for each module reference between modules with a map object - terraform

Question

im trying to create an instance group with reference to an GCE, but im unable to refer to the id from instance group to link to the GCE
variable "compute_engine_instances" {
type = map(object({
instance_name = string
machine_type = string
zone = string
tags = list(string)
image_name = string
image_project = string
labels =object({
app_id = number
cost_center = string
owner = string
email = string
})
}))
}
module "qat_hosted_pacs_compute_engines" {
source = "../modules/compute_engine"
for_each = var.compute_engine_instances
project_id = var.project_id
instance_name = each.value.instance_name
machine_type = each.value.machine_type
tags = each.value.tags
labels = each.value.labels
subnetwork = var.subnetwork
zone = each.value.zone
image_name = each.value.image_name
image_project = each.value.image_project
}
variable "instance_group" {
type = map(object({
group_manager_name = string
zone = string
}))
}
module "qat_hosted_pacs_app_grp" {
source = "../modules/instance_groups"
for_each = var.instance_group
group_manager_name = each.value.group_manager_name
zone = each.value.zone
project_id = var.project_id
instances = module.qat_hosted_pacs_compute_engines.vm_name #unable to figure out how to reference the GCE
}
#output.tf looks like this for compute engine module
output "compute_engine_instances" {
value = {
for k, v in module.qat_hosted_pacs_compute_engines : k => v.vm_name
}
}
The root module looks like this for compute engine
data "google_compute_image" "compute_image" {
name = var.image_name
project = var.image_project
}
resource "google_compute_instance" "generic_instance" {
project = var.project_id
name = var.instance_name
machine_type = var.machine_type
zone = var.zone
tags = var.tags
labels = var.labels
boot_disk {
initialize_params {
image = data.google_compute_image.compute_image.self_link
}
auto_delete = true
}
network_interface {
subnetwork = var.subnetwork
}
}
#outputs.tf here looks like this for gce resource
output "vm_name" {
value = google_compute_instance.generic_instance.id
description = "The name of the VM"
}
And the instance group manager looks like this
resource "google_compute_instance_group" "igm" {
name = var.group_manager_name
zone = var.zone
project = var.project_id
instances = var.instances
named_port {
name = "http"
port = "8080"
}
named_port {
name = "https"
port = "8443"
}
lifecycle {
create_before_destroy = true
}
}
i get the foll. error
Error: Unsupported attribute
on main.tf line 45, in module "qat_hosted_pacs_app_grp":
45: instances = module.qat_hosted_pacs_compute_engines.vm_name
|----------------
| module.qat_hosted_pacs_compute_engines is object with 2 attributes
This object does not have an attribute named "vm_name".
terraform tf vars file
compute_engine_instances ={
"test-adi"={
instance_name = "test-vm"
machine_type = "n1-standard-1"
zone = "us-east4-b"
tags = ["foo","bar"]
image_name = "gold-centos-7"
image_project = "dev-cietools"
labels = {
app_id = "56"
cost_center = "156"
owner = "ops"
email = "ops"
}}
"test-adi-2"={
instance_name = "test-vm-2"
machine_type = "n1-standard-1"
zone = "us-east4-b"
tags = ["foo","bar"]
image_name = "centos-7"
image_project = "dev-cietools"
labels = {
app_id = "56"
cost_center = "856"
owner = "ops"
email = "ops"
}
}
}
subnetwork = "sandbox-us-east4"
project_id = "cloudops-dev01-sb"
instance_group = {
"igm" = {
group_manager_name = "test"
zone = "us-east4-b"
}
}

Answer 1

Since you used for_each in your google_compute_instance_group module, you have to use key to refer to individual instances of the module, e.g.
instances = module.qat_hosted_pacs_compute_engines["test-adi"].vm_name
or if you want to pass all vm_name created for all values of for_each, you can do:
instances = values(module.qat_hosted_pacs_compute_engines)[*].vm_name