访问controller/horizon出错500：internal server error
访问controller/horizon出错504：internal server error gateway timeout
解决方案：
WSGIApplicationGroup %{GLOBAL}
把上面这行添加到/etc/apache2/conf-available/openstack-dashboard.conf
openstack安装dashboard后访问horizon出错 500 or 504
原文：http://www.cnblogs.com/amwuau/p/6518279.html