Comment 1 for bug 1872399

Main error snippet:-

https://logserver.rdoproject.org/openstack-component-compute/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-standalone-full-tempest-scenario-compute-master/b952891/logs/undercloud/var/log/containers/httpd/nova-api/nova_api_wsgi_error.log.txt.gz

~~~
[Sun Apr 12 09:35:27.215667 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] mod_wsgi (pid=25): Failed to exec Python script file '/var/www/cgi-bin/nova/nova-api'.
[Sun Apr 12 09:35:27.215757 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] mod_wsgi (pid=25): Exception occurred processing WSGI script '/var/www/cgi-bin/nova/nova-api'.
[Sun Apr 12 09:35:27.216907 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] Traceback (most recent call last):
[Sun Apr 12 09:35:27.216963 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] File "/var/www/cgi-bin/nova/nova-api", line 6, in <module>
[Sun Apr 12 09:35:27.216970 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] from nova.api.openstack.compute.wsgi import init_application
[Sun Apr 12 09:35:27.216978 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] File "/usr/lib/python3.6/site-packages/nova/api/openstack/compute/__init__.py", line 21, in <module>
[Sun Apr 12 09:35:27.216982 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] from nova.api.openstack.compute.routes import APIRouterV21 # noqa
[Sun Apr 12 09:35:27.216988 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] File "/usr/lib/python3.6/site-packages/nova/api/openstack/compute/routes.py", line 43, in <module>
[Sun Apr 12 09:35:27.216992 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] from nova.api.openstack.compute import flavors_extraspecs
[Sun Apr 12 09:35:27.216998 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] File "/usr/lib/python3.6/site-packages/nova/api/openstack/compute/flavors_extraspecs.py", line 24, in <module>
[Sun Apr 12 09:35:27.217002 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] from nova.api.validation.extra_specs import validators
[Sun Apr 12 09:35:27.217008 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] File "/usr/lib/python3.6/site-packages/nova/api/validation/extra_specs/validators.py", line 23, in <module>
[Sun Apr 12 09:35:27.217012 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] from nova.api.validation.extra_specs import base
[Sun Apr 12 09:35:27.217018 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] File "/usr/lib/python3.6/site-packages/nova/api/validation/extra_specs/base.py", line 15, in <module>
[Sun Apr 12 09:35:27.217022 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] import dataclasses
[Sun Apr 12 09:35:27.217038 2020] [wsgi:error] [pid 25] [remote 192.168.24.1:41778] ModuleNotFoundError: No module named 'dataclasses'
~~~