Change the script path in an Apache proxy handler

I'm developing my application with 2 containers: apache and php-fpm.

Apache serves requests, and delegates PHP execution to the php-fpm container in its vhost:

 <FilesMatch .php$> SetHandler "proxy:fcgi://myapp-php-fpm:9000" </FilesMatch> 

The two containers share a single volume that contains the application code.

The location of that volume is different in each of the containers:

• apache mounts the app code volume at /home/wwwdata/myapp
• php-fpm mounts the app code volume at /var/task

How can I change the script path that Apache sends to the php-fpm container, so that it matches where the volume is mounted in the php-fpm container?

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I can do this in nginx by setting SCRIPT_FILENAME and DOCUMENT_ROOT:

 location ~ ^/index\.php(/|$) { fastcgi_pass myapp-php-fpm:9000; fastcgi_split_path_info ^(.+\.php)(/.*)$; include fastcgi_params; fastcgi_param SCRIPT_FILENAME /var/task/$fastcgi_script_name; fastcgi_param DOCUMENT_ROOT /var/task; internal; } 

but I haven't been able to replicate this behavior in Apache.