Update 2008Feb11:

From rather obscure comment from ‘apt-cache show python-flup’ on a Debian system, I discovered that flup has been superseded by http://www.modwsgi.org/. It is probably worth checking out mod_wsgi instead of mod_fcgid for Python web applications. Based on the documentation for mod_wsgi integration with Django, I am planning on switching. I will post my results in a future post.

Required Software

• Apache 2 – http://httpd.apache.org/
• mod_rewrite – (comes with Apache2)
• mod_fcgid – http://fastcgi.coremail.cn/
• flup – http://trac.saddi.com/flup

mod_fcgid

Download Source and Install

• Download

For reference, here is the mod_fcgid INSTALL.txt… see my Mac OS X notes below it for changes required to get it working on Mac OS X 10.5 (Leopard):

NOTE: This module is for Apache2 ONLY

UNIXIt's tested on my RedHat8 and Solaris. But it should work on other *NIX platform.NOTE: This module MUST run on share memory supported system

1. If your Apache2 installation isn't in /usr/local/apache2, please edit Makefile and correct it2. cd $mod_fcgid_dir3. make   //in Mac you need Xcode tools, optional install on Install CD4. make install5. add the following line in httpd.conf

LoadModule fcgid_module modules/mod_fcgid.so

MAC OS X Notes

• In Mac OS X Leopard, the Makefile needs to be changed from /usr/local/apache2 to /usr/share/httpd, then steps 3 and 4 above should work.
• Step 4 requires: sudo make install
• Step 5, you need to add the following to /etc/apache2/httpd.conf: LoadModule fcgid_module libexec/apache2/mod_fcgid.so
• IMPORTANT: apache 2 on Mac OS X Leopard is 64-bit and by default, the make file does not build the 64-bit module. To do this, you need to add the following to the Makefile after the EXTRA_CFLAGS option (too far above that will cause it not to work apparently):

CFLAGS = -arch ppc -arch ppc64 -arch i386 -arch x86_64

The above will make a universal binary for all Mac OS X.

If at some point, you get this message either in the error_log or by running ‘apachectl configtest’

httpd: Syntax error on line 117 of /private/etc/apache2/httpd.conf: Cannot load/usr/libexec/apache2/mod_fcgid.so into server:dlopen(/usr/libexec/apache2/mod_fcgid.so, 10): no suitable image found.Did find: /usr/libexec/apache2/mod_fcgid.so: mach-o, but wrong architecture

Then your mod_fcgid.so module probably was not built with x86_64 architecture… To check, type

file /usr/libexec/apache2/mod_fcgid.so

And it should list the architectures that the mod_fcgid.so was built for.

Enable mod_fcgid

Linux

At least with Debian/Ubuntu you can enable fcgid by typing (as root):

a2enmod fcgid

Mac OS X Leopard (10.5)

Add the following to /etc/apache2/httpd.conf:

AddHandler    fcgid-script .fcgiSocketPath    /tmp/fcgid_sockSharememPath  /tmp/fcgid_shmIPCConnectTimeout 20

mod_rewrite

We need to tell apache for what urls it should pass off the request to the fcgi script. This is accomplished with mod_rewrite which is normally turned on by default w/ apache 2 (at least the installations I have seen).

We’ll start with the full setup required for gaworkflow.frontend, but test it with a “Hello World” style dispatch.fcgi script.

gaworkflow.frontend apache2 mod_rewrite setup

Linux

Add the following to your apache2 /etc/apache2/sites-available/default or other vhost specific file:

# Enable access to the django admin mediaAlias /media /usr/lib/python2.5/site-packages/django/contrib/admin/media

# Turn on the rewrite engineRewriteEngine on

# Enable http:///admin/ and related urlsRewriteRule ^/admin(.*)$ /usr/lib/cgi-bin/dispatch.fcgi/admin$1 [QSA,L]RewriteRule ^/logout(.*)$ /usr/lib/cgi-bin/dispatch.fcgi/logout$1 [QSA,L]RewriteRule ^/login(.*)$ /usr/lib/cgi-bin/dispatch.fcgi/login$1 [QSA,L]

Mac OS X Leopard

Add the following to your apache2 /etc/httpd.conf:

# Enable access to the django admin media# NOTE: the following did not work for me... I had to copy the media directory to#    /Library/WebServer/Documents/media#Alias /media /System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/django/contrib/admin/media/

# Turn on the rewrite engineRewriteEngine on

# Enable http:///admin urlsRewriteRule ^/eland_config(.*)$ /Library/WebServer/CGI-Executables/dispatch.fcgi/eland_config$1 [QSA,L]RewriteRule ^/admin(.*)$ /Library/WebServer/CGI-Executables/dispatch.fcgi/admin$1 [QSA,L]RewriteRule ^/logout(.*)$ /Library/WebServer/CGI-Executables/dispatch.fcgi/logout$1 [QSA,L]RewriteRule ^/login(.*)$ /Library/WebServer/CGI-Executables/dispatch.fcgi/login$1 [QSA,L]

Restart Apache 2

Linux (Debian/Ubuntu)

sudo /etc/init.d/apache2 restart

Mac OS X Leopard

sudo apachectl restart

dispatch.fcgi

Hello World Test

Now to test that we have the mod_fcgid setup properly, create a file called dispatch.fcgi:

