netcfg doesn't work correctly with bond interfaces during ubuntu server installation

[Tina]

When trying to preseed an Ubuntu Server 16.04.4 LTS installation I have run in into a problem:
I have two ethernet interfaces, and configured a bond0 interface with a bond0.1 vlan interface.

But I've noticed when the installer gets to the netcfg part (v1.135ubuntu4.5) it first flushes all network interfaces, than brings all interfaces down, and then brings up only one interface that was chosen from the GUI installation (all four interfaces were available, and I chose bond0.1, it will likely behave the same way when trying to automate it all using a BOOTIF=bond0.1 entry).

Having only one interface up is not very good, since bond0.1 needs bond0 and at least one hw interface up to work properly.

This results in the installer not being able to get the address from DHCP, if I intervene after the error, manually bring up all the interfaces, and then retry network auto-configuration it gets the address from DHCP and I can continue installing as usual.

I believe it would be possible to fix this behaviour if netcfg would check if the chosen interface is a bond* and then it would bring all other bond interfaces and slaves (or at lease all the hw interfaces that have a link) up.

[Tina (leiocalyx)]

There is a patch on debian's bugtracker, but it seems that they haven't implemented it yet.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=611250#39 would be could if you would.