Comment 0 for bug 1770082

'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 crazy3 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.