Limit nodes in gather ansible_default_ipv4 (#11370)

Signed-off-by: tu1h <lihai.tu@daocloud.io>

roles/kubespray-defaults/tasks/fallback_ips.yml

@@ -3,14 +3,14 @@
 # ansible_default_ipv4 isn't what you think.
 # Thanks https://medium.com/opsops/ansible-default-ipv4-is-not-what-you-think-edb8ab154b10
 
-- name: Gather ansible_default_ipv4 from all hosts
+- name: Gather ansible_default_ipv4 from all hosts or specific hosts
   setup:
     gather_subset: '!all,network'
     filter: "ansible_default_ipv4"
   delegate_to: "{{ item }}"
   delegate_facts: yes
   when: hostvars[item].ansible_default_ipv4 is not defined
-  loop: "{{ (groups['k8s_cluster'] | default([]) + groups['etcd'] | default([]) + groups['calico_rr'] | default([])) | unique }}"
+  loop: "{{ (ansible_play_hosts_all + [groups['kube_control_plane'][0]]) | unique if ansible_limit is defined else (groups['k8s_cluster'] | default([]) + groups['etcd'] | default([]) + groups['calico_rr'] | default([])) | unique }}"
   run_once: yes
   ignore_unreachable: true
   tags: always
@@ -19,7 +19,8 @@
   set_fact:
     fallback_ips_base: |
       ---
-      {% for item in (groups['k8s_cluster'] | default([]) + groups['etcd'] | default([]) + groups['calico_rr'] | default([])) | unique %}
+      {% set search_hosts = (ansible_play_hosts_all + [groups['kube_control_plane'][0]]) | unique if ansible_limit is defined else (groups['k8s_cluster'] | default([]) + groups['etcd'] | default([]) + groups['calico_rr'] | default([])) | unique %}
+      {% for item in search_hosts %}
       {% set found = hostvars[item].get('ansible_default_ipv4') %}
       {{ item }}: "{{ found.get('address', '127.0.0.1') }}"
       {% endfor %}