计算节点openstack-nova-compute起不来，求大神指点

[root@compute ~]# 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.
[root@compute ~]#
[root@compute ~]#
[root@compute ~]# journalctl -xe
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit openstack-nova-compute.service has failed.
--
-- The result is failed.
1月 02 16:42:32 compute systemd[1]: Unit openstack-nova-compute.service entered failed state.
1月 02 16:42:32 compute systemd[1]: openstack-nova-compute.service failed.
1月 02 16:42:32 compute systemd[1]: openstack-nova-compute.service holdoff time over, scheduling restart.
1月 02 16:42:32 compute systemd[1]: Starting OpenStack Nova Compute Server...
-- Subject: Unit openstack-nova-compute.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit openstack-nova-compute.service has begun starting up.
1月 02 16:42:33 compute python[10294]: detected unhandled Python exception in '/usr/bin/nova-compute'
1月 02 16:42:33 compute abrt-server[10301]: Not saving repeating crash in '/usr/bin/nova-compute'
1月 02 16:42:33 compute nova-compute[10294]: Traceback (most recent call last):
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/bin/nova-compute", line 10, in <module>
1月 02 16:42:33 compute nova-compute[10294]: sys.exit(main())
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/lib/python2.7/site-packages/nova/cmd/compute.py", line 59, in main
1月 02 16:42:33 compute nova-compute[10294]: logging.setup(CONF, 'nova')
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/lib/python2.7/site-packages/oslo_log/log.py", line 211, in setup
1月 02 16:42:33 compute nova-compute[10294]: _setup_logging_from_conf(conf, product_name, version)
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/lib/python2.7/site-packages/oslo_log/log.py", line 263, in _setup_logging_from_conf
1月 02 16:42:33 compute nova-compute[10294]: filelog = logging.handlers.WatchedFileHandler(logpath)
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/lib64/python2.7/logging/handlers.py", line 392, in __init__
1月 02 16:42:33 compute nova-compute[10294]: logging.FileHandler.__init__(self, filename, mode, encoding, delay)
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/lib64/python2.7/logging/__init__.py", line 902, in __init__
1月 02 16:42:33 compute nova-compute[10294]: StreamHandler.__init__(self, self._open())
1月 02 16:42:33 compute nova-compute[10294]: File "/usr/lib64/python2.7/logging/__init__.py", line 925, in _open
1月 02 16:42:33 compute nova-compute[10294]: stream = open(self.baseFilename, self.mode)
1月 02 16:42:33 compute nova-compute[10294]: IOError: [Errno 13] Permission denied: '/var/log/nova/nova-compute.log'
1月 02 16:42:33 compute systemd[1]: openstack-nova-compute.service: main process exited, code=exited, status=1/FAILURE
1月 02 16:42:33 compute systemd[1]: Failed to start OpenStack Nova Compute Server.
-- 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.
1月 02 16:42:33 compute systemd[1]: Unit openstack-nova-compute.service entered failed state.
1月 02 16:42:33 compute systemd[1]: openstack-nova-compute.service failed.
1月 02 16:42:33 compute systemd[1]: openstack-nova-compute.service holdoff time over, scheduling restart.
1月 02 16:42:33 compute systemd[1]: start request repeated too quickly for openstack-nova-compute.service
1月 02 16:42:33 compute systemd[1]: Failed to start OpenStack Nova Compute Server.
-- 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.
1月 02 16:42:33 compute systemd[1]: Unit openstack-nova-compute.service entered failed state.
1月 02 16:42:33 compute systemd[1]: openstack-nova-compute.service failed.

chown -R nova:nova /var/log/nova/nova-compute.log
这种原因是由于文件权限改变了，导致nova-compute没有权限读取文件，从而起不来

错误的原因比较多：
1.nova.conf可能错误，特别是 [DEFAULT] 部分
2.环境变量没有生效
3.rabbitmq通信失败，查看是否有问题