Comment 61 for bug 1573272

Testing on artful:

I created a virtual guest with extra interfaces to use for testing, all connected to a single host bridge, which are named ens7-12 in the guest. I added e/n/i configuration to test both for the original problem for this bug (vlan on bond loses gateway) as well as the bug introduced by the first patch (vlan without raw device ifupdown config fails), with this configuration:

auto ens7.100
iface ens7.100 inet static
 address 1.2.3.5/24
 gateway 1.2.3.1
 metric 1000
 vlan-raw-device ens7

auto ens8
iface ens8 inet manual
 bond-master bond0

auto ens9
iface ens9 inet manual
 bond-master bond0

auto bond0
iface bond0 inet static
 address 4.5.6.8/24
 gateway 4.5.6.1
 metric 2000
 bond-slaves none
 bond-mode balance-alb

auto bond0.200
iface bond0.200 inet static
 address 9.8.7.7/24
 gateway 9.8.7.1
 metric 3000
 vlan-raw-device bond0

Notes:
'ens7.100' does not have any corresponding 'ens7' configuration.
'bond0' requires the 'bond-mode' option to trigger this bug, as it takes down the interface while changing the mode; the other options that take down the interface are 'xmit_hash_policy', 'ad_select', and 'lacp_rate'.

Without the modification from comment 8, I could not reproduce the bug (as expected since it's a race condition), but with that modification I could reproduce the bug with vlan version:

$ dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu2

The bond0.200 gateway is missing:

$ ip r
default via 192.168.122.1 dev ens3
default via 1.2.3.1 dev ens7.100 metric 1000 onlink
default via 4.5.6.1 dev bond0 metric 2000 onlink
1.2.3.0/24 dev ens7.100 proto kernel scope link src 1.2.3.5
4.5.6.0/24 dev bond0 proto kernel scope link src 4.5.6.8
9.8.7.0/24 dev bond0.200 proto kernel scope link src 9.8.7.7
192.168.122.0/24 dev ens3 proto kernel scope link src 192.168.122.160

After upgrading to vlan version:

$ dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu4

The bond0.200 gateway is present:

$ ip r
default via 192.168.122.1 dev ens3
default via 1.2.3.1 dev ens7.100 metric 1000 onlink
default via 4.5.6.1 dev bond0 metric 2000 onlink
default via 9.8.7.1 dev bond0.200 metric 3000 onlink
1.2.3.0/24 dev ens7.100 proto kernel scope link src 1.2.3.5
4.5.6.0/24 dev bond0 proto kernel scope link src 4.5.6.8
9.8.7.0/24 dev bond0.200 proto kernel scope link src 9.8.7.7
192.168.122.0/24 dev ens3 proto kernel scope link src 192.168.122.160

Additionally, the ens7.100 vlan is correctly configured, even without any ens7 raw device ifupdown config.