firewall.tf

resource "google_compute_firewall" "vpc_firewall" {
  name    = "test-firewall"
  network = google_compute_network.vpc_network.name

  allow {
    protocol = "icmp"
  }

  allow {
    protocol = "tcp"
    ports    = ["22", "80", "8080", "1000-2000"]
  }

  source_ranges = ["0.0.0.0/0"]
  target_tags   = ["klim-web"]
}

main.tf

provider "google" {
  version = "3.5.0"

  credentials = file("../nacita-dev-terraform-demo.json")

  project = var.project
  region  = var.region
  zone    = var.zone
}

# New resource for the storage bucket our application will use.
resource "google_storage_bucket" "example_bucket" {
  name     = "klim-terraform-demo"
  location = "US"

  website {
    main_page_suffix = "index.html"
    not_found_page   = "404.html"
  }
}


resource "google_compute_instance" "vm_instance" {

  depends_on = [google_storage_bucket.example_bucket]

  name         = "terraform-instance"
  machine_type = "f1-micro"
  tags         = ["klim-web"]

  boot_disk {
    initialize_params {
      //image = "debian-cloud/debian-9"
      image = "cos-cloud/cos-stable"
    }
  }

  network_interface {
    network    = google_compute_network.vpc_network.name
    subnetwork = google_compute_subnetwork.vpc_subnetwork.name
    access_config {
      nat_ip = google_compute_address.vm_ip_static.address
    }
  }
}

network.tf

resource "google_compute_network" "vpc_network" {
  name                    = "terraform-network"
  auto_create_subnetworks = false
}

resource "google_compute_subnetwork" "vpc_subnetwork" {
  ip_cidr_range            = "10.4.4.0/24"
  name                     = "terraform-subnet"
  network                  = google_compute_network.vpc_network.name
  private_ip_google_access = "false"
}

resource "google_compute_address" "vm_ip_static" {
  name = "ip-static-terraform"
}

terraform-notes.txt

- install terraform

wget https://releases.hashicorp.com/terraform/0.12.26/terraform_0.12.26_linux_amd64.zip
unzip terraform_0.12.26_linux_amd64.zip 

- credential 

export GOOGLE_APPLICATION_CREDENTIALS=

- file main.tf

terraform.tfvars

project = "nacita-dev"
region  = "asia-souteast2"
zone    = "asia-southeast2-b"

variable.tf

variable "project" {
  type = string
}
variable "region" {
  default = "us-central1"
}

variable "zone" {
  default = "us-central1-b"
}