unmatch attribute while calling get_grant_resource

[LiangLu]

while calling get_grant_resource() from _scale_grant in conductor,
an unmatch parameter happened:

2021-04-15 17:14:05.531 TRACE oslo_messaging.rpc.server ^[[01;35m^[[00mTypeError: get_grant_resource() got an unexpected keyword argument 'plugin'

This error is caused by calling get_grant_resource() with parameter 'plugin'

https://opendev.org/openstack/tacker/src/branch/master/tacker/conductor/conductor_server.py#L1202

however in openstack.py, get_grant_resource() does not have this parameter:

https://opendev.org/openstack/tacker/src/branch/master/tacker/vnfm/infra_drivers/openstack/openstack.py#L1803

Solution: add 'plugin=None' to get_grant_resource()

[Yasufumi Ogawa (yasufum)]

Hi,

Looking at openstack infra_driver quickly, there is some common style to have an arg `plugin` and caller gives `self` to it even if it's not used actually. So, why don't you follow the convention at once instead of using default value `None` exceptionally?

[Hiromu Asahina (h-asahina)]

Thank you for your suggestion.
As you pointed out, there is some common style we can follow.

There are two reasons I decided to delete this arg instead of following such style:
i) It's not used (as you pointed out);
ii) The infra drivers inherit an abstract class `VnfScaleAbstractDriver` that defines `get_grant_resource` method without `plugin` arg.

I guess, in general, abstract classes shouldn't be changed frequently.
Would you give me your thoughts?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/tacker/+/795016

[Yi Feng (fengyi765)]

To Hiromu Asahina:
Sorry, I don't know this bug has assigned to you.
In my branch https://review.opendev.org/c/openstack/tacker/+/795016, I have fixed this bug just delete the `plugin` arg in `conductor_server` to make my modification for get_grant_resource_scale_out can work correctly.
If you have other solutions, I can withdraw the modification or you can comment on my patch and let me modify it.

[Hiromu Asahina (h-asahina)]

Thank you for letting me know.
I commented on your patch.