Wednesday, April 10, 2024

Terraform variables

Variables in terraform are input values used to parameterize your configuration. They are defined in a variables.tf file and there are a few ways to load them into terraform.

variable "image_id" {
  type = string
  default = ""
}

.tfvars files

These are reusable files used to overwrite the values in variables.tf file.

var_name=“value”

The format is similar to a .env file.

It isi common to have a file per environment dev.tfvars, prod.tfvars

You pass the name of the file to a terraform call using -var-file

-var

You can pass individual variables into terraform using -var

terraform plan -var “name=red”

This is fine for adhoc stuff but it’s likely you’ll want to use environment variables.

TF_VAR

You can set an environment variable with a prefix of TF_VAR_ followed by the variable name in your variables.tf file.

export TF_VAR_name=red 

This will overwrite the default value in the variables.tf file.

Makefile

A makefile is helpful when running your terraform commands as you can have one for each environment configured to pass the correct tfvars file

plan:
	terraform plan -var-file=“dev.tfvars

or if you have a .env file you can load in the variables using include, and prefix if needed.

include ../.env.local

export TF_VAR_cloudflare_api_token=$(CLOUDFLARE_API_TOKEN)