fix(k3s-server): serialize master joins and capture diagnostics

- validate host-only connectivity before cluster bootstrap\n- materialize per-host join arguments and wait for sequential registration\n- collect bounded network diagnostics when k3s initialization fails

roles/k3s_server/tasks/join_master.yml

@@ -1,34 +1,18 @@
 ---
-- name: Verify primary Kubernetes API is reachable from {{ joining_master }}
-  ansible.builtin.wait_for:
-    host: "{{ hostvars[groups[group_name_master | default('master')][0]].k3s_node_ip | split(',') | first }}"
-    port: 6443
-    connect_timeout: 5
-    timeout: "{{ retry_count | default(20) * 2 }}"
-  delegate_to: "{{ joining_master }}"
-
 - name: Join transient k3s-init service for {{ joining_master }}
   ansible.builtin.command:
     cmd: >-
       systemd-run -p RestartSec=2 -p Restart=on-failure --unit=k3s-init
-      k3s server {{ joining_server_args }}
+      k3s server {{ hostvars[joining_master].k3s_server_init_args }}
     creates: "{{ systemd_dir }}/k3s-init.service"
   delegate_to: "{{ joining_master }}"
   no_log: true
-  vars:
-    primary_master: "{{ groups[group_name_master | default('master')][0] }}"
-    primary_master_api: >-
-      {{ hostvars[primary_master].k3s_node_ip | split(',') | first | ansible.utils.ipwrap }}
-    joining_server_args: >-
-      {{ hostvars[joining_master].server_init_args | default('--server https://' +
-      primary_master_api + ':6443 --token ' +
-      (hostvars[joining_master].k3s_token | default(k3s_token)) + ' ' +
-      (hostvars[joining_master].extra_server_args | default(''))) }}
 
 - name: Wait for primary registration of {{ joining_master }}
   ansible.builtin.command:
     cmd: >-
-      {{ k3s_kubectl_binary | default('k3s kubectl') }} get node {{ joining_master }}
+      {{ k3s_kubectl_binary | default('k3s kubectl') }} get node
+      {{ hostvars[joining_master].ansible_hostname }}
   delegate_to: "{{ groups[group_name_master | default('master')][0] }}"
   register: joined_master
   until: joined_master.rc == 0