Some pointers on installing mod_wsgi on Windows

Recently I needed to install mod_wsgi in a Windows box and this proved to be a little bit tricky. Granted this was a different base installation from the one recommended by the mod_wsgi developer and I’m not really a Windows user, but I thought this might help someone with the same issues.

If you can choose the Apache httpd distribution to install, just use the one from Apache Lounge (https://apachelounge.com). Is the one recommended in the mod_wsgi readme and the easiest one to build the package for. In my case I needed to install mod_wsgi onto an already running instance of Apache httpd.

The installation reflected in this post is a 32 bit one. Use the appropriate packages accordingly. Don’t mix different architechture packages.

Install python

Download the python installer from https://www.python.org/downloads/windows/ and execute it. Make sure that it’s being installed for all users (it will install to C:\Program Files\Python), you might need to use the “Customize installation” option.

Once the process is done open a prompt and try running the following commands.

python -V
pip -V

It should print both the version of the python interpreter and the python installer.

Install the Visual C++ compiler

Download and install “Build tools for Visual Studio” from https://visualstudio.microsoft.com/downloads/

Note that the “Visual C++ redistributable package” installs just the runtime components. For this we need the build tools package.

For more information check https://wiki.python.org/moin/WindowsCompilers

Upgrade setuptools

Open a command prompt and run:

pip install --upgrade setuptools

Install mod_wsgi

If the Apache httpd instance is installed in a path other than C:\Apache\Apache24 (Apache Lounge’s default installation path) the MOD_WSGI_APACHE_ROOTDIR environment variable will need to be set. In this case I had to set it to the following path C:\Program Files (x86)\Apache Software Foundation\Apache

From within a command prompt run:

pip install mod_wsgi

If everything is alright it should just display a message announcing that the package has been installed.

In my case it threw an error complaining about missing files in the include directory. This directory contains the headers needed for compiling the mod_wsgi module. This Apache httpd installation lacked some files and contained a few extra ones when compared with an Apache Lounge release installed in a test box. This issue was solved by copying the files from the Apache Lounge release and running again the mod_wsgi install command. If you need to do this, make sure that the major and minor versions of Apache httpd match.

Configure mod_wsgi

After installing the mod_wsgi package some configuration is needed.

In order to obtain the proper paths for we need to run the following command:

mod_wsgi-express module-config

It should return an output like:

LoadFile "c:/program files (x86)/python37-32/python37.dll"
LoadModule wsgi_module "c:/program files (x86)/python37-32/lib/site-packages/mod_wsgi/server/mod_wsgi.cp37-win32.pyd"
WSGIPythonHome "c:/program files (x86)/python37-32"

This output will then need to be copied in the conf/httpd.conf file or other relevant configuration file in the Apache httpd installation folder.

Upon restarting Apache httpd the server control window should now display a new item in the status bar that reads “mod_wsgi”.

This should be enough to run a WSGI app with the module.

Testing it all

Create a new python file (C:\WSGIAppDir\wsgi_app.py) with the following content.

def wsgi_app(environ, start_response):
    output = b'It Works!'
    status = '200 OK'
    headers = [('Content-type', 'text/plain'),
               ('Content-Length', str(len(output)))]
    start_response(status, headers)
    return output

Add a new section to the apache configuration, either in a new vhost configuration file or at the end of httpd.conf with the following content:

<IfModule wsgi_module>
    WSGIScriptAlias /test-wsgi/ "C:/WSGIAppDir/wsgi_app.py"
    <Directory "C:/WSGIAppDir">
        AllowOverride None
        Options None
        Order deny,allow
        Allow from all
    </Directory>
</IfModule>

Notice the forward slashes in the directories instead of the MS Windows traditional backward slashes.