在CentOS 7 上安装OpenStack-dashboard时httpd服务启动失败。
出现如下的报错信息：
controller0 Python[3431]: CommandError: An error occurred during rendering /usr/share/openstack-dashboard/openstack_dashboard/templates/_stylesheets.html: /bin/sh: django_pyscss.compressor.DjangoScssFilter: command not found
controller0 python[3431]: Found 'compress' tags in:
controller0 python[3431]: /usr/lib/python2.7/site-packages/horizon/templates/horizon/_conf.html
controller0 python[3431]: /usr/share/openstack-dashboard/openstack_dashboard/templates/_stylesheets.html
controller0 python[3431]: /usr/lib/python2.7/site-packages/horizon/templates/horizon/_scripts.html
controller0 python[3431]: Compressing...
controller0 systemd[1]: httpd.service: control process exited, code=exited status=1
controller0 systemd[1]: Failed to start The Apache HTTP Server.
centos7 中的python版本为2.7
django-pyscss的版本为要在2.0以上才能正常使用，而自带版本为：
[root@controller0 ~]# yum list|grep django-pyscss
python-django-pyscss.noarch 1.0.5-2.el7 @epel
所以需要更新django-pyscss版本，过程如下：
1、首先安装 pip
参照：
2、安装新版本django-pyscss
[root@controller0 tmp]#pip install django-pyscss==2.0.2
[root@controller0 tmp]# pip list | grep pyscss
django-pyscss (2.0.2)
重新启动httpd：
systemctl start httpd.service