Ansible requires python-apt but it's already installed

Question

Prologue: I am just moving first stesp in ansible, so please be patient

Also: I read the answers at 'Ansible demands installing MySQL-python despite it was already installed' but my case is different because locally, on the control machine, is all perfect; thanks to this question I discovered that my problem was in the remote controlled machine. So my questions is the same but the question linked do not contains an answer to resolve my problem.

I'm testing ansible from command line. For example, I succesfully can ping

~/.ssh$ ansible openvpn -C -m "ping"
192.168.1.225 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

I tried to launch an apt update.

I am not sure if this is the right syntax for having the equivalent of apt-get update, but this is not the question

I am using -C to see what ansible says to me when I ask to do a dry run.

$ ansible openvpn -C -m "apt update-cache=yes"
192.168.1.225 | FAILED! => {
    "changed": false,
    "msg": "python-apt must be installed to use check mode. If run normally this module can auto-install it."
}

EDIT : As @Davide Maze suggested, it could be due to missing python-apt. So I checked, but _I have python-apt

$ python -V
Python 2.7.15rc1

$ pip list
... cut ...
python-apt (1.6.2)
... cut ...

$ which python
/usr/bin/python

My question is: why does ansible tell me that python-apt is not installed, and how to fix this?

Answer 1

I solved this error by using ansible_python_interpreter argument while running the ansible-playbook, like below.

ansible-playbook playbook_name.yml -e ansible_python_interpreter=/usr/bin/python --check

Answer 2

Thanks to @David Maze for pointing me to the right direction

I was checking for python-apt in the controller machine, not in the controlled machine.

So I installed the package from the controller into the controlled machine using:

$ ansible openvpn -m "apt name=python-apt state=latest" --become-user realtebo

You can also use the following form, that does sudo apt-get update and wait for operator to enter the password. The user is the one logged in via ssh; so check your config. In my case, I'm using ssh keys; password login is disabled at all.

$ ansible openvpn -m apt -a "update-cache=yes" --become --ask-become-pass

Tip 1: To avoid this interaction is available the vault, but I've not tried it yet.

Tip 2: Also, --ask-become-pass is not in the doc where you're probably looking for, at letter a; this is because the option is shortened in -K, uppercase, so look more down See the doc

After ensuring that remotely the package python-apt is available, then the -C option started to work, exactly because now python-apt is available remotely.

ansible openvpn -C -m "apt name=python state=latest"

192.168.1.225 | SUCCESS => {
    "cache_update_time": 1533077635,
    "cache_updated": false,
    "changed": false
}