One of my play is running on group nodes in a cluster and im setting a variable based on certain condition like set a variable as “Master” when a node is master with in the cluster.

- name: Determine master node in the cluster
  hosts: cluster
  gather_facts: no
  tasks:
   - name: Get the Master node hostname
     shell: <command> 
     register: host_info

   set_fact: 
      master_node: {{ host_info.stdout }}
   when: host_info has "master".            #Sample when condition to understand

Im need to access the host_info master_node variable from other host

- name: Add async standby node
  hosts: new_node
  become: yes
  tasks:
   - debug:
       var: hostvars[item]['master_node']
     loop: "{{ groups['cluster'] }}"

Inventory:

[cluster]
cluster_01
cluster_02
[new_node]
new_node_01

when i execute this the debug task shows

TASK [debug] *********************************************************************************************************************************************************************************
ok: [new_node_01] => (item=cluster_01) => {
    "ansible_loop_var": "item",
    "hostvars[item]['primary_node']": "cluster_01",
    "item": "cluster_01"
}
ok: [new_node_01] => (item=cluster_02) => {
    "ansible_loop_var": "item",
    "hostvars[item]['primary_node']": "VARIABLE IS NOT DEFINED!",
    "item": "cluster_02"
}

How can we access only the loop item which is defined?