This Heat template spins up three CoreOS Linux instances, configures them via cloud-init/cloud-config to create an etcd cluster and start both etcd and fleet, and configures Docker to listen on a TCP socket. It requires an existing Neutron network, an existing Glance image for CoreOS, a security group allowing the appropriate traffic, and a disc…

coreos-cloud-config.yml

heat_template_version: 2013-05-23
description: >
  A Heat template to add CoreOS instances to an existing network and configure them via cloud-init/cloud-config
parameters:
  network_id:
    type: string
    label: Neutron network ID
    description: ID of existing Neutron network to use
    default: dd6de1d2-735e-4b94-963b-b79aae7bcf1a
  image_id:
    type: string
    label: Glance Image ID
    description: ID of existing Glance image to use
    default: e9695a76-f40d-4f56-bc03-f99031bd81aa
resources:
  coreos_init:
    type: OS::Heat::CloudConfig
    properties:
      cloud_config:
        coreos:
          etcd:
            discovery: https://discovery.etcd.io/7df52496d16c69d0ed03cc48aa2eb6bd
            addr: $private_ipv4:4001
            peer-addr: $private_ipv4:7001
          units:
            - name: etcd.service
              command: start
            - name: fleet.service
              command: start
            - name: docker-tcp.socket
              command: start
              enable: yes
              content: |
                [Unit]
                Description=TCP socket for Docker API
                
                [Socket]
                ListenStream=2345
                BindIPv6Only=both
                Service=docker.service
                
                [Install]
                WantedBy=sockets.target
            - name: enable-docker-tcp.service
              command: start
              content: |
                [Unit]
                Description=Enable TCP socket for Docker API
                
                [Service]
                Type=oneshot
                ExecStart=/usr/bin/systemctl enable docker-tcp.socket
  instance0_port0:
    type: OS::Neutron::Port
    properties:
      admin_state_up: true
      network_id: { get_param: network_id }
      security_groups:
        - 74518432-12ba-4bdb-8d22-09c616b158b0
  instance1_port0:
    type: OS::Neutron::Port
    properties:
      admin_state_up: true
      network_id: { get_param: network_id }
      security_groups:
        - 74518432-12ba-4bdb-8d22-09c616b158b0
  instance2_port0:
    type: OS::Neutron::Port
    properties:
      admin_state_up: true
      network_id: { get_param: network_id }
      security_groups:
        - 74518432-12ba-4bdb-8d22-09c616b158b0
  instance0:
    type: OS::Nova::Server
    properties:
      name: coreos-instance-0
      image: { get_param: image_id }
      flavor: m1.small
      networks:
        - port: { get_resource: instance0_port0 }
      key_name: lab
      user_data_format: RAW
      user_data:
        get_resource: coreos_init
  instance1:
    type: OS::Nova::Server
    properties:
      name: coreos-instance-1
      image: { get_param: image_id }
      flavor: m1.small
      networks:
        - port: { get_resource: instance1_port0 }
      key_name: lab
      user_data_format: RAW
      user_data:
        get_resource: coreos_init
  instance2:
    type: OS::Nova::Server
    properties:
      name: coreos-instance-2
      image: { get_param: image_id }
      flavor: m1.small
      networks:
        - port: { get_resource: instance2_port0 }
      key_name: lab
      user_data_format: RAW
      user_data:
        get_resource: coreos_init