That's coercing the value None to a string 'None' so it fails. According to Ben Nemec:
(02:13:48 PM) bnemec: The only way for a config opt to have a None value is for that to be the default and for the opt to be unset.
(02:14:14 PM) bnemec: So completely absent from the file, not something like "opt="
But that seems like a bug because I would think that code could be smarter about not coercing the value if the value is None, None is a valid choice and a default is set (so you need to override the default).
The problem is in oslo.config I think right here:
https:/ /github. com/openstack/ oslo.config/ blob/20a7cee3e3 019d60c4b367bb7 6922a1db41d1750 /oslo_config/ types.py# L142
That's coercing the value None to a string 'None' so it fails. According to Ben Nemec:
(02:13:48 PM) bnemec: The only way for a config opt to have a None value is for that to be the default and for the opt to be unset.
(02:14:14 PM) bnemec: So completely absent from the file, not something like "opt="
But that seems like a bug because I would think that code could be smarter about not coercing the value if the value is None, None is a valid choice and a default is set (so you need to override the default).