Run it with
$ pyenv exec ansible-playbook site.yml -i hosts
and you'll get something like
TASK [debug] ****************************************************************************************
ok: [localhost] => {
"groups": {
"all": [
"192.168.0.1",
"192.168.0.2",
"localhost"
],
"appservers": [
"192.168.0.2"
],
"control": [
"localhost"
],
"databases": [
"192.168.0.1"
],
"ungrouped": []
}
}