OpenStack-SDK-PHP/MinimumVersion

This document attempts to detail the current state of PHP versions working to find the minimum version of PHP the OpenStack SDK should support. This document is relevant as of February 2014.

PHP Version Usage
According to w3techs, PHP 5 has a 97.7% market share. The minor version usage breakdown as of February 2014 is: Data from w3techs.

Note: For those with Zend Server agreements there will be longer term PHP 5.3 support. Zend have pledged an additional 2 years support for 5.3 after its EOL (March 2013). They will no longer support 5.3 in ~12 months (March 2015).

Edit: According to Zend's current long term support page http://www.zend.com/en/support-center/support/php-long-term-support, Zend Server will have long term support for the versions of PHP in the table below. This support is available for Zend Server Professional/Enterprise edition. Free/Small Business edition do not receive long term support http://www.zend.com/en/support-center/support/production-sla

Ubuntu
Ubuntu release information from wikipedia.

CentOS
You can install PHP 5.5 and 5.4 via yum.

Microsoft

 * The Microsoft Web Platform Installer contains PHP 5.2.17 and 5.3.5. This is for IIS 7 and the latest is IIS 8.5.
 * There are Windows installers with details on what to do for IIS and Apache on the PHP windows download site.
 * The IIS PHP site big install button is for PHP 5.3.
 * Microsoft suggests installing PHP from the Web PI which offers 5.3.
 * WAMP currently offers PHP 5.3 or 5.4.

Wordpress
As of Wordpress 3.2 it requires PHP 5.2.4 or higher.

Joomla
Joomla requires 5.2.4 at the very minimum, but strongly recommends 5.4. The new release will bump this up to 5.3 and there is talk of a 5.4 requirement in the near future.

Yii
Yii2 requires 5.4.

Laravel
Laravel 4.0 and 4.1 currently require PHP 5.3. Taylor Otwell, the lead developer, has announced that Laravel will be moving to 5.4 for the May 2014 release.

Zend Framework
ZF2 requires PHP 5.3.3 or newer. The latest development branch required 5.3.23. There is no ticket to move to a newer version of PHP.

ZF3 is in active development and will require 5.4 at the very minimum.

Apigility
Apigility is Zend's new flagship open-source project for creating APIs with PHP. It requires 5.4.

Symfony
Currently requires PHP 5.3.3 or newer.

Guzzle
Currently 5.3, but will be moving to 5.4 for the next version.

PHPUnit
Requires PHP 5.3.3 or newer.

PHPDoc
Requires PHP 5.3.3 or newer.

AWS SDK
Requires PHP 5.3.3 or newer. With the release of Guzzle 4, I'm fairly sure the AWS SDK will move to 5.4 too.

Azure SDK
Requires PHP 5.3.0 or newer.