but3-iac/terraform/modules/network/main.tf

resource "google_compute_network" "vpc" {
  name = "vpc-1"
  auto_create_subnetworks = "false"
}

resource "google_compute_subnetwork" "frontend" {
  name = "subfr"
  network = google_compute_network.vpc.id
  ip_cidr_range = "10.0.1.0/24"
  region = "europe-west9"
}


resource "google_compute_subnetwork" "backend" {
  name = "subba"
  network = google_compute_network.vpc.id
  ip_cidr_range = "10.0.2.0/24"
  region = "europe-west9"
}


resource "google_compute_subnetwork" "database" {
  name = "subda"
  network = google_compute_network.vpc.id
  ip_cidr_range = "10.0.3.0/24"
  region = "europe-west9"
}


resource "google_compute_firewall" "allow_http_https"{
  name = "allowhttphttps"
  network = google_compute_network.vpc.id

  allow {
    protocol = "tcp"
    ports = ["80", "443"]
  }

  source_ranges = ["0.0.0.0/0"]
  target_tags = ["frontend"]
}


resource "google_compute_firewall" "ssh_f_b"{
  name = "sshfb"
  network = google_compute_network.vpc.id

  allow {
    protocol = "ssh"
    ports = ["8000"]
  }

  source_tags = ["frontend"]
  target_tags = ["backend"]
}


resource "google_compute_firewall" "ssh_b_d"{
  name = "sshbd"
  network = google_compute_network.vpc.id

  allow {
    protocol = "ssh"
    ports = ["3306"]
  }

  source_tags = ["backend"]
  target_tags = ["database"]
}