Nginx php in subdirectory

Wordpress is in sub-directory nested, and blog address is domain.tld/nested

useful links
https://serversforhackers.com/c/nginx-php-in-subdirectory
https://www.nginx.com/resources/wiki/start/topics/tutorials/config_pitfalls/

server {

  listen 80 default_server; 

  listen [::]:80 default_server; 

  root /var/www/top/public; 

  index index.html index.htm index.php; 

  server_name _; 

  location / { 

    try_files $uri $uri/ /index.php$is_args$args; 

  } 

  location /nested { 

    alias /var/www/nested/public; 

    try_files $uri $uri/ @nested; 

    location ~ \.php$ { 

      index index.php;

      include snippets/fastcgi-php.conf; 

      fastcgi_param SCRIPT_FILENAME $request_filename; 

      fastcgi_pass unix:/var/run/php/php7.2-fpm.sock; 

    } 

  } 

  location @nested { 

    rewrite /nested/(.*)$ /nested/index.php?/$1 last; 

  } 

  location ~ \.php$ { 

    include snippets/fastcgi-php.conf; 

    fastcgi_pass unix:/var/run/php/php7.2-fpm.sock; 

  }

}

Short explanations.

1) root of blog is not domain as domain.tld, but it is address location as domain.tld/nested. So there should be rewrite rule:

    rewrite /nested/(.*)$ /nested/index.php?/$1 last;

2) We use alias, because of explanation from one of useful links below.

Note that distinction - with that alias, Nginx does NOT look for files within /var/www/nested/public/nested/foo, like it would with the root directive.

3) We use $request_filename instead of $document_root$fastcgi_script_name because of next explanation.
If you use the alias directive with $document_root$fastcgi_script_name, $document_root$fastcgi_script_name will return the wrong path.

Request /api/testing.php:

• $document_root$fastcgi_script_name == /app/www//api/testing.php
• $request_filename == /app/www/testing.php

Request /api/:

• $document_root$fastcgi_script_name == /app/www//api/index.php
• $request_filename == /app/www/index.php

4) And if you use $request_filename, you should set index using index directive, fastcgi_index will not work.

It means index index.php; in location