How can I reference a variable in `main.tf`?

Question

I have two terraform files main.tf and var.tfvars:

main.tf:

provider "google" {
  project = var.project_id
  region  = var.gcp_region
}

provider "aws" {
  region = var.aws_region
    alias = "aws"
}

vars.tfvars:

variable "gcp_region" {
    type = string
    default = "asia-southeast1"
}

variable "aws_region" {
    type = string
    default = "ap-southeast-2"
}

variable "project_id" {
    type = string
    default = "test-oidc-arosha"
}

when I run terraform apply, I got below error:

Error: Reference to undeclared input variable
│
│   on local.tf line 6, in locals:
│    6:     state_backet = "${local.component_name}-${local.part_name}-deployment-${var.aws_region}-${data.aws_caller_identity.current.account_id}"
│
│ An input variable with the name "aws_region" has not been declared. This variable can be declared
│ with a variable "aws_region" {} block.
╵
╷
│ Error: Reference to undeclared input variable
│
│   on main.tf line 2, in provider "google":
│    2:   project = var.project_id
│
│ An input variable with the name "project_id" has not been declared. This variable can be declared
│ with a variable "project_id" {} block.
╵
╷
│ Error: Reference to undeclared input variable
│
│   on main.tf line 3, in provider "google":
│    3:   region  = var.gcp_region
│
│ An input variable with the name "gcp_region" has not been declared. This variable can be declared
│ with a variable "gcp_region" {} block.

I don't understand why I got this error even I already specified the default values for each variable.

My terraform version is:

$ terraform --version
Terraform v1.0.0
on darwin_amd64
+ provider registry.terraform.io/hashicorp/aws v3.45.0
+ provider registry.terraform.io/hashicorp/google v3.72.0

Answer 1

you need to add variable definition to your main.tf and then use your variable in var.tf approapriately

example

 variable "aws_region" {
    type = string
    default = "ap-southeast-2"
}

var.tfvars

example

aws_region = {
    Name = "created by jatin/terraform",
    instance_type="t2.micro"
}