Below is the announcement.
In response to developer feedback, we have introduced a significant upgrade of PHP in the latest release of App Engine with more features and improved performance.
The updates include:
Support for the PHP 5.5 runtime, alongside the current PHP 5.4 runtime.
The cURL extension is now available, meaning curl_*() functions can now be used from within your application (read more about how to enable cURL support in our documentation).
The tempnam() and sys_get_temp_dir() functions are now available.
Support for direct file uploads.
Support for concurrent requests, which allows the PHP interpreter to run an efficient multi-threaded mode when serving HTTP requests. This must be enabled in your app.yaml file.
Support for the ImageMagick extension (which allows powerful image manipulation) and MongoDB extension (which allows you to connect to an existing MongoDB installation).
While we expect most users will enjoy the benefits of this upgrade without any problems, in some cases it may cause unexpected behavior in running applications. We are providing an 8 week window (starting today) for developers to self-upgrade and test their applications with this new functionality before we upgrade all applications automatically, starting after 16th April, 2015.
To take advantage of these new features, find your ‘app.yaml’ file and change the line that reads
The new functionality will automatically be enabled in the local development server, and in production once your application is deployed. You will be able to switch back to the old runtime at any time for the next two months by reverting the configuration in your app.yaml file. Some features such as cURL support may require additional configuration in order to be enabled.
After 16th April, 2015 we will begin automatically migrating all applications to the php55 runtime.
If you are experiencing difficulties in migrating your application, you can find help on the Google App Engine Stack Overflow Tag, or if you have a support package you may open a support ticket. If you’ve found an an issue with App Engine itself you may also file a bug on our public issue tracker.
We hope you enjoy these latest improvements to PHP on App Engine. Keep on coding!
– The PHP for App Engine Team