openstack通過ceph創建虛擬機報錯，通過查看nova-compute的日誌，發現抱錯如下：
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [req-7b9f4d48-58c4-4f65-b02b-d9a076be81be 7b6e828aeab74727acc303a8f787ef96 6fda007a7dc24d679fff72d1e5ccb287 - default default] [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] Failed to build and run instance: TypeError: Argument must be bytes or unicode, got 'NoneType'
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] Traceback (most recent call last):
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/compute/manager.py", line 2353, in _build_and_run_instance
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] block_device_info=block_device_info)
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 3199, in spawn
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] mdevs=mdevs)
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 5507, in _get_guest_xml
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] xml = conf.to_xml()
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/virt/libvirt/config.py", line 77, in to_xml
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] root = self.format_dom()
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/virt/libvirt/config.py", line 2443, in format_dom
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] self._format_devices(root)
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/virt/libvirt/config.py", line 2401, in _format_devices
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] devices.append(dev.format_dom())
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "/var/lib/kolla/venv/lib/python2.7/site-packages/nova/virt/libvirt/config.py", line 857, in format_dom
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] auth.set("username", self.auth_username)
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "src/lxml/etree.pyx", line 811, in lxml.etree._Element.set
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "src/lxml/apihelpers.pxi", line 569, in lxml.etree._setAttributeValue
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] File "src/lxml/apihelpers.pxi", line 1491, in lxml.etree._utf8
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8] TypeError: Argument must be bytes or unicode, got 'NoneType'
2020-05-24 00:49:16.207 6 ERROR nova.compute.manager [instance: 4359622c-e1ef-486c-9236-d9e4b9b800a8]
這個是因爲缺少配置參數，在libvirt中需要指定rbd_secret_uuid，如下
[libvirt]
......
rbd_secret_uuid = 4aa9152e-a097-4fd8-aba1-29764b3590ff
配置完成後重啓nova-compute服務即可