Nginx conf for an app in different places in different containers

default.conf

server {
    listen       80;

    location / {
        root   /usr/share/nginx/html;
        index  index.php index.html index.htm;
        
        try_files $uri $uri/ /index.php?$query_string;
    }

    # pass the PHP scripts to FastCGI server listening on php:9000
    #
    location ~ \.php$ {
        root          /usr/src/app/public;
        fastcgi_pass   php:9000;
        include        fastcgi_params;
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME $request_filename;
    }
}