Using Split and join together in Ansible template file - python-3.x

Question

I want to use hostnames of a group in ansible inventory in a template bash script file.
This is my inventory:
[group_srv]
srv1.co.company
srv2.co.company
srv3.co.company
This is that I wrote in script.sh.j2
for i in '{{ groups['group_srv'][0:3].split('.')[0] | join(' ') }}' ; do
echo $i
done
This is my desired output, but I cannot use split() and join() together.
for i in 'srv1' 'srv2' 'srv3'; do
echo $i
done
Any help is appreciated.

Answer 1

Ansible provides a magic variable containing the short name for each server in your inventory (i.e. the first string before the first dot): inventory_hostname_short
You can access all servers vars in an other magic var: hostvars
You can use the map filter to:
extract values for a list of keys inside a dict (e.g. the relevant hosts for your group in hostvars)
select a single key in a list of dictionaries (e.g. the short inventory name in each extracted server vars).
Those two operations can actually be done at once at extraction time.
Putting it all together:
for i in '{{ groups['group_srv'] | map('extract', hostvars) | map(attribute='inventory_hostname_short') | join("' '") }}' ; do
echo $i
done
Which can be shortened as
for i in '{{ groups['group_srv'] | map('extract', hostvars, 'inventory_hostname_short') | join("' '") }}' ; do
echo $i
done

Answer 2

The declaration below does the job
short_0_3: "{{ groups.group_srv[0:3]|
map('split', '.')|
map('first')|
join(' ') }}"
The next option is the extraction of the variable inventory_hostname_short
short_0_3: "{{ groups.group_srv[0:3]|
map('extract', hostvars, 'inventory_hostname_short')|
join(' ') }}"
Both options give
short_0_3: srv1 srv2 srv3
Example of a complete playbook for testing
- hosts: all
gather_facts: false
vars:
short_0_3: "{{ groups.group_srv[0:3]|
map('split', '.')|
map('first')|
join(' ') }}"
tasks:
- block:
- shell: "for i in {{ short_0_3 }}; do echo $i; done"
register: out
- debug:
var: out.stdout_lines
delegate_to: localhost
run_once: true
shell> cat hosts
[group_srv]
srv1.co.company
srv2.co.company
srv3.co.company
srv4.co.company
srv5.co.company

Answer 3

In Jinja2 loop you can use filters.
{% if not loop.last %} {% endif %} adds a white space after every element except the last one.
for i in {% for host in groups['group_srv'] %}'{{ host.split('.')[0] }}'{% if not loop.last %} {% endif %}{% endfor %} ; do
echo $i
done
Result:
for i in 'test-001' 'test-002' ; do
echo $i
done