terraform.tfvars

What is terraform.tfvars?

terraform.tfvars stores variable values separately from the variable declarations. Terraform loads it automatically.

Flow

terraform.tfvars   (values)
        ↓
variables.tf       (declarations)
        ↓
main.tf            (usage via var.*)

Example

variables.tf

variable "bucket_name" {}
 
variable "instance_type" {}

terraform.tfvars

bucket_name   = "venkat-demo-bucket"
instance_type = "t3.micro"

main.tf

resource "aws_s3_bucket" "demo" {
  bucket = var.bucket_name
}
 
resource "aws_instance" "example" {
  ami           = "ami-0db56f446d44f2f09"
  instance_type = var.instance_type
}

Override on the command line

terraform apply -var="instance_type=t3.medium"

For that run, Terraform uses t3.medium instead of the tfvars value.

Custom var files

Keep environment-specific values in separate files:

dev.tfvars
prod.tfvars

Apply with:

terraform apply -var-file="dev.tfvars"