feat(iaas): support for v2 API (#1070)

relates to STACKITTPR-313

docs/resources/network_area_region.md

@@ -0,0 +1,77 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "stackit_network_area_region Resource - stackit"
+subcategory: ""
+description: |-
+  Network area region resource schema.
+---
+
+# stackit_network_area_region (Resource)
+
+Network area region resource schema.
+
+## Example Usage
+
+```terraform
+resource "stackit_network_area_region" "example" {
+  organization_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  network_area_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  ipv4 = {
+    transfer_network = "10.1.2.0/24"
+    network_ranges = [
+      {
+        prefix = "10.0.0.0/16"
+      }
+    ]
+  }
+}
+
+# Only use the import statement, if you want to import an existing network area region
+import {
+  to = stackit_network_area_region.import-example
+  id = "${var.organization_id},${var.network_area_id},${var.region}"
+}
+```
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `ipv4` (Attributes) The regional IPv4 config of a network area. (see [below for nested schema](#nestedatt--ipv4))
+- `network_area_id` (String) The network area ID.
+- `organization_id` (String) STACKIT organization ID to which the network area is associated.
+
+### Optional
+
+- `region` (String) The resource region. If not defined, the provider region is used.
+
+### Read-Only
+
+- `id` (String) Terraform's internal resource ID. It is structured as "`organization_id`,`network_area_id`,`region`".
+
+<a id="nestedatt--ipv4"></a>
+### Nested Schema for `ipv4`
+
+Required:
+
+- `network_ranges` (Attributes List) List of Network ranges. (see [below for nested schema](#nestedatt--ipv4--network_ranges))
+- `transfer_network` (String) IPv4 Classless Inter-Domain Routing (CIDR).
+
+Optional:
+
+- `default_nameservers` (List of String) List of DNS Servers/Nameservers.
+- `default_prefix_length` (Number) The default prefix length for networks in the network area.
+- `max_prefix_length` (Number) The maximal prefix length for networks in the network area.
+- `min_prefix_length` (Number) The minimal prefix length for networks in the network area.
+
+<a id="nestedatt--ipv4--network_ranges"></a>
+### Nested Schema for `ipv4.network_ranges`
+
+Required:
+
+- `prefix` (String) Classless Inter-Domain Routing (CIDR).
+
+Read-Only:
+
+- `network_range_id` (String)