{
    grace_period 3s
    frankenphp {
        num_threads 32
        max_threads 128
        worker {
            file /var/www/app/public/index.php
            num 16
            env APP_ENV one
        }
        worker {
            file /var/www/app/public/index.php
            num 16
            env APP_ENV two
        }
    }
}

one.example.com {
    root * /var/www/app/public/
    ...
    php_server {
        env APP_ENV one
    }
}

two.example.com {
    root * /var/www/app/public/
    ...
    php_server {
        env APP_ENV two
    }
}