Terraform, dynamic attach multiple disk to 1 vps - google-cloud-platform

Question

My problem is that I can't dynamically connect the created disks to the vps. The google_compute_disk_attach module cannot be used
Here is my code
What is the correct way in this situation?
resource "google_compute_instance" "vps" {
name = var.server_name
description = var.server_description
machine_type = var.server_type
zone = var.server_datacenter
deletion_protection = var.server_delete_protection
labels = var.server_labels
metadata = var.server_metadata
tags = var.server_tags
boot_disk {
auto_delete = false
initialize_params {
size = var.boot_volume_size
type = var.boot_volume_type
image = var.boot_volume_image
labels = var.boot_volume_labels
}
}
dynamic "attached_disk" {
for_each = { for vol in var.volumes : vol.volume_name => vol }
content {
source = element(var.volumes[*].volume_name, 0)
}
}
network_interface {
subnetwork = var.server_network
access_config {
nat_ip = google_compute_address.static_ip.address
}
}
resource "google_compute_disk" "volume" {
for_each = { for vol in var.volumes : vol.volume_name => vol }
name = each.value.volume_name
type = each.value.volume_type
size = each.value.volume_size
zone = var.server_datacenter
labels = each.value.volume_labels
}
volumes variables
volumes = [{
volume_name = "v3-postgres-saga-import-test-storage"
volume_size = "40"
volume_type = "pd-ssd"
volume_labels = {
environment = "production"
project = "v3"
type = "storage"
}
}, {
volume_name = "volume-vpstest2"
volume_size = "20"
volume_type = "pd-ssd"
volume_labels = {
environment = "production"
project = "v2"
type = "storage"
}
}]
if do something like that - error
source = google_compute_disk.volume[*].self_link
This object does not have an attribute named "self_link".

Answer 1

Since you've used for_each in google_compute_disk.volume, it will be a map, not a list. Thus you can list all self_link as follows:
source = values(google_compute_disk.volume)[*].self_link

Answer 2

You can also use the volume variable directly as map instead of Array :
variables.tf file :
variable "volumes" {
default = {
postgres_saga = {
volume_name = "v3-postgres-saga-import-test-storage"
volume_size = "40"
volume_type = "pd-ssd"
volume_labels = {
environment = "production"
project = "v3"
type = "storage"
}
},
volume_vpstest2 = {
volume_name = "volume-vpstest2"
volume_size = "20"
volume_type = "pd-ssd"
volume_labels = {
environment = "production"
project = "v2"
type = "storage"
}
}
}
}
Instead of variable, you can also use a local variable from json configuration. Example of structure of Terraform module :
project
module
main.tf
locals.tf
resource
volumes.json
volumes.json file
{
"volumes": {
"postgres_saga" : {
"volume_name" : "v3-postgres-saga-import-test-storage"
"volume_size" : "40"
"volume_type" : "pd-ssd"
"volume_labels" : {
"environment" : "production"
"project" : "v3"
"type" : "storage"
}
},
"volume_vpstest2" : {
"volume_name" : "volume-vpstest2"
"volume_size" : "20"
"volume_type" : "pd-ssd"
"volume_labels" : {
"environment" : "production"
"project" : "v2"
"type" : "storage"
}
}
}
}
locals.tf file
locals {
tables = jsondecode(file("${path.module}/resource/volumes.json"))["volumes"]
}
main.tf file :
resource "google_compute_instance" "vps" {
name = var.server_name
description = var.server_description
machine_type = var.server_type
zone = var.server_datacenter
deletion_protection = var.server_delete_protection
labels = var.server_labels
metadata = var.server_metadata
tags = var.server_tags
boot_disk {
auto_delete = false
initialize_params {
size = var.boot_volume_size
type = var.boot_volume_type
image = var.boot_volume_image
labels = var.boot_volume_labels
}
}
dynamic "attached_disk" {
for_each = [
var.volumes
# local.volumes
]
content {
source = attached_disk.value["volume_name"]
}
}
network_interface {
subnetwork = var.server_network
access_config {
nat_ip = google_compute_address.static_ip.address
}
}
}
resource "google_compute_disk" "volume" {
for_each = var.volumes
# local.volumes
name = each.value["volume_name"]
type = each.value["volume_type"]
size = each.value["volume_size"]
zone = var.server_datacenter
labels = each.value["volume_labels"]
}
With a map, you can directly use foreach without any transformation on google_compute_disk/volume resource.
You can also use this map in a dynamic bloc.