[Bug 1820929] Re: netplan should consider adding more udev attribute for exact matching of failover 3-netdev interfaces

[Si-Wei Liu]

Thanks, Jay. Sorry for getting back late.

I just tested it on an 18.04.5 Ubuntu image, and just as you mentioned
it's working as expected. I think we can close this bug.

# ip l
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens3: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 12:3f:bd:fd:bb:1e brd ff:ff:ff:ff:ff:ff
3: ens3nsby: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master ens3 state UP mode DEFAULT group default qlen 1000
    link/ether 12:3f:bd:fd:bb:1e brd ff:ff:ff:ff:ff:ff
4: ens4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master ens3 state UP mode DEFAULT group default qlen 1000
    link/ether 12:3f:bd:fd:bb:1e brd ff:ff:ff:ff:ff:ff

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Title:
  netplan should consider adding more udev attribute for exact matching
  of failover 3-netdev interfaces

Status in netplan:
  Triaged
Status in initramfs-tools package in Ubuntu:
  New
Status in netplan.io package in Ubuntu:
  Triaged
Status in systemd package in Ubuntu:
  Incomplete
Status in initramfs-tools source package in Bionic:
  Fix Released
Status in netplan.io source package in Bionic:
  New
Status in systemd source package in Bionic:
  New

Bug description:
  [Impact]

  * At present, virtual machines utilizing net_failover network
  interface configurations are incorrectly configured due to the
  reliance on the MAC address to identify specific network interfaces.
  When net_failover is utilized, multiple interfaces will bear the same
  MAC address (the net_failover master itself, as well as the interfaces
  subordinate to it), rendering the MAC address ineffective for unique
  identification of the interface.  This results in incorrect naming of
  network interfaces from the "set-name" directive in the netplan
  configuration.

  * The solution here is to use the interface name instead of the MAC
  address when the interface is a net_failover master device.  Logic is
  added on initramfs-tools to check the device type and virtio flags to
  apply this change only to net_failover master devices.

  [Test Case]

  * The change can be tested by configuring a virtual machine with a
  virtio_net network device with the "failover=on" option to the
  "-device" option to qemu, e.g.,

  -device virtio-net-
  pci,netdev=hostnet0,id=net0,bus=pci.0,addr=0x3,mac=00:00:17:00:18:04,failover=on

  * This will set the virtio device "standby" feature bit (bit 62,
  counting from 0).  This requires a version of qemu with support for
  this feature.

  * When so configured, the netplan configuration generated by initramfs
  will not contain a "macaddress:" match directive for the network
  interface in question.

  [Regression Potential]

  * Erroneous identification of a network interface as a net_failover
  master device could lead to omission of a macaddress directive,
  causing interfaces to be incorrectly named.

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