Terraform Environment Variables

Environment variables are set at the OS or platform level and made available to the Terraform runtime. These are not necessary, however they allow you to customize certain Terraform behaviors.

TF_LOG

For example the TF_LOG environment variable enables detailed logs to appear on stderr which is useful for debugging. For example:

MacOS

export TF_LOG=trace

To disable, either unset it, or set it to off. For example:

MacOS

export TF_LOG=off

Windows

$env:TF_LOG = "off"

TF_VAR_*

Another very helpful Terraform environment variable is TF_VAR_name. This environment variable can be used to set variables in Terraform where the name suffix is replaced with the name of your Terraform variable. For example:

MacOS

export TF_VAR_environment=prod

Windows

$env:TF_VAR_environment = "prod"

The variable must be defined in Terraform for this to work, and a default value can be set as a fail safe in case the variable is not set as an environment variable:

variable "environment" {
  type        = string
  description = "Contract ID"
  default     = "dev"
}

Akamai Credentials as TF_VAR_*

A very common use of this environment variables is to set the Akamai API credentials. The credentials must be made available as environment variables:

MacOS

• Export the variables:

export TF_VAR_akamai_client_secret="abc123"
export TF_VAR_akamai_host="abc123.luna.akamaiapis.net"
export TF_VAR_akamai_access_token="abc123"
export TF_VAR_akamai_client_token="abc123"
export TF_VAR_akamai_account_key="1-23ABC"

Windows

• Right-click Start Menu, select "Windows Powershell (Admin)"

$env:TF_VAR_akamai_client_secret = "abc123"
$env:TF_VAR_akamai_host = "abc123.luna.akamaiapis.net"
$env:TF_VAR_akamai_access_token = "abc123"
$env:TF_VAR_akamai_client_token = "abc123"
$env:TF_VAR_akamai_account_key = "1-23ABC"

If you're not working with more than one account disregard the TF_VAR_akamai_account_key and account_key below.

In your variables.tf you must define the variables:

variable "akamai_client_secret" {}
variable "akamai_host" {}
variable "akamai_access_token" {}
variable "akamai_client_token" {}
variable "akamai_account_key" {}

Finally the variables must be referenced in the provider block:

provider "akamai" {
  config {
    client_secret = var.akamai_client_secret
    host          = var.akamai_host
    access_token  = var.akamai_access_token
    client_token  = var.akamai_client_token
    account_key   = var.akamai_account_key
  }
}

Specific Environment Variables

Different platforms (e.g. Gitlab CI/CD, GiHub Workflows, etc) and different Terraform providers will make available their own environment variables which can be found in each of the developer's documentation.

For instance the environment variables for the Akamai Provider (opens in a new tab).

Exercise