tp_cloud/terraform/modules/network/main.tf

resource "google_compute_network" "my_vpc" {
  name                    = "my-vpc"
  auto_create_subnetworks = false
}

resource "google_compute_subnetwork" "frontend" {
  name          = "frontend"
  ip_cidr_range = var.frontend_cidr
  region        = var.region
  network       = google_compute_network.my_vpc.id
}

resource "google_compute_subnetwork" "backend" {
  name          = "backend"
  ip_cidr_range = var.backend_cidr
  region        = var.region
  network       = google_compute_network.my_vpc.id
}

resource "google_compute_subnetwork" "database" {
  name          = "database"
  ip_cidr_range = var.database_cidr
  region        = var.region
  network       = google_compute_network.my_vpc.id
}

resource "google_compute_firewall" "web" {
  name       = "web"
  network    = google_compute_network.my_vpc.id
  allow { 
    protocol = "tcp"
    ports = ["80", "443"]
  }
}

resource "google_compute_firewall" "ssh" {
  name       = "ssh"
  network    = google_compute_network.my_vpc.id
  allow {
    protocol = "tcp"
    ports = ["22"]
  }
}

resource "google_compute_firewall" "frontend_to_backend" {
  name       = "frontend-to-backend"
  network    = google_compute_network.my_vpc.id
  allow {
    protocol = "tcp"
    ports = ["8000"]
  }
  source_ranges = [
    google_compute_subnetwork.frontend.ip_cidr_range
  ]
  target_tags = ["backend"]
}

resource "google_compute_firewall" "backend_to_database" {
  name       = "backend-to-database"
  network    = google_compute_network.my_vpc.id
  allow {
    protocol = "tcp"
    ports = ["3306"]
  }
  source_ranges = [
    google_compute_subnetwork.backend.ip_cidr_range
  ]
  target_tags = ["db"]
}