Ember CLI: index.php instead of index.html

I'd like to use an index.php file instead of index.html in my ember application.

I found out that I can set the following in my ember-cli-build.js file, which will output my index.html as index.php

outputPaths: {
      app: {
        html: 'index.php'
      }
    }

But with this, the input file still has to be named index.html.

Does anybody know how to configure the app in order to have the source file named index.php, too.