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

Answer 1

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'>

Answer 2

@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:

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

Answer 3

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