Terraform GCP groups: I am using FQDNs as in the DNS, but still get "The URL is malformed". What kind of URL is it looking for? – Debian

I’m using Terraform with GCP … I have the groups variable that I have not been able to get to work. Here’s the definitions:

resource "google_compute_instance_group" "vm_group" {
  name      = "vm-group"
  zone      = "us-central1-c"
  project   = "myproject-dev"
  instances = [google_compute_instance.east_vm.id, google_compute_instance.west_vm.id]
  named_port {
    name = "http"
    port = "8080"
  }

  named_port {
    name = "https"
    port = "8443"
  }

  lifecycle {
    create_before_destroy = true
  }
}

data "google_compute_image" "debian_image" {
  family  = "debian-9"
  project = "debian-cloud"
}

resource "google_compute_instance" "west_vm" {
  name         = "west-vm"
  project      = "myproject-dev"
  machine_type = "e2-micro"
  zone         = "us-central1-c"
  boot_disk {
    initialize_params {
      image = data.google_compute_image.debian_image.self_link
    }
  }
   network_interface {
    network = "default"
  }
  }

resource "google_compute_instance" "east_vm" {
  name         = "east-vm"
  project      = "myproject-dev"
  machine_type = "e2-micro"
  zone         = "us-central1-c"
  boot_disk {
    initialize_params {
      image = data.google_compute_image.debian_image.self_link
    }
  }
   network_interface {
    network = "default"
  }
  }

And here are the variables:

http_forward = true
https_redirect = true
create_address = true
project = "myproject-dev"
backends = {
    "yobaby" = {
             description = "my app"
         enable_cdn = false
         security_policy = ""
         custom_request_headers = null
         custom_response_headers = null
         iap_config = {
             enable = false
                 oauth2_client_id     = ""
                 oauth2_client_secret = ""
         }
          log_config = {
             enable = false
         sample_rate = 0
         }
     groups = [{group = "google_compute_instance_group.vm_group.id"}]

}
}

… this is my latest attempt to get a group value that works, but this one won’t work for me either; I still get

Error 400: Invalid value for field ‘resource.backends[0].group’: ‘google_compute_instance_group.vm_group.id’. The URL is malformed., invalid

I’ve tried this with DNS FQDNs and variations on the syntax above; still no go.

Thanks much for any advice whatsoever!