In this Terraform example, I explored two approaches to working with map variables. Firstly, I used a for loop to iterate over the key-value pairs in the address_prefixes map, extracting the prefix values and enclosing the loop within square brackets [] to generate list from map.
Alternatively, I discovered that I can leverage the values() function to extract the list of values from the map and directly assign it to an attribute that expects a list value, streamlining the process.
Additionally, I found that I can also use a list variable directly to supply values, providing another convenient option for working with collections in Terraform.
provider "azurerm" { features {} subscription_id = "9exxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxxx" } variable "subnet" { type = object({ name = string virtual_network_name = string resource_group_name = string address_prefixes = map(string) }) default = { name = "test_subnet" virtual_network_name = "vcloud_lab_global_vnet01" resource_group_name = "vcloud-lab.com" address_prefixes = { subnet1 = "10.0.5.0/24" subnet2 = "10.0.6.0/24" } } } # variable "address_prefixes" { # type = list(string) # default = ["10.0.1.0/24", "10.0.2.0/24"] # } resource "azurerm_subnet" "example" { name = var.subnet.name virtual_network_name = var.subnet.virtual_network_name resource_group_name = var.subnet.resource_group_name address_prefixes = [ for subnet_name, prefix in var.subnet.address_prefixes : prefix ] #values(var.subnet.address_prefixes) #var.address_prefixes }
Below is the plan output of azurerm_subnet, note the address_prefixes, It all looks good.
terraform plan Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols: + create Terraform will perform the following actions: # azurerm_subnet.example will be created + resource "azurerm_subnet" "example" { + address_prefixes = [ + "10.0.5.0/24", + "10.0.6.0/24", ] + default_outbound_access_enabled = true + id = (known after apply) + name = "test_subnet" + private_endpoint_network_policies = "Disabled" + private_link_service_network_policies_enabled = true + resource_group_name = "vcloud-lab.com" + virtual_network_name = "vcloud_lab_global_vnet01" } Plan: 1 to add, 0 to change, 0 to destroy. ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── Note: You didn't use the -out option to save this plan, so Terraform can't guarantee to take exactly these actions if you run "terraform apply" now.
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