Passing environment variables from Nginx to PHP-FPM

nginx.conf

server {
    listen 8000;

    server_name mysite.local;
    root /Users/mario/Code/mysite;
   
    location ~ \.php(/|$) {
        include fastcgi_params;
        fastcgi_pass unix:/Users/mario/.phpbrew/php/php-5.6.31/var/run/php-fpm.sock;
        fastcgi_split_path_info ^(.+\.php)(/.*)$;
        fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param  HTTPS off;
        
        # Custom environment variable   
        fastcgi_param DEBUG true;
    }
}