openstack Horizon Web UI cannot be opened

[xiyao-redhat-com]

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator at [no address given] to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

[zokahn]

long term solution is needed in the automation code for the deployment. However:

Workaround is to log on to the controller host and change permissions on the horizon.log file. It is currently owned by root, hence not writable by apache
ssh into: controller-< YOUR ID >.rhpds.opentlc.com
as root: chown apache:apache /var/log/containers/horizon/horizon.log
(no need to restart any service)