How to log data from a php POST request?

Question

PHP

php-fpm
A simple example.
GET /index.php?some-action
After this request, php will send the data to another server as a POST request.
How to log the request body?
Is it possible to do this without making changes to the php code?

Answer 1

What happens on the server cannot be tracked without access to it.
And if you have access to the server, then you probably have access to the code :)