$ lxc exec bionic-demo -- grep -v '^#' /etc/netplan/50-cloud-init.yaml
network:
    version: 2
    ethernets:
        accept-ra: 'no'
        eth0:
            dhcp4: true


$ lxc exec bionic-demo -- sh -c 'for p in /run/systemd/network/*; do
     echo == $p ==; cat $p; done'
== /run/systemd/network/10-netplan-eth0.network ==
[Match]
Name=eth0

[Network]
DHCP=ipv4

[DHCP]
UseMTU=true
RouteMetric=100


$ lxc exec bionic-demo  -- systemctl status --no-pager --full systemd-networkd
● systemd-networkd.service - Network Service
   Loaded: loaded (/lib/systemd/system/systemd-networkd.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2017-11-13 19:02:12 UTC; 6min ago
     Docs: man:systemd-networkd.service(8)
 Main PID: 115 (systemd-network)
   Status: "Processing requests..."
    Tasks: 1 (limit: 4915)
   Memory: 1.8M
      CPU: 20ms
   CGroup: /system.slice/systemd-networkd.service
           └─115 /lib/systemd/systemd-networkd

Nov 13 19:02:12 bionic-demo systemd[1]: systemd-networkd.service: Failed to set invocation ID on control group /system.slice/systemd-networkd.service, ignoring: Operation not permitted
Nov 13 19:02:12 bionic-demo systemd[1]: Starting Network Service...
Nov 13 19:02:12 bionic-demo systemd-networkd[115]: Enumeration completed
Nov 13 19:02:12 bionic-demo systemd[1]: Started Network Service.
Nov 13 19:02:12 bionic-demo systemd-networkd[115]: eth0: DHCPv4 address 10.75.205.187/24 via 10.75.205.1
Nov 13 19:02:12 bionic-demo systemd-networkd[115]: Not connected to system bus, ignoring transient hostname.
Nov 13 19:02:13 bionic-demo systemd-networkd[115]: eth0: Gained IPv6LL
Nov 13 19:02:13 bionic-demo systemd-networkd[115]: eth0: Configured
Nov 13 19:02:13 bionic-demo systemd-networkd[115]: eth0: DHCPv6 address fd42:eee5:7c43:3d62:6f4:155b:39cc:fc3d/128 timeout preferred 3600 valid 3600
Nov 13 19:02:42 bionic-demo systemd-networkd[115]: Could not set hostname: Method call timed out