Terraform: Subnet in use azurerm - azure

Question

Error Message
I get the following error message when executing terraform apply:
Error: Error Creating/Updating Virtual Network "CTI-NETWORK" (Resource Group "CTI-RESOURCES"): network.VirtualNetworksClient#CreateOrUpdate: Failure sending request: StatusCode=400 -- Original Error: Code="InUseSubnetCannotBeDeleted" Message="Subnet CTI-PRD is in use by /subscriptions/d92e8f07-e127-4015-b67a-a547af76fdfc/resourceGroups/CTI-RESOURCES/providers/Microsoft.Network/networkInterfaces/CTI-NIC-PRD1/ipConfigurations/CTI-IP-PRD1 and cannot be deleted. In order to delete the subnet, delete all the resources within the subnet. See aka.ms/deletesubnet." Details=[]
I assume I've got a dependency mixed up but cant seem to figure it out.
Code Snippet
Content of main.tf
provider "azurerm" {
version = "=1.38.0"
subscription_id = "d92e8f07-e127-4015-b67a-a547af76fdfc"
}
resource "azurerm_resource_group" "resourcegroup" {
name = "${var.prefix}RESOURCES"
location = var.location
}
resource "azurerm_virtual_network" "network" {
name = "${var.prefix}NETWORK"
resource_group_name = azurerm_resource_group.resourcegroup.name
address_space = ["10.0.0.0/16"]
location = var.location
}
resource "azurerm_subnet" "prd-subnet" {
name = "${var.prefix}PRD"
resource_group_name = azurerm_resource_group.resourcegroup.name
virtual_network_name = azurerm_virtual_network.network.name
address_prefix = "10.0.0.0/24"
}
resource "azurerm_subnet" "tst-subnet" {
name = "${var.prefix}TST"
resource_group_name = azurerm_resource_group.resourcegroup.name
virtual_network_name = azurerm_virtual_network.network.name
address_prefix = "10.0.1.0/24"
}
resource "azurerm_public_ip" "ip-prd-1" {
name = "${var.prefix}PIP-PRD1"
resource_group_name = azurerm_resource_group.resourcegroup.name
location = var.location
allocation_method = "Dynamic"
domain_name_label = "vm-prd-1"
}
resource "azurerm_network_interface" "nic-prd-1" {
name = "${var.prefix}NIC-PRD1"
resource_group_name = azurerm_resource_group.resourcegroup.name
location = var.location
ip_configuration {
name = "${var.prefix}IP-PRD1"
subnet_id = azurerm_subnet.prd-subnet.id
private_ip_address_allocation = "Dynamic"
public_ip_address_id = azurerm_public_ip.ip-prd-1.id
}
}
resource "azurerm_virtual_machine" "vm-prd-1" {
name = "${var.prefix}VM-PRD-1"
location = var.location
resource_group_name = azurerm_resource_group.resourcegroup.name
network_interface_ids = [azurerm_network_interface.nic-prd-1.id]
vm_size = var.size
delete_os_disk_on_termination = true
delete_data_disks_on_termination = true
storage_image_reference {
publisher = "credativ"
offer = "Debian"
sku = "9-backports"
version = "latest"
}
storage_os_disk {
name = "lin-disk-1"
caching = "ReadWrite"
create_option = "FromImage"
managed_disk_type = "Standard_LRS"
}
os_profile {
computer_name = "${var.prefix}IP-PRD1"
admin_username = "ADM-ADV"
admin_password = "!!W0rksh0p"
}
os_profile_linux_config {
disable_password_authentication = false
}
tags = {
environment = "Production"
application = "CTI Core"
}
}
resource "azurerm_public_ip" "ip-prd-2" {
name = "${var.prefix}PIP-PRD-2"
resource_group_name = azurerm_resource_group.resourcegroup.name
location = var.location
allocation_method = "Dynamic"
domain_name_label = "vm-prd-2"
}
resource "azurerm_network_interface" "nic-prd-2" {
name = "${var.prefix}NIC-PRD-2"
resource_group_name = azurerm_resource_group.resourcegroup.name
location = var.location
ip_configuration {
name = "${var.prefix}IP-PRD-2"
subnet_id = azurerm_subnet.prd-subnet.id
private_ip_address_allocation = "Dynamic"
public_ip_address_id = azurerm_public_ip.ip-prd-2.id
}
}
resource "azurerm_virtual_machine" "vm-prd-chef" {
name = "${var.prefix}VM-PRD-CHEF"
location = var.location
resource_group_name = azurerm_resource_group.resourcegroup.name
network_interface_ids = [azurerm_network_interface.nic-prd-2.id]
vm_size = var.size
delete_os_disk_on_termination = true
delete_data_disks_on_termination = true
storage_image_reference {
publisher = "Canonical"
offer = "UbuntuServer"
sku = "18.04-LTS"
version = "latest"
}
storage_os_disk {
name = "lin-disk-2"
caching = "ReadWrite"
create_option = "FromImage"
managed_disk_type = "Standard_LRS"
}
os_profile {
computer_name = "${var.prefix}IP-PRD-CHEF"
admin_username = "XXX"
admin_password = "XXX"
}
os_profile_linux_config {
disable_password_authentication = false
}
tags = {
environment = "Production"
application = "CTI Service"
}
provisioner "remote-exec" {
inline = [
"touch /root/test.txt"
]
}
}
Content of variables.tf
variable "prefix" {
type = string
default = "CTI-"
description = "Prefix of the resources"
}
variable "location" {
type = string
default = "westeurope"
description = "Location of the resources"
}
variable "size" {
type = string
default = "Standard_A1_v2"
description = "Size of the virtual machines"
}
Thanks for you help!

Answer 1

With the message you provided, you want to create another VM in the existing subnet of the Vnet. So you need to use the data resource instead of the resource format. Change your Terraform code like this:
Change:
resource "azurerm_virtual_network" "network" {
name = "${var.prefix}NETWORK"
resource_group_name = azurerm_resource_group.resourcegroup.name
address_space = ["10.0.0.0/16"]
location = var.location
}
resource "azurerm_subnet" "prd-subnet" {
name = "${var.prefix}PRD"
resource_group_name = azurerm_resource_group.resourcegroup.name
virtual_network_name = azurerm_virtual_network.network.name
address_prefix = "10.0.0.0/24"
}
Into:
data "azurerm_virtual_network" "network" {
name = "${var.prefix}NETWORK"
resource_group_name = azurerm_resource_group.resourcegroup.name
}
data "azurerm_subnet" "prd-subnet" {
name = "${var.prefix}PRD"
virtual_network_name = data.azurerm_virtual_network.network.name
resource_group_name = azurerm_resource_group.resourcegroup.name
}
resource "azurerm_network_interface" "nic-prd-1" {
name = "${var.prefix}NIC-PRD1"
resource_group_name = azurerm_resource_group.resourcegroup.name
location = var.location
ip_configuration {
name = "${var.prefix}IP-PRD1"
subnet_id = data.azurerm_subnet.prd-subnet.id
private_ip_address_allocation = "Dynamic"
public_ip_address_id = azurerm_public_ip.ip-prd-1.id
}
}
The Terraform data will quote the existing resource and do not change them. If the other subnet tst-subnet is also existing, you can change it like above yourself.