For PHP enabled through App Settings, we cannot modify php.ini directly. However, we can modify it by using XDT transformation:
Copy php.ini for the version you are using to D:\home\site
For ex, when using php 5.6:
Copy d:\local\Config\PHP-5.6.10\php.ini d:\home\site\php56.ini
After this add applicationHost.xdt file in D:\home\site folder and add php.ini file.
For ex. For php 5.6, below is the applicationHost.xdt file:
<?xml version=”1.0″?>
<configuration xmlns:xdt=”http://schemas.microsoft.com/XML-Document-Transform”>
<system.webServer>
<fastCgi>
<application fullPath=”D:\Program Files (x86)\PHP\v5.6\php-cgi.exe” xdt:Locator=”Match(fullPath)”>
<environmentVariables>
<environmentVariable name=”PHPRC” xdt:Locator=”Match(name)” value=”d:\home\site\php56.ini” xdt:Transform=”SetAttributes(value)”
/>
</environmentVariables>
</application>
</fastCgi>
</system.webServer>
</configuration>
You can then make changes to your php.ini file and those should take effect.