Ansible Five random hosts from /etc/ansible/hosts - ansible

Question

I have this playbook, it work using max_index but always takes the first 3 hosts from /etc/ansible/hosts , i need to take 3 random (and not repeated) hosts from that file.
playbook.yml
---
- hosts: ciscos
connection: local
gather_facts: false
tasks:
- group_by: key=limited_selection
when: play_hosts.index(inventory_hostname) < max_index | int
- hosts: limited_selection
gather_facts: no
/etc/ansible/hosts
[ciscos]
stagin ansible_host=10.xx.xx.1
stagin2 ansible_host=10.xx.xx.1
stagin3 ansible_host=10.xx.xx.1
stagin4 ansible_host=10.xx.xx.1
stagin5 ansible_host=10.xx.xx.1

Answer 1

Solution
You need to shuffle the elements of the group and choose three first. The Jinja2 expression for that is:
(groups['ciscos'] | shuffle)[0:3]
Implementation which should work, but has problems
You should be able to simply filter the group in the hosts declaration:
- hosts: "{{ (groups['ciscos'] | shuffle)[0:3] }}"
gather_facts: no
tasks:
- debug:
However the results are undeterministic - although the play shows as running against three randomly chosen hosts, the tasks are sometimes executed on 1, 2, 3, or 0:
PLAY [[u'stagin2', u'stagin4', u'stagin5']] *******************************************************************************
TASK [debug] **************************************************************************************************************
ok: [stagin2] => {
"msg": "Hello world!"
}
ok: [stagin5] => {
"msg": "Hello world!"
}
Workaround (implementation which works)
Use add_host module to create a filtered group:
- hosts: localhost
connection: local
gather_facts: no
tasks:
- add_host:
name: "{{ item }}"
groups: limited_selection
loop: "{{ (groups['ciscos'] | shuffle)[0:3] }}"
- hosts: limited_selection
gather_facts: no
tasks:
- debug:

Answer 2

What about something like this?
---
- hosts: ciscos
gather_facts: False
connection: local
tasks:
- name: Fact My Inventory
set_fact:
myinventory: "{{ ansible_play_batch | shuffle }}"
run_once: True
delegate_to: localhost
- name: Fact limited_selection
set_fact:
limited_selection: "{{ myinventory[0:max_index|int] }}"
run_once: True
delegate_to: localhost
- name: Create Inventory
add_host:
name: '{{ item }}'
groups: limited_selection
with_items: "{{ limited_selection }}"
delegate_to: localhost
- hosts: limited_selection
gather_facts: no
tasks:
- name: Debug
debug:
msg: "I'm in the limited selection group!"
Be careful with play_hosts as it is deprecated.
Note: I have kept the playbook with connection:ciscos instead of localhost for learning purposes and showing the ansible_play_batch and max_index variables. It is better to have a localhost play with groups instead of delegate_to:localhost