mod_wsgi: ImportError: No module named 'encodings'

Question

I'm using Apache 2.2.15 on CentOS 6.5. I'm trying to set up a Django app using mod_wsgi. I'm using a virtual environment, and mod_wsgi was configured with --with-python=/path/to/virtualenv/bin/python3.4.

I've added this to my httpd.conf:

WSGIPythonPath /srv/myproject:/path/to/virtualenv/lib/python3.4/site-packages
WSGIPythonHome /path/to/virtualenv
<VirtualHost *:80>
WSGIScriptAlias / /srv/myproject/myproject/wsgi.py
...
</VirtualHost>

In wsgi.py, I added

sys.path.insert(1, "/path/to/virtualenv/lib/python3.4/site-packages")

The problem is that when I try to open the app in my browser, it loads indefinitely. Here's the Apache error log:

Fatal Python error: Py_Initialize: Unable to get the locale encoding
ImportError: No module named 'encodings'
[Mon Jun 30 17:37:28 2014] [notice] child pid 19370 exit signal Aborted (6)
[Mon Jun 30 17:37:28 2014] [notice] child pid 19371 exit signal Aborted (6)
...
[Mon Jun 30 17:37:28 2014] [notice] child pid 19377 exit signal Aborted (6)
Fatal Python error: Py_Initialize: Unable to get the locale encoding
ImportError: No module named 'encodings'

What's interesting is that in both the system installation of Python (2.6) and the virtual environment version (3.4), import encodings works fine! I've tried using the example WSGI script from the mod_wsgi CheckingYourInstallation page to confirm which version of Python is being used by Apache, but I get the same ImportError.

Does anyone have a suggestion for next steps? I've scoured the docs but I don't know where to go from here.

Answer 1

So with some help with my friends (IE: SysAdmins), we got this figured out last night. I learn best by example, so let's assume you're running Apache with mod_wsgi as Linux group apache with user flipperpa. Let's assume you're hosting in /home/my_project with wsgi.py in my_project/wsgi.py.

At the top level (ls -l /):

drwxr-xr-x.  47 root root  4096 Jul  9 09:43 home

In the home directory (ls -l /home):

drwxrwsr-x   7 flipper        apache 4096 Jul 29 10:22 my_project

This was the key. The lower case "s" means the apache group's setgid bit is set, and the execute bit is set. The final "x", of course, means anyone can execute.

Check your permissions down the tree; this did the trick for us.

Answer 2

The issue was caused by SELinux. What I did was this:

• moved the project files into /home/admin/myproject
• changed permissions as in FlipperPA's answer
• and, crucially I think, set the httpd_enable_homedirs SELinux boolean to on using setsebool -P httpd_enable_homedirs on.

The SELinux guide on the CentOS wiki was very helpful. For example, to debug you can run setenforce Permissive so SELinux won't enforce its rules, but still write to the log. Just remember to setenforce Enforcing again afterwards!

Answer 3

On Windows, I solved this problem by putting the Lib directory of my Python installation directly on the PYTHONPATH. This is necessary even though, if you run Python directly in the same shell, it doesn't require this to find the encodings package:

set PYTHONPATH=C:\WinPython-64bit-3.4.4.6Qt5\python-3.4.4.amd64\Lib;%PYTHONPATH%
c:\apache24\bin\httpd.exe

Also be sure to use the correct mod_wsgi version. I downloaded mine from the Unofficial Binaries page and chose it to match the Python (64 bit 3.4 in the example above). My website works correctly with Python after the above change to the .bat file starting Apache.

Note my version of Python, WinPython, is installed by unzipping the install and placing it in the C: drive. Thus is it not installed in the Registry in the usual Windows way, which should minimize Registry interaction considerations.