How to set an Ansible variable for all plays/hosts?
https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html#fact-caching
As shown elsewhere in the docs, it is possible for one server to reference variables about another, like so:
{{ hostvars['asdf.example.com']['ansible_os_family'] }}
This even applies to variables set dynamically in playbooks.
No sure what you actually want, but you can set a fact for every host in a play with a single looped task (some simulation of global variable):
playbook.yml
---
- hosts: mytest
gather_facts: no
vars:
tasks:
# Set myvar fact for every host in a play
- set_fact:
myvar: "{{ inventory_hostname }}"
delegate_to: "{{ item }}"
with_items: "{{ play_hosts }}"
run_once: yes
# Ensure that myvar is a name of the first host
- debug:
msg: "{{ myvar }}"
hosts
[mytest]
aaa ansible_connection=local
bbb ansible_connection=local
ccc ansible_connection=local
result
PLAY [mytest] ******************
META: ran handlers
TASK [set_fact] ******************
ok: [aaa -> aaa] => (item=aaa) => {"ansible_facts": {"myvar": "aaa"}, "ansible_facts_cacheable": false, "changed": false, "failed": false, "item": "aaa"}
ok: [aaa -> bbb] => (item=bbb) => {"ansible_facts": {"myvar": "aaa"}, "ansible_facts_cacheable": false, "changed": false, "failed": false, "item": "bbb"}
ok: [aaa -> ccc] => (item=ccc) => {"ansible_facts": {"myvar": "aaa"}, "ansible_facts_cacheable": false, "changed": false, "failed": false, "item": "ccc"}
TASK [debug] ******************
ok: [aaa] => {
"msg": "aaa"
}
ok: [bbb] => {
"msg": "aaa"
}
ok: [ccc] => {
"msg": "aaa"
}