what linode puts at /var/lib/coreos-install/user_data

cloud-init.yaml

#cloud-config
users:
 - name: "core"
 - passwd: "***"

# The formatting of the following section is important. Don't change it!
# sytemd-networkd and dhcpcd are both packaged in Container Linux. We'll use systemd
# because that's what's used in the most minimal, out-of-the-box config at this time,
# and dhcpcd is disabled. We're giving systemd a dhcp config file so we can tell it
# to not use IPv6 privacy extensions. We also need DHCP=ipv4 b/c DHCP=all causes
# networking not to come back up on reboots.
write_files:
 - path: "/etc/systemd/network/05-eth0.network"
   permissions: "0644"
   owner: "root"
   content: |
       [Match]
       Name=eth0
       [Network]
       DHCP=ipv4
       Domains=members.linode.com
       IPv6PrivacyExtensions=false