Ansible vars_files

gistfile1.txt

Bootstrap:

mkdir -p vars/bar
touch vars/bar/all.yml

./hosts content:

[test]
localhost
[all:vars]
somevar=bar


test.yml play:

- name: Foo
  hosts: all
  vars_files:
   - "vars/{{ somevar }}/all.yml"
  tasks:
   - debug: var=somevar


Result with -vvv:

skipping vars_file 'vars/{{ somevar }}/all.yml' due to an undefined variable