nginx-default.conf

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    server_tokens off;
    autoindex off;

    root /var/www/html;

    location / {
        index index.php;
    }

    location ~ \.php$ {
        fastcgi_pass roundcubemail-fpm:9000;
        # regex to split $uri to $fastcgi_script_name and $fastcgi_path
        fastcgi_split_path_info ^(.+\.php)(/.+)$;

        # Check that the PHP script exists before passing it
        try_files $fastcgi_script_name =404;

        # Bypass the fact that try_files resets $fastcgi_path_info
        # see: https://trac.nginx.org/nginx/ticket/321
        set $path_info $fastcgi_path_info;
        fastcgi_param PATH_INFO $path_info;

        fastcgi_index index.php;
        include fastcgi.conf;
    }
}