hashicorp's site. </p>
  
  <p>Currently, I'm struggling with understanding how to set up environment variables. I know how to reference variables in the main.tf config (<code>access_key = "${var.access_key}"</code>), and I know how to save that access key to a separate file and reference that, but what I don't understand (and can't find any documentation/instruction on) is how to set up environment variables so I don't have to save the access key to a file.</p>
  
  <p>Does anyone know how best to go about doing this?</p>