DataSift\Storyplayer\HostLib\VagrantVm::determinePrivateKey PHP Method

    public function determinePrivateKey($vmDetails)
    {
        // what are we doing?
        $log = usingLog()->startAction("determine private key for Vagrant VM '{$vmDetails->hostId}'");
        // the key will be in one of two places, in this order:
        //
        // cwd()/.vagrant/machines/:name/virtualbox/private_key
        // $HOME/.vagrant.d/insecure_private_key
        //
        // we use the first that we can find
        $keyFilenames = [getcwd() . "/.vagrant/machines/{$vmDetails->hostId}/virtualbox/private_key", getenv("HOME") . "/.vagrant.d/insecure_private_key"];
        foreach ($keyFilenames as $keyFilename) {
            usingLog()->writeToLog("checking if {$keyFilename} exists");
            if (file_exists($keyFilename)) {
                $log->endAction($keyFilename);
                return $keyFilename;
            }
        }
        // if we get here, then we do not know where the private key is
        $log->endAction("unable to find Vagrant private key for VM");
        throw new E5xx_ActionFailed(__METHOD__);
    }