pusimp 0.1.0

Prevent user-site imports

pusimp - prevent user-site imports

pusimp is a python library to prevent user-site imports of specific dependencies of a package. The typical scenario for using pusimp is in combination with a system manager (e.g., apt for Debian), to prevent dependencies from being loaded from user-site instead of the location provided by the system manager.

pusimp is currently developed and maintained at Università Cattolica del Sacro Cuore by Dr. Francesco Ballarin, in collaboration with Prof. Drew Parsons at Università degli Studi di Cagliari.

The acronym

pusimp is an acronym for "prevent user-site imports". However, an internet search reveals that PUSIMP is also a slang term that stands for "Put yourself in my position". In agreement with the slang meaning, pusimp reports an informative (although, arguably, quite long) error message to guide the user towards solving the conflict in their dependencies.

Content

The logic of pusimp is implemented in a single python file, which exposes the function pusimp.prevent_user_site_imports. pusimp can be pip installed from its GitHub repository or from PyPI.

Sample usage

Assume to be the maintainer of a package named my_package, with website https://www.my.package. my_package depends on the auxiliary packages my_dependency_one, my_dependency_two, my_dependency_three, and optionally on my_dependency_four. Furthermore, assume that all five packages are installed by the system manager my_apt at the path /usr/lib/python3.xy/site-packages, and that the four dependencies are available on pypi as my-dependency-one, my-dependency-two, my-dependency-three, and my-dependency-four. The corresponding sample usage in this case is:

import pusimp
pusimp.prevent_user_site_imports(
    "my_package", "my_apt", "https://www.my.package",
    "/usr/lib/python3.xy/site-packages",
    ["my_dependency_one", "my_dependency_two", "my_dependency_three", "my_dependency_four"],
    ["my-dependency-one", "my-dependency-two", "my-dependency-three", "my_dependency_four"],
    [False, False, False, True],
    [
        "Additional message for my_dependency_one.",
        "",
        "",
        "Maybe inform the user that my_dependency_four is optional."
    ],
    lambda dependency_pypi_name, dependency_actual_path: f"pip uninstall {dependency_pypi_name}"
)

Suppose now to have a broken configuration in which my_dependency_one is missing, my_dependency_two is broken, while my_dependency_three and my_dependency_four are installed on the user-site location. A sample error in such case is the following (the terminal will automatically handle line wrapping of long lines):

pusimp has detected the following problems with my_package dependencies:
1) Missing dependencies:
* my_dependency_one is missing. Its expected path was /usr/lib/python3.xy/site-packages/my_dependency_one/__init__.py.
2) Broken dependencies:
* my_dependency_two is broken. Error on import was 'purposely broken'.
3) Dependencies imported from a local path rather than from the path provided by my_apt:
* my_dependency_three was imported from a local path: expected in /usr/lib/python3.xy/site-packages/my_dependency_three/__init__.py, but imported from ~/.local/lib/python3.xy/site-packages/my_dependency_three/__init__.py.
* my_dependency_four was imported from a local path: expected in /usr/lib/python3.xy/site-packages/my_dependency_four/__init__.py, but imported from ~/.local/lib/python3.xy/site-packages/my_dependency_four/__init__.py.

pusimp suggests to apply all of the following fixes:
1) To install missing dependencies:
* check how to install my_dependency_one with my_apt.
2) To fix broken dependencies:
* run 'pip show my-dependency-two' in a terminal: if the location field is not /usr/lib/python3.xy/site-packages consider running 'pip uninstall my-dependency-two' in a terminal, because the broken dependency is probably being imported from a local path rather than from the path provided by my_apt.
3) To uninstall local dependencies:
* run 'pip uninstall my-dependency-three' in a terminal, and verify that you are prompted to confirm removal of files in ~/.local/lib/python3.xy/site-packages/my_dependency_three.
* run 'pip uninstall my_dependency_four' in a terminal, and verify that you are prompted to confirm removal of files in ~/.local/lib/python3.xy/site-packages/my_dependency_four. Maybe inform the user that my_dependency_four is optional.

You can disable this check by exporting the MY_PACKAGE_ALLOW_USER_SITE_IMPORTS environment variable. Note, however, that this may break the installation provided by my_apt.
If you believe that this message appears incorrectly, report this at https://www.my.package .