Importing azurerm_virtual_network subnets have null address_prefix

[MattGarnerAWR]

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Terraform Version

1.8.3

AzureRM Provider Version

3.115.0

Affected Resource(s)/Data Source(s)

azurerm_virtual_network

Terraform Configuration Files

resource "azurerm_virtual_network" "example" {
  name                = "vnet-uks-staging-test"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
  address_space       = ["10.0.0.0/24"]

  subnet {
    name           = "snet-${var.env}-test"
    address_prefix = "10.0.0.192/26"
    security_group = azurerm_network_security_group.example.id
  }

  subnet {
    name           = "snet-${var.env}-test-test"
    address_prefix = "10.0.0.0/26"
    security_group = azurerm_network_security_group.example.id
  }
}

Debug Output/Panic Output

~ resource "azurerm_virtual_network" "example" {
        id                      = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/virtualNetworks/vnet-uks-staging-test"
        name                    = "vnet-uks-staging-test"
      ~ subnet                  = [
          - {
              - id             = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/virtualNetworks/vnet-uks-staging-test/subnets/snet-staging-test"
              - name           = "snet-staging-test"
              - security_group = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/networkSecurityGroups/nsg-uks-staging-test"
                # (1 unchanged attribute hidden)
            },
          - {
              - id             = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/virtualNetworks/vnet-uks-staging-test/subnets/snet-staging-test-test"
              - name           = "snet-staging-test-test"
              - security_group = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/networkSecurityGroups/nsg-uks-staging-test"
                # (1 unchanged attribute hidden)
            },
          + {
              + address_prefix = "10.0.0.0/26"
              + id             = (known after apply)
              + name           = "snet-staging-test-test"
              + security_group = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/networkSecurityGroups/nsg-uks-staging-test"
            },
          + {
              + address_prefix = "10.0.0.192/26"
              + id             = (known after apply)
              + name           = "snet-staging-test"
              + security_group = "/subscriptions/xxx/resourceGroups/rg-uks-staging-network/providers/Microsoft.Network/networkSecurityGroups/nsg-uks-staging-test"
            },
        ]
        tags                    = {}
        # (8 unchanged attributes hidden)
    }

Expected Behaviour

Terraform should import the subnet address prefixes into state.

Actual Behaviour

The address prefixes are set as null in state after import, meaning they are set to be recreated with what is set in code.

Steps to Reproduce

1. terraform plan

Important Factoids

No response

References

No response

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