Bonus

terraform/modules/compute/main.tf

@@ -96,4 +96,50 @@ resource "google_compute_instance" "database" {
     email  = var.service_account_email
     scopes = ["userinfo-email", "compute-ro"]
   }
-}
+}
+
+resource "google_compute_instance_template" "frontend_template" {
+  name         = "${var.project_id}-frontend-template"
+  project      = var.project_id
+  machine_type = var.instance_type
+
+  tags   = ["frontend", "ssh"]
+  labels = merge({ tier = "frontend" }, var.labels)
+
+  metadata = {
+    enable-oslogin = "TRUE"
+    ssh-keys       = var.ssh_pub_key
+    custom-value   = "custom-metadata"
+  }
+
+  disk {
+    auto_delete  = true
+    boot         = true
+    source_image = "debian-cloud/debian-11"
+  }
+
+  network_interface {
+    network    = var.network_id
+    subnetwork = var.frontend_subnet_id
+    access_config {}
+  }
+
+  service_account {
+    email  = var.service_account_email
+    scopes = ["userinfo-email", "compute-ro"]
+  }
+}
+
+
+resource "google_compute_region_instance_group_manager" "frontend_mig" {
+  name               = "${var.project_id}-frontend-mig"
+  project            = var.project_id
+  region             = var.region
+  base_instance_name = "frontend"
+
+  version {
+    instance_template = google_compute_instance_template.frontend_template.self_link
+  }
+
+  target_size = var.instance_count
+}