Create vars from host inventory - ansible

Question

I have below infrastructure (3 servers running windows 2016 server edition) where master server runs a IIS service on port 80(example) and 2 agents need to connect to them. To allow the communication, I need to add windows firewall rules to whitelist the ip addresses
one master server (mas)
and two agent servers (agt)
The task which I need to execute through ansible is, I need to add the below firewall rule only on the master server and should not run on the agent hosts. How to run the below task only on the master server so that the ip address details of agent(agt) machines are used while configuring the firewall rules.
- hosts: mas, agt
tasks:
- name: Firewall Rule Modifications
win_firewall_rule:
name: "IIS port"
localport: "80"
direction: in
action: allow
remoteip: "{{ansible_ip_addresses[0]}}"
protocol: "tcp"
description: "Allow agents"
enabled: yes
state: present

Answer 1

I was able to create a solution(with a vagrant test setup with centos 7) as mentioned below but I think there should be a simpler way to achieve this :-)
Inventory File:
[master]
mas
[agents]
agt1
agt2
Playbook:
- name: Configure Iptables
hosts: all
serial: 1
tasks:
- name: create a file to store inventory IP's
file:
dest: /tmp/foo
state: touch
force: yes
delegate_to: localhost
- name: Register IP address
shell: echo "{{ ansible_enp0s8.ipv4.address }}"
register: op
delegate_to: localhost
- name: write IP's to a temp file
lineinfile:
dest: /tmp/foo
line: "{{ op.stdout_lines[0] }}"
insertafter: EOF
delegate_to: localhost
- name: Add firewall rules
iptables:
chain: INPUT
source: "{{item}}"
protocol: tcp
destination_port: 80
jump: ACCEPT
with_lines: cat /tmp/foo
when: ansible_hostname == 'mas'