refactor(k3s): centralize k3s primary server IP and integrate Netcup DNS

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/k3s_loadbalancer/tasks/main.yml

@@ -3,3 +3,14 @@
   ansible.builtin.include_tasks: installation.yml
 - name: Configure
   ansible.builtin.include_tasks: configuration.yml
+
+- name: Setup DNS on Netcup
+  community.general.netcup_dns:
+    api_key: "{{ k3s_loadbalancer_netcup_api_key }}"
+    api_password: "{{ k3s_loadbalancer_netcup_api_password }}"
+    customer_id: "{{ k3s_loadbalancer_netcup_customer_id }}"
+    domain: "{{ domain }}"
+    name: "k3s"
+    type: "A"
+    value: "{{ hostvars['k3s-loadbalancer'].ansible_default_ipv4.address }}"
+  delegate_to: localhost