Hi,

I'm starting to install OpenStack on a controller and compute node (both running CentOS 7) with the official installation guide. I've just changed the hostname of my controller server from "localhost.localdomain" to "controller"; I had forgotten to do so earlier. Everything has just broken. When I run the command openstack compute service list, all the services are "down."

+----+------------------+------------+----------+---------+-------+----------------------------+
| ID | Binary           | Host       | Zone     | Status  | State | Updated At                 |
+----+------------------+------------+----------+---------+-------+----------------------------+
| 11 | nova-compute     | compute1   | nova     | enabled | down  | 2017-07-06T15:52:01.000000 |
| 12 | nova-consoleauth | controller | internal | enabled | down  | None                       |
| 13 | nova-conductor   | controller | internal | enabled | down  | None                       |
| 14 | nova-scheduler   | controller | internal | enabled | down  | None                       |
+----+------------------+------------+----------+---------+-------+----------------------------+

The error messages on the controller are all very similar.

tail -n 50 /var/log/nova/nova-scheduler.log

…

2017-07-06 10:29:14.306 28323 ERROR oslo_service.service   File "/usr/lib/python2.7/site-packages/amqp/connection.py", line 273, in _wait_method
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service     self.wait()
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service   File "/usr/lib/python2.7/site-packages/amqp/abstract_channel.py", line 69, in wait
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service     return self.dispatch_method(method_sig, args, content)
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service   File "/usr/lib/python2.7/site-packages/amqp/abstract_channel.py", line 87, in dispatch_method
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service     return amqp_method(self, args)
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service   File "/usr/lib/python2.7/site-packages/amqp/connection.py", line 529, in _close
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service     (class_id, method_id), ConnectionError)
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service AccessRefused: (0, 0): (403) ACCESS_REFUSED - Login was refused using authentication mechanism AMQPLAIN. For details see the broker logfile.
2017-07-06 10:29:14.306 28323 ERROR oslo_service.service

The compute node cannot start the service openstack-nova-compute.service. This was working properly before the controller hostname was changed and was "up" on openstack compute service list.

systemctl start openstack-nova-compute.service
Job for openstack-nova-compute.service failed because the control process exited with error code. See "systemctl status openstack-nova-compute.service" and "journalctl -xe" for details.

The commands it recommends are not too helpful.

journalctl -xe
-- Unit openstack-nova-compute.service has begun starting up.
Jul 06 10:35:38 compute1 systemd[1]: openstack-nova-compute.service: main proces
Jul 06 10:35:38 compute1 systemd[1]: Failed to start OpenStack Nova Compute Serv
-- Subject: Unit openstack-nova-compute.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit openstack-nova-compute.service has failed.
-- 
-- The result is failed.

The error messages are generic.

systemctl status openstack-nova-compute.service
● openstack-nova-compute.service - OpenStack Nova Compute Server
   Loaded: loaded (/usr/lib/systemd/system/openstack-nova-compute.service; enabled; vendor preset: disabled)
   Active: activating (start) since Thu 2017-07-06 10:39:25 MDT; 767ms ago
 Main PID: 8461 (nova-compute)
   CGroup: /system.slice/openstack-nova-compute.service
           └─8461 /usr/bin/python2 /usr/bin/nova-compute

Jul 06 10:39:25 compute1 systemd[1]: Starting OpenStack Nova Compute Server...

The services stay in the "starting" state, which leads me to believe they are not ... (more)