Question

This is a long question detailing all that I did from the start. Hope it helps.
I am working on a django application and need to deploy it on to the production server. The production server is a virtual server managed by IT, and I do not have the root access. They have given me rights to manage the installations of my modules in /swadm and /home/swadm.
So I have planned to do create the following arrangement:

• /swadm/etc/httpd/conf where I maintain httpd.conf
• /swadm/etc/httpd/user-modules where I maintain my apache modules (mod_wsgi)
• /swadm/var/www/django/app where I maintain my django code
• /swadm/usr/local/python/2.6 where I will maintain my python 2.6.7 installation with modules like django, south etc.
• /home/swadm/setup where I will be storing the required source tarballs and doing all the building and installing out of.
• /home/swadm/workspace where I will be maintaining application code that is in development.

The system has python2.4.3 and python2.6.5 installed but IT recommended that I maintain my own python installation if I required lot of custom modules to be installed (which I would be).

So I downloaded python2.6.7 source. I needed to ensure python is installed such that its shared library is available. When I ran the configure script with only the option --enable-shared and --prefix=/swadm/usr/local/python/2.6, it would get installed but surprisingly point to the system’s installation of python2.6.5.

$ /swadm/usr/local/python/2.6/bin/python
Python 2.6.5 (r265:79063, Feb 28 2011, 21:55:45)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-50)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

So I ran the configure script following instructions from Building Python with –enable-shared in non-standard location as

./configure --enable-shared --prefix=/swadm/usr/local/python/2.6  LDFLAGS="-Wl,-rpath /swadm/usr/local/python/2.6/lib"

Also making sure I had created the directories beforehand ( as the link suggests) to avoid the errors expected. Now typing /swadm/usr/local/python/2.6/bin/python would start the correct python version 2.6.7. So I moved on to configuring and installing mod_wsgi. I configured it as

./configure --with-python=/swadm/usr/local/python/2.6/bin/python

the Makefile that was created tries to install the module into /usr/lib64/httpd/modules and I have no write permissions there, so I modified the makefile to install into /swadm/etc/httpd/user-modules. (There might be a command argument but I could not figure it out). The module got created fine. A test wsgi script which I used was

import sys

def application(environ, start_response):
    status = '200 OK'
    output = 'Hello World!'
    output = output + str(sys.version_info)
    output = output + '\nsys.prefix = %s' % repr(sys.prefix)
    output = output + '\nsys.path = %s' % repr(sys.path)
    response_headers = [('Content-type', 'text/plain'),
                    ('Content-Length', str(len(output)))]
    start_response(status, response_headers)
    return [output]

And the output shown was, surprisingly

Hello World!(2, 6, 5, 'final', 0)
sys.prefix = '/swadm/usr/local/python/2.6'
sys.path = ['/swadm/usr/local/python/2.6/lib64/python26.zip',    '/swadm/usr/local/python/2.6/lib64/python2.6/', '/swadm/usr/local/python/2.6/lib64/python2.6/plat-linux2', '/swadm/usr/local/python/2.6/lib64/python2.6/lib-tk', '/swadm/usr/local/python/2.6/lib64/python2.6/lib-old', '/swadm/usr/local/python/2.6/lib64/python2.6/lib-dynload']`

So you see somehow the mod_wsgi module still got configured with the system’s python 2.6.5 installation and not my custom one.
I tried various things detailed in the mod_wsgi documentation

• Set WSGIPythonHome in httpd.conf to /swadm/usr/local/python/2.6 and
  WSGIPythonPath to /swadm/usr/local/python/2.6/lib/python2.6

• Created a symlink in the python config directory to point to the libpython2.6.so file

  $ ln -s ../../libpython2.6.so

When I do ldd libpython2.6.so this is what I see:

$ ldd libpython2.6.so
 linux-vdso.so.1 =>  (0x00007fffc47fc000)
 libpthread.so.0 => /lib64/libpthread.so.0 (0x00002b666ed62000)
 libdl.so.2 => /lib64/libdl.so.2 (0x00002b666ef7e000)
 libutil.so.1 => /lib64/libutil.so.1 (0x00002b666f182000)
 libm.so.6 => /lib64/libm.so.6 (0x00002b666f385000)
 libc.so.6 => /lib64/libc.so.6 (0x00002b666f609000)
 /lib64/ld-linux-x86-64.so.2 (0x00000031aba00000)

And ldd mod_wsgi.so gives

$ ldd /swadm/etc/httpd/user-modules/mod_wsgi.so
 linux-vdso.so.1 =>  (0x00007fff1ad6e000)
 libpython2.6.so.1.0 => /usr/lib64/libpython2.6.so.1.0 (0x00002af03aec7000)
 libpthread.so.0 => /lib64/libpthread.so.0 (0x00002af03b270000)
 libdl.so.2 => /lib64/libdl.so.2 (0x00002af03b48c000)
 libutil.so.1 => /lib64/libutil.so.1 (0x00002af03b690000)
 libm.so.6 => /lib64/libm.so.6 (0x00002af03b893000)
 libc.so.6 => /lib64/libc.so.6 (0x00002af03bb17000)
 /lib64/ld-linux-x86-64.so.2 (0x00000031aba00000)

I have been trying re-installing and re-configuring python and mod_wsgi but to no avail. Please let me know where I am going wrong.
(Sorry for the very long post)

TLDR; System with non-root access has default python installation. I am maintaining my own python and python modules. mod_wsgi configured and built with the custom python, still points to the system’s python when I run a test script that prints out the sys version_info and path.

UPDATE:
On Browsing through the stackoverflow (should have done it earlier) I found this answer by Graham Dumpleton on mod_wsgi python2.5 ubuntu 11.04 problem which solved the error for me. Now when I do ldd mod_wsgi.so I see that it is linked to the correct shared library of python. I now installed Django and MySQLdb using my custom python install. And Now I am facing this error:

The following error occurred while trying to extract file(s) to the Python egg
cache:
[Errno 13] Permission denied: '/var/www/.python-eggs'
The Python egg cache directory is currently set to:
/var/www/.python-eggs
Perhaps your account does not have write access to this directory?  You can
change the cache directory by setting the PYTHON_EGG_CACHE environment
variable to point to an accessible directory.

So I did change the value of PYTHON_EGG_CACHE by doing export PYTHON_EGG_CACHE=/swadm/var/www/.python-eggs. but I am still getting the same error. I am investigating more. Will update when I solve this.

Answer 1

Egg cache issue solved by setting environment variable in WSGI script:

http://code.google.com/p/modwsgi/wiki/ApplicationIssues#Access_Rights_Of_Apache_User

or in Apache configuration:

http://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIPythonEggs
http://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIDaemonProcess

Which of latter two is used depends on whether using emebedded mode or daemon mode.