[stack@instack ~]$ sudo nova-manage --config-file /etc/nova/nova.conf cell_v2 simple_cell_setup usage: nova-manage cell_v2 simple_cell_setup [-h] --transport-url <transport url> nova-manage cell_v2 simple_cell_setup: error: argument --transport-url is required
So it seems you're forced to provide the --transport-url even when you point to the nova.conf :(
[stack@instack ~]$ sudo nova-manage --config-file /etc/nova/nova.conf cell_v2 simple_cell_setup
url>
usage: nova-manage cell_v2 simple_cell_setup [-h] --transport-url <transport
nova-manage cell_v2 simple_cell_setup: error: argument --transport-url is required
So it seems you're forced to provide the --transport-url even when you point to the nova.conf :(