新增 Instance ERROR 2

1. 新增 instance 時，狀態 ERROR，查詢 log，只有 manager.py, config.py, ...等 python 程式回應錯誤。

   [root@ip110 ~]<demo># grep -m1 ERROR.*site /var/log/nova/nova-compute.log
   2020-05-26 08:00:31.520 141464 ERROR nova.compute.manager [instance: 
   dce5c044-ebb5-465b-8225-0ad48861902c]   File "/usr/lib/python2.7/site-packages/
   nova/compute/manager.py", line 2239, in _build_resources
   

2. log 查無其他問題，但就是 openstack server create 新增 instance，狀態一直是 ERROR。問題為 /usr/lib/python2.7/site-packages/nova/virt/libvirt 目錄中的 driver.py 及 config.py 修改過，將 nova 相關的套件䧏版或重安裝，成功新增 instance。

   [root@ip110 ~]<demo># yum downgrade python-nova openstack-nova-*
   
   [root@ip110 ~]<demo># rpm -qa | grep nova
   python-nova-17.0.6-1.el7.noarch
   openstack-nova-placement-api-17.0.6-1.el7.noarch
   openstack-nova-scheduler-17.0.6-1.el7.noarch
   openstack-nova-console-17.0.6-1.el7.noarch
   openstack-nova-spicehtml5proxy-17.0.6-1.el7.noarch
   python2-novaclient-10.1.0-1.el7.noarch
   openstack-nova-compute-17.0.6-1.el7.noarch
   openstack-nova-novncproxy-17.0.6-1.el7.noarch
   openstack-nova-api-17.0.6-1.el7.noarch
   openstack-nova-common-17.0.6-1.el7.noarch
   openstack-nova-conductor-17.0.6-1.el7.noarch