Crazy behaviour when trying to import python module

Question

I have some problems with a django webapp I want to deploy with Apache mod-wsgi and I've traced them down to this line (the django-tagging module is missing):

[Wed Feb 20 13:08:42 2013] [error] [client 172.19.130.50] ImportError: No module named tagging

Now, here's my output when I try to run pip-python (I'm using CENTOS 6) as root and as the apache user:

[root@app1 site-packages]# pip-python freeze | grep tag
django-tagging==0.3.1
django-taggit==0.9.3

Tagging is installed...

[root@app1 site-packages]# sudo -u apache pip-python freeze | grep tag
django-tagging==0.3.1
django-taggit==0.9.3

Apache user says the same !

[root@app1 /]# python
Python 2.6.6 (r266:84292, Sep 11 2012, 08:34:23)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tagging
>>>

Ok root can import tagging !

[root@app1 /]# sudo -u apache python
Python 2.6.6 (r266:84292, Sep 11 2012, 08:34:23)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tagging
Traceback (most recent call last):
  File "", line 1, in 
ImportError: No module named tagging
>>>

But the apache user cannot !!!!! How can I make this work ????

I've double and triple checked all rights to /usr/lib/python2.6/site-packages/ for django-tagging and they are the same as my other packages.

Update 1: I don't really remember how I did install the django-tagging module - but probably as root since apache cannot install modules globally !

Update 2: Here's the output of martijn-pieters's suggestions:

[root@app1 /]# sudo -u apache python -c 'import sys; print sys.path'
['', '/usr/lib64/python2.6/site-packages/Twisted-12.1.0-py2.6-linux-x86_64.egg', '/usr/lib/python2.6/site-packages/django_cas-2.1.1-py2.6.egg', '/usr/lib64/python26.zip', '/usr/lib64/python2.6', '/usr/lib64/python2.6/plat-linux2', '/usr/lib64/python2.6/lib-tk', '/usr/lib64/python2.6/lib-old', '/usr/lib64/python2.6/lib-dynload', '/usr/lib64/python2.6/site-packages', '/usr/lib/python2.6/site-packages', '/usr/lib/python2.6/site-packages/setuptools-0.6c11-py2.6.egg-info']
[root@app1 /]# python -c 'import sys; print sys.path'
['', '/usr/lib64/python2.6/site-packages/Twisted-12.1.0-py2.6-linux-x86_64.egg', '/usr/lib/python2.6/site-packages/django_cas-2.1.1-py2.6.egg', '/usr/lib64/python26.zip', '/usr/lib64/python2.6', '/usr/lib64/python2.6/plat-linux2', '/usr/lib64/python2.6/lib-tk', '/usr/lib64/python2.6/lib-old', '/usr/lib64/python2.6/lib-dynload', '/usr/lib64/python2.6/site-packages', '/usr/lib/python2.6/site-packages', '/usr/lib/python2.6/site-packages/setuptools-0.6c11-py2.6.egg-info']
[root@app1 /]# sudo -u apache head `which pip-python`
#!/usr/bin/python
# EASY-INSTALL-ENTRY-SCRIPT: 'pip==0.8','console_scripts','pip'
__requires__ = 'pip==0.8'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('pip==0.8', 'console_scripts', 'pip')()
    )
[root@app1 /]# head `which pip-python`
#!/usr/bin/python
# EASY-INSTALL-ENTRY-SCRIPT: 'pip==0.8','console_scripts','pip'
__requires__ = 'pip==0.8'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('pip==0.8', 'console_scripts', 'pip')()
    )

The are exactly the same :(

Update 3: Yes, the apache user can load other modules:

[root@app1 /]# sudo -u apache python
Python 2.6.6 (r266:84292, Sep 11 2012, 08:34:23)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import django
>>> import twisted
>>> import cairo

Update 4: I hate myself. The problem was the access rights of the /usr/lib/python2.6/site-packages/tagging/ directory! They were drw-r--r-- (644) instead of the correct drwxr-xr-x(755) so the apache user could not go inside the directory :(

Everything works fine now, thanks for all the help!

how did you `pip install` it? Did you install as user root or as user apache? Installing as different users gives you different access to modules in pip. — Henrik Andersson, Feb 20 '13 at 11:38
compare `sudo -u apache python -c 'import sys; print sys.path'` with `python -c 'import sys; print sys.path'`, and `sudo -u apache head \`which pip-python\`` with `head \`which pip-python\`` perhaps? — Martijn Pieters, Feb 20 '13 at 11:44
Can you import other modules ? also read [surviving nix permissions](http://blog.yourlabs.org/post/19240900759/survive-linux-nix-permissions) — jpic, Feb 20 '13 at 11:53
Can I do something to leave this question unanswered ? Should I close it ? — Serafeim, Feb 20 '13 at 12:28
If you got your answer in comments, just ask the author to create an answer out of it. Otherwise if you didn't solved the problem keep it open. Maybe answering the question asked in comments can help you to solve the problem ;-). — Mauro Rocco, Mar 07 '13 at 09:05

score 2 · Answer 1 · answered Mar 15 '13 at 11:25

I have experienced something similar to this behaviour and ended up adding to Django wsgi.py file the exact path of modules to be imported:

import sys
PACKAGES ='/usr/local/lib/python2.6/dist-packages/'
sys.path.append(PACKAGES + 'django_compressor-1.1.1-py2.6.egg')

Hope it helps.

Who is to blame? not sure, maybe apache or maybe mod_wsgi. This happened to me in an apache2 from Ubuntu 10.04. Recents setups in apache2 from Debian stable and testing never needed to sys.path.append anymore.

Crazy behaviour when trying to import python module

1 Answers1