AWS user-data cloud-config for autoscaling etcd2 masters

etcd2-cluster-master

coreos:
  flannel:
    interface: $private_ipv4
    etcd_endpoints: http://127.0.0.1:2379
  etcd2:
    advertise-client-urls: http://$private_ipv4:2379
    initial-advertise-peer-urls: http://$private_ipv4:2380
    listen-client-urls: http://0.0.0.0:2379
    listen-peer-urls: http://$private_ipv4:2380
  units:
    - name: etcd2-peers.service
      command: start
      content: |
        [Unit]
        Description=Set etcd2 peers
        [Service]
        Type=oneshot
        RemainAfterExit=yes
        ExecStartPre=/usr/bin/mkdir -p /etc/sysconfig
        ExecStart=/usr/bin/rkt --insecure-options=image run --dns 8.8.8.8 --net=host --volume data,kind=host,source=/etc/sysconfig/ --mount volume=data,target=/etc/sysconfig/ docker://monsantoco/etcd-aws-cluster
    - name: etcd2.service
      command: start
      drop-ins:
        - name: 30-etcd_peers.conf
          content: |
            [Unit]
            After=etcd2-peers.service
            Requires=etcd2-peers.service
            [Service]
            EnvironmentFile=/etc/sysconfig/etcd-peers

More about this here: https://metabroadcast.com/blog/getting-etcd2-to-play-nicely