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

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=== 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.

** Affects: netplan
     Importance: Undecided
         Status: Incomplete

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: bionic patch
-- 
systemd-networkd not renaming devices on boot
https://bugs.launchpad.net/bugs/1770082
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