Comment 10 for bug 1771704

Verification done on bionic with netplan.io 0.40.1~18.04.2:

I have checked that with ipv4 link-local enabled as per the use-case, an ipv4 link-local address is correctly set up by systemd-networkd as requested by the netplan config.

ubuntu@nice-baboon:~$ sudo vi /etc/netplan/50-cloud-init.yaml
ubuntu@nice-baboon:~$ sudo netplan --debug apply
cat /** (generate:1270): DEBUG: 18:23:59.386: Processing input file /etc/netplan/50-cloud-init.yaml..
** (generate:1270): DEBUG: 18:23:59.386: starting new processing pass
** (generate:1270): DEBUG: 18:23:59.387: ens3: setting default backend to 1
** (generate:1270): DEBUG: 18:23:59.387: Generating output files..
** (generate:1270): DEBUG: 18:23:59.387: NetworkManager: definition ens3 is not for us (backend 1)
DEBUG:netplan generated networkd configuration exists, restarting networkd
DEBUG:no netplan generated NM configuration exists
eDEBUG:ens3 not found in {}
DEBUG:Merged config:
network:
  bonds: {}
  bridges: {}
  ethernets:
    ens3:
      addresses:
      - 10.3.21.29/20
      gateway4: 10.3.16.1
      link-local:
      - ipv4
      match:
        macaddress: 52:54:00:4d:3e:84
      mtu: 1500
      nameservers:
        addresses:
        - 10.3.21.25
        search:
        - cloud.cyphermox.net
  vlans: {}
  wifis: {}

DEBUG:device lo operstate is unknown, not changing
DEBUG:device ens3 operstate is up, not changing
DEBUG:{}
DEBUG:netplan triggering .link rules for lo
DEBUG:netplan triggering .link rules for ens3
tubuntu@nice-baboon:~$ ip addr
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,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 52:54:00:4d:3e:84 brd ff:ff:ff:ff:ff:ff
    inet 169.254.4.84/16 brd 169.254.255.255 scope link ens3
       valid_lft forever preferred_lft forever
    inet 10.3.21.29/20 brd 10.3.31.255 scope global ens3
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe4d:3e84/64 scope link
       valid_lft forever preferred_lft forever