streamline ansible_default_ipv4 gathering loop (#9281)

roles/kubespray-defaults/tasks/fallback_ips.yml

@@ -4,13 +4,15 @@
 # Thanks https://medium.com/opsops/ansible-default-ipv4-is-not-what-you-think-edb8ab154b10
 
 - name: Gather ansible_default_ipv4 from all hosts
-  tags: always
-  include_tasks: fallback_ips_gather.yml
-  when: hostvars[delegate_host_to_gather_facts].ansible_default_ipv4 is not defined
-  loop: "{{ groups['k8s_cluster']|default([]) + groups['etcd']|default([]) + groups['calico_rr']|default([]) }}"
-  loop_control:
-    loop_var: delegate_host_to_gather_facts
+  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 }}"
   run_once: yes
+  tags: always
 
 - name: create fallback_ips_base
   set_fact:

roles/kubespray-defaults/tasks/fallback_ips_gather.yml

----
-# include to workaround mitogen issue
-# https://github.com/dw/mitogen/issues/663
-
-- name: "Gather ansible_default_ipv4 from {{ delegate_host_to_gather_facts }}"
-  setup:
-    gather_subset: '!all,network'
-    filter: "ansible_default_ipv4"
-  delegate_to: "{{ delegate_host_to_gather_facts }}"
-  connection: "{{ (delegate_host_to_gather_facts == 'localhost') | ternary('local', omit) }}"
-  delegate_facts: yes