How to access QGIS module from my virtualenv

Question

I am running an Ubuntu 14.4 and I have installed a python virtual environment. Then I pip installed several python libraries (gdal, lxml, psycopg2 etc.)

Also in my system I have the module for QGIS. So when I type python then I can import this module as:

import qgis.core

But when I try to do the same through my virtualenv I get an error: module not found.

When I created the virtualenv I did with the option:

virtualenv --no-site-packages env

Which restricts my env from the system's env. The question is how to access QGIS module in my virtualenv?

Answer 1

After create and activate your virtualenv :

virtualenv --no-site-packages env
source env/bin/activate
pip install [your libs]

You have to defined the PYTHONPATH environnement variable to your QGIS's python installation path.

please change [qgispath] to your qgis's path :

export PYTHONPATH=/[qgispath]/share/qgis/python

it will also be necessary to set LD_LIBRARY_PATH

export LD_LIBRARY_PATH=/[qgispath]/lib

to prevent this error

>>> import qgis.core
ImportError: libqgis_core.so.1.5.0: cannot open shared object file: No such file or directory

Your pythonpath is set only for the virtualenv, and for your session. If you want to set it automatically under this virtualenv, you can create a file under env/lib/python2.7/site-packages with a .pth file.

The most convenient way is to add a path configuration file to a directory that’s already on Python’s path, usually to the .../site-packages/ directory. Path configuration files have an extension of .pth, and each line must contain a single path that will be appended to sys.path. (Because the new paths are appended to sys.path, modules in the added directories will not override standard modules. This means you can’t use this mechanism for installing fixed versions of standard modules.) source

to create and populate the file use a command like that :

cat > [yourVirtualEnv]/lib/python2.7/site-packages/qgispythonpath.pth << /[qgispath]/share/qgis/python

Found in Python Qgis cookbook, and a related answer set pythonpath