Specify the PHP version
By default the PHP Runtime buildpack uses the latest stable version of PHP. If
your application requires a specific version, you can specify one by including
a composer.json 
file in your application's root directory. For example:
  "require" 
 : 
  
 { 
  
 "php" 
 : 
  
 "8.3.*" 
 , 
 } 
 
 
Configure Composer
By default, the Composer version is 2.1.3 
. If you require a specific
version of Composer, you can use the GOOGLE_COMPOSER_VERSION 
environment
variable to specify any supported version of Composer using the full
semantic version. For example:
  pack build sample-php --builder=gcr.io/buildpacks/builder \ 
 --env GOOGLE_COMPOSER_VERSION="2.2.20" 
 
 
Customizing NGINX configurations
To configure NGINX, you can use the GOOGLE_CUSTOM_NGINX_CONFIG 
environment
variable to specify your custom NGINX configuration file. For example:
  pack build sample-php --builder=gcr.io/buildpacks/builder \ 
 --env GOOGLE_CUSTOM_NGINX_CONFIG="nginx-custom.conf" 
 
 
When NGINX starts, your custom NGINX file is used.

