Python – Debian Lenny, Python 2.7 and mod_wsgi

I am running a Debian Lenny box, which comes with Python 2.5.2. I would like to run Python 2.7 for my WSGI apps only, keeping 2.5 as default for the system, but I cannot get it to work.

First, I installed Python 2.7.2 from source into /usr/local:

Python-2.7.2 # ./configure --enable-shared
[…]
Python-2.7.2 # make
[…]
Python-2.7.2 # make altinstall
[…]

Calling python2.7 now from the command line works without any problems. It also finds packages installed via pip in /usr/local/lib/python2.7/packages.

Next, I built mod_wsgi and copied it manually to the Apache module directory, so as not to touch files placed by apt-get.

mod_wsgi-3.3 # ./configure --with-python=/usr/local/bin/python2.7
[…]
mod_wsgi-3.3 # make
[…]
mod_wsgi-3.3 # cp .libs/mod_wsgi.so /usr/lib/apache2/modules/mod_wsgi.so-2.7
mod_wsgi-3.3 # cd /usr/lib/apache2/modules
modules # ln -sf mod_wsgi.so-2.7 mod_wsgi.so
modules # ldd mod_wsgi.so-2.7
        linux-vdso.so.1 =>  (0x00007fff08f53000)
        libpython2.7.so.1.0 => /usr/local/lib/libpython2.7.so.1.0 (0x00002b0317e1f000)
        libpthread.so.0 => /lib/libpthread.so.0 (0x00002b03181fd000)
        libdl.so.2 => /lib/libdl.so.2 (0x00002b031841a000)
        libutil.so.1 => /lib/libutil.so.1 (0x00002b031861e000)
        libm.so.6 => /lib/libm.so.6 (0x00002b0318821000)
        libc.so.6 => /lib/libc.so.6 (0x00002b0318aa5000)
        /lib64/ld-linux-x86-64.so.2 (0x00002b03179cd000)

I then modified /etc/apache2/mods-available/wsgi.conf and added the following directive:

<IfModule mod_wsgi.c>
    […]
    WSGIPythonHome /usr/local
    […]
</IfModule>

(Of course, wsgi.conf is symlinked in /etc/apache2/mods-enabled.)

Finally, I restarted apache, but my WSGI scripts won’t run. I get the following traceback in Apache’s error log:

mod_wsgi (pid=20746): Exception occurred processing WSGI script '/path/to/script.wsgi'.
Traceback (most recent call last):
  File "/usr/local/lib/python2.5/site-packages/Flask-0.7.2-py2.5.egg/flask/app.py", line 1306, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python2.5/site-packages/Flask-0.7.2-py2.5.egg/flask/app.py", line 1295, in wsgi_app
    return response(environ, start_response)
  File "/usr/local/lib/python2.5/site-packages/Werkzeug-0.6.2-py2.5.egg/werkzeug/wrappers.py", line 1017, in __call__
    start_response(status, headers)
TypeError: expected byte string object for status, value of type str found

I also tried the test WSGI script found in the Installation Issues section of mod_wsgi’s documentation, but I get the same TypeError here. Judging from the traceback, I would guess that Apache now runs Python 2.5 in combination with mod_wsgi compiled for 2.7.

Any ideas?