#!/usr/bin/python

def myapp(environ, start_response): start_response('200 OK', [('Content-Type', 'text/plain')]) return ['Hello World!\n']

if __name__ == '__main__': from flup.server.fcgi import WSGIServer WSGIServer(myapp).run()

And move it to your cgi-bin directory:

Linux cgi-bin

sudo mv dispatch.fcgi /usr/lib/cgi-bin/

Mac OS X Leopard cgi-bin

sudo mv dispatch.fcgi /Library/WebServer/CGI-Executables/

Linux/Mac OS X File Permissions

sudo chmod a+x /dispatch.fcgi

Mac OS X 10.5 users will need to update the Options for to include +ExecCGI… by default it is set to “Options None”. The updated entry should look like:

 AllowOverride None Options +ExecCGI Order allow,deny Allow from all

WARNING: You will get a message saying “Forbidden” in the web browser if you do not update the directive above.

Web Browser Test

Point your web browser to http://localhost/admin/ and you should see if it prints “Hello World!”. If you see “Hello World!” continue to the next section.

Installing the Django App dispatch.fcgi script

copy of mydjangoapp code

Make a copy of the mydjangoapp code and database and put it in a location that will be the “live” version of the code/database. On Mac OS X, I choose /Library/WebServer/mydjangoapp. Initialize the database like your normally would, but you will need to update the settings.py module so that DATABASE_NAME is an absolute path, otherwise you will get errors in the apache 2 error_log saying that the python code could not connect to the database. Assuming you also choose /Library/WebServer/mydjangoapp, your DATABASE_NAME variable in settings.py should be:

DATABASE_NAME = '/Library/WebServer/mydjangoapp/mydjangoapp.db'

You will also need to update the settings.py TEMPLATE_DIRS to be an absolute path (relative paths don’t work for some reason) of “/Library/WebServer/gaworkflow/templates”… so the update version should look like:

TEMPLATE_DIRS = ( "/Library/WebServer/mydjangoapp/templates",)

Also, you will need to make a link to the admin templates in our /Library/WebServer/mydjangoapp/templates directory by typing:

Mac OS X 10.5:

ln -s /System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/django/contrib/admin/templates/admin /Library/WebServer/mydjangoapp/templates/adminln -s /System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/django/contrib/admin/templates/admin_doc /Library/WebServer/mydjangoapp/templates/admin_docln -s /System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/django/contrib/admin/templates/widget /Library/WebServer/mydjangoapp/templates/widgetln -s /System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/django/contrib/admin/templates/registration /Library/WebServer/mydjangoapp/templates/registration

Warning: The following directions will tell you how to get past the db read/access errors but may not be the best choice for security… you consider the possible security issues before following the following instructions.

To get the dispatch.fcgi to work properly, I needed to change ownership of /Library/WebServer/mydjangoapp to be owned by the apache2 user, which is _www on Mac OS X 10.5 and www-data on Debian/Ubuntu systems. The the apache user also needs access to the mydjangoapp.db as well. I ran the following commands on Mac OS X 10.5 when placing the files in /Library/WebServer/gaworkflow:

sudo chown _www:_www /Library/WebServer/mydjangoappsudo chown _www:_www /Library/WebServer/mydjangoapp/mydjangoapp.dbsudo chmod o-rwx /Library/WebServer/mydjangoapp/mydjangoapp.dbsudo chmod ug+rwx /Library/WebServer/mydjangoapp/mydjangoapp.db

new dispatch.fcgi ¶

Replace the hello world dispatch.fcgi with the following script:

#!/usr/bin/python                                                            import syssys.path += ['/Library/WebServer/mydjangoapp']from flup.server.fcgi import WSGIServerfrom django.core.handlers.wsgi import WSGIHandlerimport osos.environ['DJANGO_SETTINGS_MODULE'] = 'mydjangoapp.settings'WSGIServer(WSGIHandler()).run()

You will need to update these two rows:

• sys.path += ['/Library/WebServer/mydjangoapp']
• os.environ['DJANGO_SETTINGS_MODULE'] = ‘mydjangoapp.settings’

Where ‘/Library/WebServer/gaworkflow should be replaced by PYTHONPATH that would allow your Django package to be imported… one directory level below the directory containing init.py.

NOTE: Make sure you dispatch.fcgi is executable:

sudo chmod a+x dispatch.fcgi

If everything worked out properly, you should have a working installation of gaworkflow.frontend using mod_fcgid.

Trouble Shooting

• Check apache error logs.
• run: sudo apachectl configtest
• Check that dispatch.fcgi has #!/usr/bin/python and not #!/usr/bin/env python as that will screw up the environment variables at least w/ Apache 2 that ships on Mac OS 10.5.
• run ‘python dispatch.fcgi’ to see if you get any standard Python errors.

Apache2 – error_log — [warn] mod_fcgid: stderr: OperationalError: unable to open database file

This means the database is not accessible by the user that is running apache. On Mac OS X 10.5, the user is _www. On Debian/Ubuntu Linux the user is www-data. See the “copy of gaworkflow code” section above for directions on changing file permissions for the database.