src/Kernel.php
public function getAppPath(): string
    {
        if ($this->appPath == '') {
            $r = new \ReflectionObject($this);
            $this->setAppPath(str_replace('\\', '/', dirname($r->getFileName())));
        }

        return $this->appPath;
    }
public function getAppPath(): string
    {
        if ($this->appPath == '') {
            $r = new \ReflectionObject($this);
            $this->setAppPath(str_replace('\\', '/', dirname($r->getFileName())));
        }

        return $this->appPath;
    }
Returns app path, e.g. /var/www/app

@return string