Introduce support for Archlinux

[michalroxorpl]

I have created a patch to allow installation on Archlinux ansible_os_family
Tested on 4 different hosts (2 Raspberry Pies, one VM and my daily work laptop).

What I dislike is:

• The pacman may complain about conflicts if there will be existing files on filesystem belonging to to-be installed packages. My solution for that is (after manually reviewing changes to be done):

sudo rm -rf $(pacman --noconfirm -S borgmatic | grep : | awk '{print $2}' | xargs)

• On two hosts there was a problem with correct recognition if virtualenv (python -m venv) is in path, it was, but as a symlink, which failed the test. The solution was to make hardlinks, ie:

cd /usr/bin
ln -Pf python3.9 python3
ln -Pf python3 python

Funny thing is on two hosts it worked out of the box, without any necessity for manual intervention.
Besides those two issues everything works like a charm.

Thank you for your great work guys.

[m3nu]

Thanks for the addition! Would it also make sense to test on Arch? If so, you could add an appropriate Docker image there: https://github.com/borgbase/ansible-role-borgbackup/blob/master/molecule/default/molecule.yml#L6

[michalroxorpl]

I will try preparing the Docker image. I have found out a permanent solution for my doubts listed above. Some packages need to be installed not as system packages, but as python setup-tools / pip installed modules. I have tested it on minimal new Arch installation to make sure it will work for everyone. I will create an appropriate PR soon.

[michalroxorpl]

Ok, molecule is something new for me, however I managed to add what I feel is missing to the molecule.yml.
I hope this does the job.

[m3nu]

Yeah, now working on Arch yet. See the test.

fatal: [archlinux-latest]: FAILED! => {"ansible_facts": {}, "changed": false, "failed_modules": {"ansible.legacy.setup": {"ansible_facts": {"discovered_interpreter_python": "/usr/bin/python"}, "failed": true, "module_stderr": "/bin/sh: line 1: /usr/bin/python: No such file or directory\n", "module_stdout": "", "msg": "The module failed to execute correctly, you probably need to set the interpreter.\nSee stdout/stderr for the exact error", "rc": 127, "warnings": ["No python interpreters found for host archlinux-latest (tried ['/usr/bin/python', 'python3.9', 'python3.8', 'python3.7', 'python3.6', 'python3.5', 'python2.7', 'python2.6', '/usr/libexec/platform-python', '/usr/bin/python3', 'python'])"]}}, "msg": "The following modules failed to execute: ansible.legacy.setup\n"}

[michalroxorpl]

Tested with molecule (new thing learned), took 2.5 hours (definitely need a new pc) and works.
Thank you for pointing out everything, that could have been done better.
I hope it can be merged now, after the test workflow completes green.

[m3nu]

All good! Thanks for the contribution! Already merged and put a shout-out on Twitter, since I know we have a bunch of Arch users out there:

https://twitter.com/borg_base/status/1440983268183187457