Running mod_php and FastCGI side-by-side

Because we're in full throes of Zend Framework 2.0 development, I find myself with a variety of PHP binaries floating around my system from both the PHP 5.2 and 5.3 release series. We're at a point now where I'm wanting to test migrating applications from ZF 1.X to 2.0 to se see what works and what doesn't. But that means I need more than one PHP binary enabled on my server…

I use Zend Server on my development box; it's easy to install, and uses my native Ubuntu update manager to get updates. On Ubuntu, it installs the Debian Apache2 packages, so I get the added bonus of familiarity with the configuration structure.

I installed Zend Server some time ago, so I'm still on a PHP 5.2 mod_php binary. I have several PHP 5.3 binaries compiled and installed locally for running unit tests and sample scripts already — so the question was how to keep my 5.2 mod_php running while simultaneously allowing the ability to run selected vhosts in 5.3?

The answer can be summed up in one acronym: FastCGI.

With a little help from Ralph Schindler, I got things setup.

Enabling FastCGI on Ubuntu's Apache

Interestingly, FastCGI is not enabled by default, nor is another module you'll need, mod_actions. You can enable these very easily though:

$ cd /etc/apache2/mods-enabled
$ sudo ln -s ../mods-available/fastcgi.load .
$ sudo ln -s ../mods-available/fastcgi.conf .
$ sudo ln -s ../mods-available/actions.load .
$ sudo ln -s ../mods-available/actions.conf .

Create a FastCGI-enabled vhost

Next, you need to add a new vhost that will utilize FastCGI. I copied an existing vhost I had in my /etc/apache2/sites-enabled tree, modified it to give it a unique ServerName and DocumentRoot, and added the following lines:

ScriptAlias /cgi-bin/ /path/to/zfproject/public/cgi-bin/
AddHandler php-fcgi .php
Action php-fcgi /cgi-bin/php-5.3.1

The name of the PHP script doesn't matter much; I used "php-5.3.1" so that I could visually recognize what version of PHP I was using with that vhost.

Create a "cgi-bin" directory and CGI script

Finally, I needed to actually create the "cgi-bin" directory and CGI script to execute. This was relatively simple; I navigated to my project's DocumentRoot, and created a new directory cgi-bin (mkdir cgi-bin).

I then entered that directory and created a new script, based on the name I provided in my vhost. That script, cgi-bin/php-5.3.1 then simply exec's the php-cgi binary from my PHP install.

Note about CGI binaries

In PHP 5.3 and up, CGI binaries are built by default — and they're already FastCGI enabled. In PHP 5.2, CGI versions are still built by default, but they are not FastCGI-enabled unless you explicitly pass the --enable-fastcgi configure flag. To determine if you did that when compiling, execute the following:

$ php-cgi -i | grep fcgi

If you get no output, you need to recompile.

My script looks like this:

exec /path/to/php/install/bin/php-cgi "$@"

Because this is a CGI binary, you can pass additional CLI arguments and environment variables; try experimenting with setting your include_path, application environment, etc.

Once you're done creating the script, make sure it's executable:

$ chmod a+x php-5.3.1

Fire it up!

Once I'd done the above, I restarted my Apache instance (sudo /etc/init.d/apache2 restart). After ensuring there were no startup errors, I navigated to my new vhost, and voila! it was running.

For those of you doing your first forays into PHP 5.3, this is an excellent way to test code without needing a separate server running. It's also a great way to test whether your application is 5.3-ready — create a 5.3-enabled vhost pointing to your existing application and see if it runs.