/usr/bin/python3 not found when using pyenv

[markfaine]

[bean @ p-msfc-enms-cm ../run/ansible-playbook] [master] $ ansible-playbook --limit=p-msfc-ils-logagg3.cso.nasa.gov playbooks/openscap.yml 
ERROR! Unexpected Exception, this is probably a bug: [Errno 2] No such file or directory: '/usr/bin/python3': '/usr/bin/python3'
the full traceback was:

Traceback (most recent call last):
  File "/home/bean/.pyenv/versions/venv-3.6.9/bin/ansible-playbook", line 92, in <module>
    mycli = getattr(__import__("ansible.cli.%s" % sub, fromlist=[myclass]), myclass)
  File "/home/bean/.pyenv/versions/3.6.9/envs/venv-3.6.9/lib/python3.6/site-packages/ansible/cli/__init__.py", line 25, in <module>
    from ansible.parsing.dataloader import DataLoader
  File "/home/bean/.pyenv/versions/3.6.9/envs/venv-3.6.9/lib/python3.6/site-packages/ansible/parsing/dataloader.py", line 17, in <module>
    from ansible.module_utils.basic import is_executable
  File "/home/bean/.pyenv/versions/3.6.9/envs/venv-3.6.9/lib/python3.6/site-packages/ansible/module_utils/basic.py", line 74, in <module>
    import selinux
  File "/home/bean/.pyenv/versions/3.6.9/envs/venv-3.6.9/lib/python3.6/site-packages/selinux/__init__.py", line 104, in <module>
    check_system_sitepackages()
  File "/home/bean/.pyenv/versions/3.6.9/envs/venv-3.6.9/lib/python3.6/site-packages/selinux/__init__.py", line 93, in check_system_sitepackages
    system_sitepackages = get_system_sitepackages()
  File "/home/bean/.pyenv/versions/3.6.9/envs/venv-3.6.9/lib/python3.6/site-packages/selinux/__init__.py", line 83, in get_system_sitepackages
    "import json, site; print(json.dumps(site.getsitepackages()))",
  File "/home/bean/.pyenv/versions/3.6.9/lib/python3.6/subprocess.py", line 356, in check_output
    **kwargs).stdout
  File "/home/bean/.pyenv/versions/3.6.9/lib/python3.6/subprocess.py", line 423, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/home/bean/.pyenv/versions/3.6.9/lib/python3.6/subprocess.py", line 729, in __init__
    restore_signals, start_new_session)
  File "/home/bean/.pyenv/versions/3.6.9/lib/python3.6/subprocess.py", line 1364, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: '/usr/bin/python3': '/usr/bin/python3'

I'm using pyenv. I did try to edit it to change the system python to /usr/bin/python, I got no errors but it just failed to work.

My python is: ~/.pyenv/versions/venv-3.6.9/bin/python3 version 3.6.9
I have selinux loaded in my virtual env:

[bean @ p-msfc-enms-cm ../versions/venv-3.6.9/bin] [master] $ pip list | grep selinux
selinux             0.2.1

[ssbarnea]

I am afraid that pyenv is not supported and I do not know a way to make it work, basically you need to build selinux bindings from source and install them, something that is not done by this extension.

I think that this also means that you cannot really use ansible from a pyenv environment on selinux enabled systems. I may be wrong but this needs to be confirmed with ansible core team.

[beenje]

I have the same issue when running ansible-lint from inside a conda environment.
selinux is disabled on that server (CentOS 7):

$ sudo getenforce
Disabled

Is the libselinux-python3 package still required to detect that?

[ssbarnea]

AFAIK yes and also ansible would fail. So is not so much about if you have selinux enabled or not, whenver is available, ansible would ask about missing bindings.

[beenje]

Are you really sure about that? I've been running tests on several gitlab-runners (CentOS 7) with molecule. When we switched from Python 2 to Python 3 for Ansible, I had issues because there were no libselinux-python3 RPM for CentOS 7 at the time. Disabling selinux fixed the problem (it was in permissive mode before). I've been running tests successfully with ansible 2.9.11, ansible-lint 4.2.0, molecule 2.22 without bindings.

It's when upgrading to molecule 3.0.8 and ansible-lint 4.3.0 that I got an issue again and was forced to install libselinux-python3.

[ssbarnea]

You did not search well enough, the python3 library rpm is called python3-libselinux and is available from the default repositories.

[beenje]

You did not search well enough, the python3 library rpm is called python3-libselinux and is available from the default repositories.

$ yum search libselinux
...
libselinux-python.x86_64 : SELinux python bindings for libselinux
libselinux-python3.x86_64 : SELinux python 3 bindings for libselinux
...

I know it is available now. My point was that it wasn't at the time we switched to Python 3, but I could make ansible work. I think you are the one that opened this issue: https://bugs.centos.org/view.php?id=16389

[ssbarnea]

Yes, I did. It was fixed after I lost hope. Lots of things changed in regards to python3 and centos-7, as some unprecedented backporting of python3.6 occurred in 7.8 -- a very useful move as it allows people to switch from py2 to py3 without having to also switch the entire operating system.