Comment 2 for bug 1675489

I think this is reasonable request. As a user, when debugging something, I usually type both commands "openstack router show" and "openstack port list --router" to know the detail of a specific router, so it would be nice if a list of interfaces is included in the output of 'openstack router show'.

I think necessary information on router interface (port) are: IP address, subnet ID (and port ID).
IP address is usually needed to ping to the router.
Subnet ID (or port ID) is required when we want to run "openstack port remove".
If the output is like "IP address: xxxx, subnet ID: xxxxx, port ID: xxxxx", users can know more detail of the port by "openstack port show".

The output format is one concern when we implement this.
Something like JSON blob might help us.
Another idea is to wrap lines with shorter width.
 | interfaces | - 10.1.1.1
 | | Port ID 7e72f486-784c-4c17-996b-e932ae9bc29c
 | | Subnet ID fdd13fb1-f264-4cf4-ba13-18e52ee44691
 | | - 192.168.20.254
 | | Port ID e4f1f43e-f1d6-4d5e-b2e3-144d464b9cdb
 | | Subnet ID 48ac1947-0299-4106-b8b8-634718e62567

To show this information, we need one extra call, but one extra would be okay as we do more calls for "show" commands.

Note that we already have a equivalent command of "neutron router-port-list". It is "openstack port list --router <router>".
Currently we don't have any "router" related keyword in the help message, so it is sometimes difficult to find the command.