MAAS bridge script doesn't bridge aliases correctly where --interface-to-bridge is specified

[Andrew McDermott]

If you have the following:

auto eth0
iface eth0 inet static
    address 172.16.0.129/24
    mtu 1500

auto eth0:1
iface eth0:1 inet static
    address 172.16.0.130/24
    mtu 1500

and (using 1.25) we bridge as:

  $ add-juju-bridge.py --interface-to-bridge=eth0 --bridge-name=juju-br0 ~/foo.eni

then the output becomes:

auto eth0
iface eth0 inet manual
    mtu 1500

auto juju-br0
iface juju-br0 inet static
    address 172.16.0.129/24
    bridge_ports eth0

auto eth0:1
iface eth0:1 inet static
    address 172.16.0.130/24
    mtu 1500

eth0:1 should really become juju-br0-eth0:1.

This is only a problem on Juju 1.25 because we only bridge specific interfaces; on Juju 2.0 we bridge all (appropriate) interfaces.

[Dimiter Naydenov (dimitern)]

I'm not sure this is an actual issue that needs fixing. Adding an alias to a NIC with an address from a different subnet for example, will allow access both via juju-br0 (with its primary address, migrated from the NIC on the default route, e.g. eth0), and via the alias on the underlying (not bridged as port) eth0. Numerous sources I've read all seem to point to "aliases are ifconfig-specific syntax sugar, not separate interfaces", so I'd vote to keep the current 1.25 bridge script logic as-is.