CoreOS Cloud-Init with host announcement service

coreos-cloud-init-host-announce

#cloud-config
ssh_authorized_keys:
  - ssh-rsa AAAAB3NzaC1yc2EAAAADAQAB ...snip... QAyapHGwoBvkq7nNp
coreos:
  etcd:
      # via https://discovery.etcd.io/new
      discovery: https://discovery.etcd.io/7028e012ca66ef0121b64c19c40a425a
      addr: $private_ipv4:4001
      peer-addr: $private_ipv4:7001
  units:
    - name: etcd.service
      command: start
    - name: fleet.service
      command: start
      runtime: no
      content: |
        [Unit]
        Description=fleet
        [Service]
        Environment=FLEET_PUBLIC_IP=$private_ipv4
        ExecStart=/usr/bin/fleet
    - name: host.service
      command: start
      runtime: no
      content: |
        [Unit]
        Description=Host announcer
        After=etcd.service
        Requires=etcd.service
        [Service]
        Environment=COREOS_PRIVATE_IPV4=$private_ipv4
        ExecStart=/bin/bash -c "while true; do echo setting host %b to $COREOS_PRIVATE_IPV4; etcdctl set /hosts/%m $COREOS_PRIVATE_IPV4 --ttl 60; sleep 45; done"
        ExecStop=/usr/bin/etcdctl rm /hosts/%m
        [X-Fleet]
        X-Conflicts=host.service
write_files:
  - content: |
      ssh-rsa AAAAB3NzaC1yc2EAAAADAQAB ...snip... QAyapHGwoBvkq7nNp
    path: /home/core/.ssh/shared.pub
    permissions: '0600'
    owner: core:core
  - content: |
      -----BEGIN RSA PRIVATE KEY-----
      MIIEowIBAAKCAQEAsjvCcWeXSpB2EvTvxsyMHoA55BDcU/oP0Kr1QvgXGmw/PT/R
      8Nq/Hy8WBW8vlJGqlkClZqvJn7vE014G3a4otmJT087nA+ftfYc0g04GzBFzt05Q
      ... snip ...
      dWtYdrxBBuKUDmSqdHkGPJS/KErmVm2OWqPgiOMgae2s7QSrySX6VKRH/grV0DLh
      UYrPiHUruKX6rgEVjhzS55dKiN4XRk0N+CWYXq3mgmO5zV3rb4/u
      -----END RSA PRIVATE KEY-----
    path: /home/core/.ssh/shared
    permissions: '0600'
    owner: core:core