[Bug 1770082] Re: systemd-networkd not renaming devices on boot

[Ryan Harper]

I'm just verifying that on my end;  note that the 99-default.link is
going to be sufficient to trigger a rename from eth0 to ens3; which
then prevents any rename once we mount root.

Here's the trigger:

% /usr/share/initramfs-tools/hooks/udev
# copy .link files containing interface naming definitions
mkdir -p $DESTDIR/lib/systemd/network/
find /lib/systemd/network -name '*.link' -execdir cp -pt
$DESTDIR/lib/systemd/network/ '{}' +
if [ -d /etc/systemd/network ]; then
  find /etc/systemd/network -name '*.link' -execdir cp -pt
$DESTDIR/lib/systemd/network/ '{}' +
fi

If you create a .link file in /etc/systemd/network/ lower than 99-*
then those link rules will apply first.


On Fri, May 11, 2018 at 9:24 AM, Daniel Axtens
<daniel.axtens at canonical.com> wrote:
> Ok, so the bit I'm stuck on is how the link files and the netplan
> generator are getting pulled into the initramfs then.
>
> ubuntu at btest:~$ sudo update-initramfs -u
> update-initramfs: Generating /boot/initrd.img-4.15.0-20-generic
>
> ubuntu at btest:~$ lsinitramfs /boot/initrd.img-4.15.0-20-generic | grep \\.link
> lib/systemd/network/99-default.link
> ubuntu at btest:~$ lsinitramfs /boot/initrd.img-4.15.0-20-generic | grep netplan
> ubuntu at btest:~$ lsinitramfs /boot/initrd.img-4.15.0-20-generic | grep generate
> ubuntu at btest:~$ lsinitramfs /boot/initrd.img-4.15.0-20-generic | grep system-generators
>
> As you can see there's no generator and no link files in my initramfs -
> by what mechanism is it supposed to work? What package/script/tool is
> supposed to pull the link files in?
>
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> https://bugs.launchpad.net/bugs/1770082
>
> Title:
>   systemd-networkd not renaming devices on boot
>
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https://bugs.launchpad.net/bugs/1770082

Title:
  systemd-networkd not renaming devices on boot

Status in netplan:
  Incomplete
Status in systemd package in Ubuntu:
  New

Bug description:
  === systemd issue ===

  Renaming devices doesn't seem to work.

  If I disable all other network configuration and create
  /etc/systemd/network/10-network.link with:

  [Match]
  MACAddress=52:54:00:c1:c9:bb

  [Link]
  Name=myiface3

  I expect this to cause the device with that MAC address to be renamed
  to  myiface3. However, when I reboot, I instead see:

  $ 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,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
      link/ether 52:54:00:c1:c9:bb brd ff:ff:ff:ff:ff:ff

  The device is not renamed.

  This link file is pretty much identical to Example 2 in
  https://www.freedesktop.org/software/systemd/man/systemd.link.html.

  The renaming does work if I boot with net.ifnames=0, and oddly, it
  also works if I unbind the device and rebind it as netplan apply does.
  No setting of NamePolicy seems to help.

  === Original Bug ==

  'set-name:' doesn't change the name of a network interface on boot, it
  only works when you do netplan apply.

  Say I take this 50-cloud-init.yaml file:

  # This file is generated from information provided by
  # the datasource.  Changes to it will not persist across an instance.
  # To disable cloud-init's network configuration capabilities, write a file
  # /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
  # network: {config: disabled}
  network:
      version: 2
      ethernets:
          ens3:
              dhcp4: true
              match:
                  macaddress: 52:54:00:de:bd:f6
              set-name: ens3

  Say I change set-name to 'myiface3' and reboot. I expect that the
  device will be called myiface3 and brought up fine with dhcp. However,
  instead I see:

  $ ip a
  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
         valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
         valid_lft forever preferred_lft forever
  2: ens3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
      link/ether 52:54:00:de:bd:f6 brd ff:ff:ff:ff:ff:ff

  The name has not been changed, and the device has not been brought up.

  If I run netplan apply however, I see the following:

  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
      link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
      inet 127.0.0.1/8 scope host lo
         valid_lft forever preferred_lft forever
      inet6 ::1/128 scope host
         valid_lft forever preferred_lft forever
  3: myiface3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
      link/ether 52:54:00:de:bd:f6 brd ff:ff:ff:ff:ff:ff
      inet 192.168.122.151/24 brd 192.168.122.255 scope global dynamic myiface3
         valid_lft 3575sec preferred_lft 3575sec
      inet6 fe80::5054:ff:fede:bdf6/64 scope link
         valid_lft forever preferred_lft forever

  So names are successfully changed with netplan apply.

  This seems to be some udev-related timing or priority issue that I'm
  still trying to hunt down.

  This breaks some forms of migration in certain cloud environments.

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