“An error occurred authenticating. Please try again later”。
然後在這個網站找到了答案：http://fosshelp.blogspot.com/2013/01/how-to-fix-openstack-login-error-error.html
還有視頻。。需要翻牆去看：
* Horizon use keystone to authenticate.
* devstack run all the service in a screen session.
* When you reboot, this screen session is stopped and all the services with it.
* Running "rejoin-stack.sh" relaunch the screen session and the associated
* services (notably keystone).
* Without this script, no keystone => no auth.
* So run the script ./rejoin-stack.sh and login in horizon after.‘
* devstack run all the service in a screen session.
* When you reboot, this screen session is stopped and all the services with it.
* Running "rejoin-stack.sh" relaunch the screen session and the associated
* services (notably keystone).
* Without this script, no keystone => no auth.
* So run the script ./rejoin-stack.sh and login in horizon after.‘
簡單說就是重啓後screen session沒有啓動並且和keystone進行關聯，要運行一下rejoin-stack.sh，在~/devstack目錄下。
2，上次做syslog-ng的實驗，suse環境，更改幾次配置重啓服務後會收到重複的日誌，而且後來同一日誌會出現三四次。
用ps -aux 查看進程，發現有很多syslog-ng的restart進程，kill掉就好了。
當初沒有深入探究。。留待以後遇到類似問題了在歸檔吧