Use looseversion in place of distutils

[freyes]

(cherry picked from commit 012b2d6)

[freyes]

Blocker for s390x validation

[freyes]

how does this work when being used in a classic charm?

[ajkavanagh]

Based on your comment above, it probably breaks unless the parent charm ensures that the package is installed.

[freyes]

shouldn't this be more like:

try:
    from distutils.version import LooseVersion
except ImportError:
    try:
        # reactive charm path, where the venv already has this package
        from looseversion import LooseVersion
    except ImportError:
        # classic charm code path where python packages are installed via apt-get
        apt_install(['python3-looseversion'], fatal=True)
        from looseversion import LooseVersion

[ajkavanagh]

I really don't like this pattern where charmhelpers runs apt_install; I'd much rather the parent charm resolved the dependencies and installed python3-looseversion where necessary; (which might be all of them in the future). It makes unit testing harder when apt_install() is at module load time.

[ajkavanagh]

I really don't like this pattern where charmhelpers runs apt_install; I'd much rather the parent charm resolved the dependencies and installed python3-looseversion where necessary; (which might be all of them in the future). It makes unit testing harder when apt_install() is at module load time.

[ajkavanagh]

Based on your comment above, it probably breaks unless the parent charm ensures that the package is installed.

[ajkavanagh]

Holding off merging whilst @freyes conversation is concluded; there may be further changes needed to the original commits.