• Boot from ISO
• Configure ssh key for 'core' user. Paste your own SSH pub. key into a YAML config file, additionally configure hostname and other users. See https://coreos.com/docs/cluster-management/setup/cloudinit-cloud-config/ for all options.

  $ sudo su -
  # vi config
  
  #cloud-config
  hostname: coreos1
  
  ssh_authorized_keys:
    - ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC0g+ZTxC7weoIJLUafOgrm+h...

• Install CoreOS.

  coreos-install -d /dev/sda -c ~/config

• Log in with the core use (using the dhcp requested IP-address).
• Configure static networking.

  cd /etc/systemd/network/
  vi static.network
  
  [Match]
  Name=ens3
  
  [Network]
  Address=192.168.0.15/24
  Gateway=192.168.0.1
  DNS=1.2.3.4
  DNS=2.3.4.5

• Apply config.

  sudo systemctl restart systemd-networkd

• Add users via cloud-config.

  #cloud-config
  
  users:
    - name: elroy
      passwd: $6$5s2u6/jR$un0AvWnqilcgaNB3Mkxd5yYv6mTlWfOoCYHZmfi3LDKVltj.E8XNKEcwWm...
      groups:
        - sudo
        - docker
      ssh-authorized-keys:
        - ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC0g+ZTxC7weoIJLUafOgrm+h...

#cloud-config
coreos:
  update:
    reboot-strategy: reboot