[5.7] Remove fastcgi_split_path_info from nginx config

[0xb4lint]

Hello @taylorotwell!

You've probably missed my previous PR's (#4847) comments, let me summarize to create a whole picture.

fastcgi_split_path_info

What is purpose of the fastcgi_split_path_info nginx directive?

It constructs the $fastcgi_path_info variable from the given regex (with exactly 2 capture groups).
Most widely used value is ^(.+\.php)(/.+)$. (nginx docs)

What is effect of using fastcgi_split_path_info?

The $fastcgi_path_info value will be set to the processed path's portion after the .php extension.
Example: https://laravel.com/test.php/foo/bar => /foor/bar.

How can I use the $fastcgi_path_info variable?

Now we may have some value assigned to $fastcgi_path_info, but we have to pass it to PHP via the PATH_INFO variable (the default /etc/nginx/fastcgi_params file does not handle it).
The standard way to do that: fastcgi_param PATH_INFO $fastcgi_path_info.

What is prerequisite of using fastcgi_split_path_info?

Since the only use-case is getting the substring (routing) after the .php file, we have to create a location block which handles such paths.
Most widely used location block to do that:

location ~ [^/]\.php(/|$) {
    ...
}

Should I use the fastcgi_split_path_info?

Only if you have to deal with /index.php/foo/bar style routes (or slash arguments as Moodle calls it).
Typical applications which require it: Moodle, older Joomla!, Drupal (only update route), Magento (only update route) or any legacy stuff.
Some applications which support it: Symfony (note the internal directive), Slim (note the missing $)
Some applications which don't support it: Yii 2, Zend, CodeIgniter, CakePHP, WordPress

Can I see some example?

Example reques #1: https://laravel.com/test.php

• without fastcgi_split_path_info:
  • $fastcgi_script_name: /test.php
  • $fastcgi_path_info: no value
• with fastcgi_split_path_info (value: ^(.+\.php)(/.+)$):
  • $fastcgi_script_name: /test.php
  • $fastcgi_path_info: no value

Example request #2: https://laravel.com/test.php/foo/bar

• without fastcgi_split_path_info:
  • $fastcgi_script_name: /test.php/foo/bar
  • $fastcgi_path_info: no value
• with fastcgi_split_path_info (value: ^(.+\.php)(/.+)$):
  • $fastcgi_script_name: /test.php
  • $fastcgi_path_info: /foo/bar

fastcgi_split_path_info × Laravel

What's the issue with nginx configuration?

The Deployment documentation of Laravel suggests the following nginx PHP location block:

location ~ \.php$ {
    fastcgi_split_path_info ^(.+\.php)(/.+)$;
    fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}

Issues:

1. The location regex restricts the processed path to end with .php (e.g. /test.php), so it won't process a route with slash arguments (e.g. /test.php/foo/bar).
2. If only the .php$ paths will be processed the there is no point of using fastcgi_split_path_info.
3. Even if we are using the fastcgi_split_path_info directive, the generated $fastcgi_path_info (without value in this case) isn't used anywhere.

Solutions

#1 Get rid of fastcgi_split_path_info

The most obvious way to handle this anomaly is removing the fastcgi_split_path_info directive, as I suggested in this PR.
The final location block would be:

location ~ \.php$ {
    fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}

#2 Allow slash arguments

Another way to make the configuration useful is extending the location regex to: [^/]\.php(/|$)
The final location block would be:

location ~ [^/]\.php(/|$) {
    fastcgi_split_path_info ^(.+\.php)(/.+)$;
    fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}

(#3 Hybrid solution)

Laravel's Illuminate\Http\Request class extends Symfony\Component\HttpFoundation\Request class, which handles the PATH_INFO variable if present, but also can construct it from the url. We can get rid of fastcgi_split_path_info directive (since we currently do not pass the PATH_INFO variable to PHP) and allow the slash arguments processing location regex.

location ~ [^/]\.php(/|$) {
    fastcgi_pass unix:/var/run/php/php7.2-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}

Thanks for reading this.
What do you think @taylorotwell?

P.S. Sorry for the duplicate PR.