terraform .net 和 Su.net 模块

Question

I have a pipeline that downloads standard Terraform modules and creates resources.

1. "Module-ResourceGroup" deploys resource group.
2. "Module-.net" which deploys .net.
3. "Module-Su.net" which deploys su.nets.

My problem is when I kick the pipeline for the first time my pipeline fails reason because Module-Su.net gives me an error message that .net does not exist. However, when I run the same pipeline for a second time, my Su.nets get deployed without any issues as during the first run, then .net gets created.

I guess I have two solutions:

1. depends_on where I can say that by su.net module is dependent on .net module.
2. Introduce a wait of 3 mins in the su.net module before it gets executed.

Q1. why it is happening? whereas as per terraform "Most of the time, Terraform infers dependencies between resources based on the configuration given" https://learn.hashicorp.com/tutorials/terraform/dependencies if anything is wrong with the way I have written modules?

Q2. What is a better solution depends_on OR introduce wait

Q3. Is there any other way to fix it?

Below are my modules.

Module-ResourceGroup/main.tf

resource "azurerm_resource_group" "my-resourcegroup" {
  name     = format("%s-%s",var.resource_group_name,var.env)
  location = var.location
}

Module-.net/main.tf

resource "azurerm_virtual_network" "my-vnet" {
  name                = format("%s-%s",var.vnet_name,var.env)
  resource_group_name = format("%s-%s",var.resource_group_name,var.env)
  location            = var.location
  address_space       = var.address_space
}

Module-Su.net/main.tf

resource "azurerm_subnet" "my-subnet" {
  for_each = var.subnetsconfig
    name                 = format("%s-%s",each.key,var.env)
    address_prefixes     = each.value["address_prefixes"]
    virtual_network_name = format("%s-%s",var.vnet_name,var.env)
    resource_group_name  = format("%s-%s",var.resource_group_name,var.env)
}

Answer 1

If you use the output of a resource as the input of another resource then Terraform will understand it as an implicit dependency. For example (as you did not post all of your code):

Module-ResourceGroup/main.tf

resource "azurerm_resource_group" "my-resourcegroup" {
  name     = format("%s-%s",var.resource_group_name,var.env)
  location = var.location
}

Module-.net/main.tf

resource "azurerm_virtual_network" "my-vnet" {
  name                = format("%s-%s",var.vnet_name,var.env)
  resource_group_name = azurerm_resource_group.my-resourcegroup.name
  location            = var.location
  address_space       = var.address_space
}

Module-Su.net/main.tf

resource "azurerm_subnet" "my-subnet" {
  for_each             = var.subnetsconfig
  name                 = format("%s-%s",each.key,var.env)
  address_prefixes     = each.value["address_prefixes"]
  virtual_network_name = azurerm_virtual_network.my-vnet.name
  resource_group_name  = azurerm_resource_group.my-resourcegroup.name
}