GCP terraform compute instance template labels - google-cloud-platform

Question

I have a TF GCP google_compute_instance_template configured to deploy a range of individual VMs, each of which will perform a different role in a "micro-services" style application. I am adding a single label to my instance_template, costing="app". However when I go to deploy the various VM components of the app with google_compute_instance_group_manager, I was expecting to be able to add another label in the in the instance group manager configuration, specific to the VM that is being deployed, such as "component=blah". The google_compute_instance_group_manager is not talking labels as a configuration element. Does anyone know how I can use the template to add a generic label, but then add additional machine-specific labels when the VMs are created?
Here is the TF code:
// instance template
resource "google_compute_instance_template" "app" {
name = "appserver-template"
machine_type = var.app_machine_type
labels = {
costing = "app"
}
disk {
source_image = data.google_compute_image.debian_image.self_link
auto_delete = true
boot = true
disk_size_gb = 20
}
tags = ["compute", "app"]
network_interface {
subnetwork = var.subnetwork
}
// no access config
service_account {
email = var.service_account_email
// email = google_service_account.vm_sa.email
scopes = ["cloud-platform"]
}
}
// create instances --how to add instance-specific label here? eg component="admin"
resource "google_compute_instance_group_manager" "admin" {
provider = google-beta
name = "admin-igm"
base_instance_name = "${var.project_short_name}-admin"
zone = var.zone
target_size = 1
version {
name = "appserver"
instance_template = google_compute_instance_template.app.id
}
}

Answer 1

I got the desired outcome by creating a google_compute_instance_template for each server type in my application, which then allowed me to assign both a universal label and a component-specific label. It was more code than I hoped to have to write, but the objective is met.
resource "google_compute_instance_template" "admin" {
name = "admin-template"
machine_type = var.app_machine_type
labels = {
costing = "app",
component = "admin"
}
disk {
source_image = data.google_compute_image.debian_image.self_link
auto_delete = true
boot = true
disk_size_gb = 20
}
tags = ["compute"]
network_interface {
subnetwork = var.subnetwork
}
// no access config
service_account {
email = var.service_account_email
// email = google_service_account.vm_sa.email
scopes = ["cloud-platform"]
}
}