How to check whether virtualenv was created with '--no-site-packages'?

Question

Sometimes I get errors that I suspect are the result of my Django app using globally installed Python modules/Django apps instead of those within its virtualenv.

Is there a way to check whether my app's virtualenv was created with '--no-site-packages' without having to delete it, then re-create it as follows?

deactivate
rmvirtualenv my_env
mkvirtualenv my_env --no-site-packages
workon my_env
pip install -r requirements.txt

Surely there must be a better way! Thanks.

Nitriding

Answer 1

There's a file in <env>/lib/pythonX.X/ called no-global-site-packages.txt when you create a virtual environment with --no-site-packages.

Just tried this with virtualenv 1.7:

% virtualenv --no-site-packages env.without
% virtualenv --system-site-packages env.with

% find env.without | sed 's/env.without//' > files.without
% find env.with | sed 's/env.with//' > files.with

% diff files.with*
230a231
> /lib/python3.2/no-global-site-packages.txt

Imprecision

Answer 2

An easy way is opening the interactive python shell and executing import somemodule; print somemodule and then check the path from where that module was imported.

>>> import flask; print flask
<module 'flask' from '/home/xxx/dev/xxx/env/lib/python2.7/site-packages/flask/__init__.pyc'>

vs.

>>> import flask; print flask
<module 'flask' from '/usr/lib64/python2.7/site-packages/flask/__init__.pyc'>

Ethbun

This is valid only if you have the same module installed in both places. You can't really try to import both at the same time (unless you change the pythonpath) – Woodson

If it's not, you'll get an ImportError - depending on where you get it you know that it's only installed at location X. – Ethbun

True if you have the module installed in site-packages. But then you have to select a module which you know it's there and in fact check for ImportError – Woodson

It was an example. Also, __future__ always points to the python's lib folder even if a virtualenv is active. – Ethbun

Answer 3

@Rob's solution is valid for newer versions, I've looked into the code :).

If you have an old one (like my 1.4.5), you can check the python path. If you have the default "site-packages" directory in the path (e.g. /usr/lib/python/site-packages), then your virtualenv was created with site-packages.

You can check it out from something like:

import sys
for p in sys.path:
   if p.find("site-packages") >= 0:
     print (p)

If you had --no-site-packages, all your paths would be like:

/home/user/virtualenv/myenv/lib/python2.6/site-packages/distribute-0.6.10-py2.6.egg
/home/user/virtualenv/myenv/lib/python2.6/site-packages/pip-1.0.2-py2.6.egg
/home/user/virtualenv/myenv/lib/python2.6/site-packages

Otherwise, you'll have something like:

/home/user/virtualenv/myenv/lib/python2.6/site-packages/distribute-0.6.10-py2.6.egg
/home/user/virtualenv/myenv/lib/python2.6/site-packages/pip-1.0.2-py2.6.egg
/home/user/virtualenv/myenv/lib/python2.6/site-packages
/usr/local/lib/python2.6/site-packages

Woodson