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

resource "google_compute_network" "vpc" {
  name                    = "vpc"
  auto_create_subnetworks = false
  project                 = var.project_id
}

resource "google_compute_subnetwork" "frontend" {
  name          = "frontend-subnet"
  ip_cidr_range = var.frontend_cidr
  region        = var.region
  network       = google_compute_network.vpc.id
  project       = var.project_id
}

resource "google_compute_subnetwork" "backend" {
  name          = "backend-subnet"
  ip_cidr_range = var.backend_cidr
  region        = var.region
  network       = google_compute_network.vpc.id
  project       = var.project_id
}

resource "google_compute_subnetwork" "database" {
  name          = "database-subnet"
  ip_cidr_range = var.database_cidr
  region        = var.region
  network       = google_compute_network.vpc.id
  project       = var.project_id
}

resource "google_compute_firewall" "allow_http_https" {
  name    = "allow-http-https"
  network = google_compute_network.vpc.id
  project = var.project_id

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

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

resource "google_compute_firewall" "allow_ssh" {
  name    = "allow-ssh"
  network = google_compute_network.vpc.id
  project = var.project_id

  allow {
    protocol = "tcp"
    ports    = ["22"]
  }

  source_ranges = [var.ssh_source_ranges]
  target_tags   = ["all-instances"]
}

resource "google_compute_firewall" "frontend_to_backend" {
  name    = "frontend-to-backend-8000"
  network = google_compute_network.vpc.id
  project = var.project_id

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

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

resource "google_compute_firewall" "backend_to_database" {
  name    = "backend-to-database-3306"
  network = google_compute_network.vpc.id
  project = var.project_id

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

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