QPIP

QPIP is a QGIS plugin allowing to manage Python dependencies for other plugins.

When loading other plugins, it will check if a requirements.txt file exists in its directory. If so, it will verify if the dependencies are met, and display a dialog offering to install missing requirements.

All requirements are installed in the user's profile (under python/dependencies), so that each user profile can have a different set of dependencies.

Usage (end user)

Install QPIP through the QGIS plugin manager. Once installed, by default, dependencies will be checked automatically when activating new plugins.

Plugin menu

A QPIP entry will appear in the plugin menu :

Run dependencies check now : Run the check manually, which opens the main dialog offering to install/upgrade missing requirements.
Show library folder in explorer : Opens the dependencies folder in your profile path. If you run into trouble, you can delete everything contained in that folder to remove everything installed by QPIP.

Main dialog

The main dialog shows a list of Python libraries with the following columns:

Library the name of the Python library
Required by the list of QGIS plugins that require this dependency (dependency met)
Conflicted by the list of QGIS plugins that require this dependency but in an incompatible version (it may still work, but the plugin is likely to fail)
Missed by the list of QGIS plugins that miss this dependency but in an incompatible version (the plugin may partially work, but some features definitely won't)
Installed the version currently available on your system (system-wide python libraries are marked with [global])
Action the action that will be taken once you click on "OK".

You can filter the list to either show only missing/conflicting dependencies, or to include system wide python libraries even if not directly required by a QGIS plugin. Note that you should not uninstall/upgrade system wide python libraries unless you know what you are doing (it may require administrator privileges).

You can also configure when QPIP should automatically check for dependencies.

Usage (how to integrate in your own QGIS plugin)

Add plugin_dependencies=qpip to your plugin's metadata.txt to ensure your user will have QPIP installed upon installation of your plugin.

Add a requirements.txt file in your plugin directory (see an example).

Important : make sure to keep your requirements as loose as possible, as to minimise the risk of requirements conflicts with other plugins. Also, avoid requiring libraries that may conflict with core QGIS dependencies such as GDAL, as it could lead to instabilities.

Limitations

QPIP handles each plugin independently. If two plugins have incomptabile requirements, the user will have to choose which version will be installed, likely breaking the other ones. In such cases, you should contact the plugin authors, and see if they can make their dependencies compatible. Alternatively, you can install each plugin in a different user profile.

How it works internally

QPIP is installed under the a00_qpip directory, so that it (hopefully) loads first
USERPROFILE/python/dependencies/Lib/site-packages is added to sys.path
USERPROFILE/python/dependencies/Scripts is added to the PATH
qgis.utils.loadPlugin is monkeypatched, injecting code that checks requirements in requirements.txt using pkg_resources
if requirements are met, the plugin is loaded directly
if requirements are not met, the dialog is shown to the user*
- on confirmation, selected libraries are installed with pip [...] --prefix USERPROFILE/python/dependencies
- the plugin is then loaded

*during startup (with the Run QPIP on startup option), the dialog is deferred to after GUI initialisation

Contribute

Style is enforced by pre-commit :

pip install pre-commit
pre-commit install

Deployements to QGIS plugin repository are made automatically by Github workflows when tags matching v* are pushed.

Roadmap

automated tests on supported QGIS versions
(long term) integrate functionality in QGIS core

opengisch/qpip