If you fully automate an IT infrastructure you sometimes need the individual IP addresses of each host of an host group. For example when you configure a loadbalancer or a reverse proxy and need to enter the IP addresses of the group of webservers when you cannot rely on DNS names.
The following Ansible playbook delegates the gather_facts to those webservers and iterates over their IP addresses.
---
- hosts: loadbalancers
tasks:
- name: delegate update_facts
setup:
delegate_to: '{{ item }}'
delegate_facts: yes
with_items: '{{ groups["linux_webservers"] }}'
when: hostvars[item]["ansible_default_ipv4"]["address"] is not defined
- name: print ansible_all_ipv4_addresses
debug:
msg: '{{ hostvars[item]["ansible_hostname"]}}: {{ hostvars[item]["ansible_default_ipv4"]["address"] }}'
with_items: '{{ groups["linux_webservers"] }}'
Sample Inventory
[loadbalancers]
lb01
[linux_webservers]
web01
web02
web03