nova interface-attach doesn't work if port|network|fixed id is omitted

[shihanzhang]

when use 'interface-attach' to attach interface to a vm with port|network|fixed id is omitted, it will be success if there is one network in that tenant, but it will be failed if there are more than one network in that tenant, also, when nterface-attach faield, there will be residual port in neutron which will not automatically deleted , nova latest code has the same problem!

[Matt Riedemann (mriedem)]

Using neutron or nova-network?

[shihanzhang (shihanzhang)]

neutron

[Weiwen Chen (wei-wen-chen)]

This is a problem:
# nova --insecure interface-attach cirros
ERROR: Failed to attach interface (HTTP 500) (Request-ID: req-0d424f10-0974-41cc-b1a6-9c945f96997c)

https://github.com/openstack/nova/blob/master/nova/compute/manager.py file has the check:
 if len(network_info) != 1:
            LOG.error(_('allocate_port_for_instance returned %(ports)s ports')
                      % dict(ports=len(network_info)))

However, in https://github.com/openstack/nova/blob/master/nova/network/neutronv2/api.py: _get_available_networks()
if no network specified, it will get all networks in the tenant.

If more than one network in the tenant, this will definitely causing the above check failed.

[Racha Ben Ali (racha-ben-ali)]

As part of this patch https://review.openstack.org/#/c/98488/ if more than one network in the tenant and none is requested, then NetworkAmbiguous Exception is raised, without causing the above LOG.error.

[Sean Dague (sdague)]

Assuming this is fixed based on the above patch. If not, please reopen