refactor(k3s): streamline inventory and primary server IP handling

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

roles/k3s_loadbalancer/tasks/configuration.yml

@@ -0,0 +1,20 @@
+---
+- name: Template the nginx config file with dynamic upstreams
+  ansible.builtin.template:
+    src: templates/nginx.conf.j2
+    dest: "{{ k3s_loadbalancer_nginx_config_path }}"
+    owner: root
+    group: root
+    mode: "0644"
+  become: true
+  notify:
+    - Restart nginx
+  vars:
+    k3s_server_ips: "{{ groups['k3s_server'] | map('extract', hostvars, 'ansible_default_ipv4') | map(attribute='address') | unique | list }}"
+
+- name: Enable nginx
+  ansible.builtin.systemd:
+    name: nginx
+    daemon_reload: true
+    enabled: true
+  become: true