Set ansible_python_interpreter to python3 on debian (fix error with mitogen)

[floryut]

What type of PR is this?
/kind bug

What this PR does / why we need it:
When mitogen is enable, ubuntu CI fails

Which issue(s) this PR fixes:
None

Special notes for your reviewer:
None

Does this PR introduce a user-facing change?:

NONE

[Miouge1]

I wonder if we have clear requirement for Python 3? Or is that clear now that Python 2 is EOL?

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: floryut, Miouge1

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[floryut]

I wonder if we have clear requirement for Python 3? Or is that clear now that Python 2 is EOL?

/approve

Not sure but as we check and install python3 if not already present, I think we are safe with this, otherwise we could ln -s without forcing to be sure we have a python command existing using python2 or 3

[oomichi]

Or is that clear now that Python 2 is EOL?

Python foundation says Python 2 has been unsupported since January 1, 2020 as https://www.python.org/doc/sunset-python-2/
In addition there is a similar approach in Kubernetes community like kubernetes-sigs/image-builder#249
Then

/lgtm

[oomichi]

I'd like to see this backport for release-2.14 because I confirmed this fixes the following issue on my Ubuntu 18.04 machine:

TASK [bootstrap-os : Install dbus for the hostname module] ******************************************************************************************************************
fatal: [ubuntu]: FAILED! => {"changed": false, "module_stderr": "/bin/sh: 1: /usr/bin/python: not found\n", "module_stdout": "", "msg": "The module failed to execute correct

NO MORE HOSTS LEFT **********************************************************************************************************************************************************

PLAY RECAP ******************************************************************************************************************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
ubuntu                     : ok=8    changed=2    unreachable=0    failed=1    skipped=27   rescued=0    ignored=0   

[floryut]

I'd like to see this backport for release-2.14 because I confirmed this fixes the following issue on my Ubuntu 18.04 machine:

TASK [bootstrap-os : Install dbus for the hostname module] ******************************************************************************************************************
fatal: [ubuntu]: FAILED! => {"changed": false, "module_stderr": "/bin/sh: 1: /usr/bin/python: not found\n", "module_stdout": "", "msg": "The module failed to execute correct

NO MORE HOSTS LEFT **********************************************************************************************************************************************************

PLAY RECAP ******************************************************************************************************************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
ubuntu                     : ok=8    changed=2    unreachable=0    failed=1    skipped=27   rescued=0    ignored=0   

Care to submit the backported PR ?

[oomichi]

Care to submit the backported PR ?

Yes, I did it on #6744