WIP: add pipx support

[karolzlot]

This is attempt to add pipx support. Pipx is is great tool to install many packages, I want to use it to install for example docker-compose and docker-auto-labels on hosts.

---

I have problem, which I can't understand how to fix. I can't run pipx from pyinfra, but I can run it from manual ssh session. It works ok if pipx is installed via apt, but version in apt is very outdated.

Example code below generates error:

from pyinfra.api import Config
from pyinfra.operations import apt, pip, pipx

apt.packages(
    name='Ensure python is installed',
    packages=['python3-pip', 'python3-venv'],
    latest=True,
    sudo=True,  # use sudo when installing the packages
    update=True,
    cache_time=3600,
    upgrade=True,
)

pip.packages(
    name="Ensure pipx is installed",
    packages=["pipx"],
    pip="pip3",
    latest=True,
    # sudo=True,  # If sudo is enabled here, then error vanishes, but sudo is not recommended for pip
)

pipx.packages(
    name="Ensure pycowsay is installed",
    packages=["pycowsay"],
    latest=True,
)

Error message:

--> Starting operation: Ensure pycowsay is installed
[REDACTED_IP] >>> sudo -H -n sh -c 'pipx install pycowsay'
[REDACTED_IP] sh: 1: pipx: not found
    [REDACTED_IP] Error
No hosts remaining!
--> pyinfra error: 

[karolzlot]

Another issue is that pipx needs separate commands, it won't work with:

pipx install pycowsay copier docker-compose

It needs:

pipx install pycowsay 
pipx install copier
pipx install docker-compose

I'm not sure if ensure_packages is able to work this way.

[karolzlot]

Problem is pyinfra uses sh -c ' command.... ' to execute commands and $PATH is different because of it. I would like to have an option to use bash instead of sh.

Those commands give interesting, different results:

echo $PATH
sh -c 'echo $PATH'
sudo sh -c 'echo $PATH'

[karlicoss]

For multiple packages issue, here's the related pipx issue pypa/pipx#88