You can include a php.ini file with your App Engine application. This
file lets you customize the behavior of the PHP interpreter directives.
See an example of the default php.ini configuration.
Using a custom php.ini file
Place the php.ini file in your application's base directory where your
app.yaml file is located. It is loaded when the PHP interpreter is
initialized, before running your application code.
The file follows the same syntax as other .ini files.
A simple example might look like:
; This is a simple php.ini file on App Engine
; It enables output buffering for all requests by overriding the
; default setting of the PHP interpreter.
output_buffering = "On"
A list of the core directives, along with their changeable mode values, is published on php.net.
You can override any PHP directive that has one of the following changeable mode values:
PHP_INI_SYSTEMPHP_INI_ALLPHP_INI_PERDIR
You can enable a set of dynamically loadable extensions
by using the extension directive.