Comment 2 for bug 1760927

Hey Eric, thanks for taking a look at this. Several things:

1. mode is not a dogtag flag, this is an argument in barbican in the create_key method -- https://github.com/openstack/python-barbicanclient/blob/4.6.0/barbicanclient/v1/orders.py#L442-L443
2. castellan is not a service, so can only provide default, which means there will be no way to specify which mode to use. we need to add mode argument here -- https://github.com/openstack/castellan/blob/0.17.0/castellan/key_manager/barbican_key_manager.py#L216-L217, that's why this bug also affects castellan
3. other parameters provided to the key creation method come from VolumeTypeEncryption -- https://github.com/openstack/cinder/blob/a6e79968ed237a7f0982cdc0d8fcf231d63b38fc/cinder/volume/utils.py#L900-L903

Why the mode is required in case of using dogtag backend but is not required when using eg simplecrypt backend might be a bug in barbican, but still would be good to allow providing mode through cinder.