インスタンスのフレーバー、ネットワーク設定、イメージ種別を記述した環境テンプレートを作成して、/home/<user>/stacks/example1/cirros.yaml のテンプレートファイルに保存します。<user> の変数は実際のユーザー名に置き換えてください。

heat_template_version: 2016-10-14
description: Template to spawn an cirros instance.

parameters:
  metadata:
    type: json
  image:
    type: string
    description: image used to create instance
    default: cirros
  flavor:
    type: string
    description: instance flavor to be used
    default: m1.tiny
  key_name:
    type: string
    description: keypair to be used
    default: mykeypair
  network:
    type: string
    description: project network to attach instance to
    default: internal1
  external_network:
    type: string
    description: network used for floating IPs
    default: external_network

resources:
  server:
    type: OS::Nova::Server
    properties:
      block_device_mapping:
        - device_name: vda
          delete_on_termination: true
          volume_id: { get_resource: volume }
      flavor: {get_param: flavor}
      key_name: {get_param: key_name}
      metadata: {get_param: metadata}
      networks:
        - port: { get_resource: port }

  port:
    type: OS::Neutron::Port
    properties:
      network: {get_param: network}
      security_groups:
        - default

  floating_ip:
    type: OS::Neutron::FloatingIP
    properties:
      floating_network: {get_param: external_network}

  floating_ip_assoc:
    type: OS::Neutron::FloatingIPAssociation
    properties:
      floatingip_id: { get_resource: floating_ip }
      port_id: { get_resource: port }

  volume:
    type: OS::Cinder::Volume
    properties:
      image: {get_param: image}
      size: 1

~/stacks/example1/environment.yaml に Orchestration のリソースを登録します。

resource_registry:

    "OS::Nova::Server::Cirros": ~/stacks/example1/cirros.yaml

監視する CPU の閾値と追加すべきインスタンス数を記述するスタックテンプレートを作成します。また、インスタンスグループも作成して、このテンプレートに参加することが可能なインスタンス数の最小値および最大値を定義します。

~/stacks/example1/template.yaml に以下の値を保存します。

heat_template_version: 2016-10-14
description: Example auto scale group, policy and alarm
resources:
  scaleup_group:
    type: OS::Heat::AutoScalingGroup
    properties:
      cooldown: 300
      desired_capacity: 1
      max_size: 3
      min_size: 1
      resource:
        type: OS::Nova::Server::Cirros
        properties:
          metadata: {"metering.server_group": {get_param: "OS::stack_id"}}

  scaleup_policy:
    type: OS::Heat::ScalingPolicy
    properties:
      adjustment_type: change_in_capacity
      auto_scaling_group_id: { get_resource: scaleup_group }
      cooldown: 300
      scaling_adjustment: 1

  scaledown_policy:
    type: OS::Heat::ScalingPolicy
    properties:
      adjustment_type: change_in_capacity
      auto_scaling_group_id: { get_resource: scaleup_group }
      cooldown: 300
      scaling_adjustment: -1

  cpu_alarm_high:
    type: OS::Aodh::GnocchiAggregationByResourcesAlarm
    properties:
      description: Scale up if CPU > 80%
      metric: cpu_util
      aggregation_method: mean
      granularity: 300
      evaluation_periods: 1
      threshold: 80
      resource_type: instance
      comparison_operator: gt
      alarm_actions:
        - str_replace:
            template: trust+url
            params:
              url: {get_attr: [scaleup_policy, signal_url]}
      query:
        str_replace:
          template: '{"=": {"server_group": "stack_id"}}'
          params:
            stack_id: {get_param: "OS::stack_id"}

  cpu_alarm_low:
    type: OS::Aodh::GnocchiAggregationByResourcesAlarm
    properties:
      metric: cpu_util
      aggregation_method: mean
      granularity: 300
      evaluation_periods: 1
      threshold: 5
      resource_type: instance
      comparison_operator: lt
      alarm_actions:
        - str_replace:
            template: trust+url
            params:
              url: {get_attr: [scaledown_policy, signal_url]}
      query:
        str_replace:
          template: '{"=": {"server_group": "stack_id"}}'
          params:
            stack_id: {get_param: "OS::stack_id"}

outputs:
  scaleup_policy_signal_url:
    value: {get_attr: [scaleup_policy, signal_url]}

  scaledown_policy_signal_url:
    value: {get_attr: [scaledown_policy, signal_url]}

以下の OpenStack コマンドを実行して環境を構築し、インスタンスをデプロイします。

$ openstack stack create  -t template.yaml -e environment.yaml example
+---------------------+--------------------------------------------+
| Field               | Value                                      |
+---------------------+--------------------------------------------+
| id                  | 248a98bb-f56e-4934-a281-fffde62d78d8       |
| stack_name          | example                                   |
| description         | Example auto scale group, policy and alarm |
| creation_time       | 2017-03-06T15:00:29Z                       |
| updated_time        | None                                       |
| stack_status        | CREATE_IN_PROGRESS                         |
| stack_status_reason | Stack CREATE started                       |
+---------------------+--------------------------------------------+

Orchestration は、スタックを作成して、scaleup_group 定義の min_size パラメーターで指定されている最小数の cirros インスタンスを起動します。インスタンスが正常に作成されたことを確認します。

$ openstack server list
+--------------------------------------+-------------------------------------------------------+--------+------------+-------------+-------------------------------------+
| ID                                   | Name                                                  | Status | Task State | Power State | Networks                            |
+--------------------------------------+-------------------------------------------------------+--------+------------+-------------+-------------------------------------+
| e1524f65-5be6-49e4-8501-e5e5d812c612 | ex-3gax-5f3a4og5cwn2-png47w3u2vjd-server-vaajhuv4mj3j | ACTIVE | -          | Running     | internal1=10.10.10.9, 192.168.122.8 |
+--------------------------------------+-------------------------------------------------------+--------+------------+-------------+-------------------------------------+

Orchestration は、cpu_alarm_high および cpu_alarm_low の定義に従って、スケールアップまたはスケールダウンのイベントをトリガーするのに使用する 2 つの CPU アラームも作成します。トリガーが存在することを確認します。

$ openstack alarm list
+--------------------------------------+--------------------------------------------+-------------------------------------+-------------------+----------+---------+
| alarm_id                             | type                                       | name                                | state             | severity | enabled |
+--------------------------------------+--------------------------------------------+-------------------------------------+-------------------+----------+---------+
| 022f707d-46cc-4d39-a0b2-afd2fc7ab86a | gnocchi_aggregation_by_resources_threshold | example-cpu_alarm_high-odj77qpbld7j | insufficient data | low      | True    |
| 46ed2c50-e05a-44d8-b6f6-f1ebd83af913 | gnocchi_aggregation_by_resources_threshold | example-cpu_alarm_low-m37jvnm56x2t  | insufficient data | low      | True    |
+--------------------------------------+--------------------------------------------+-------------------------------------+-------------------+----------+---------+

load-balancer 環境のプロパティーを記述したテンプレートを作成します。~/stacks/example2/lb-env.yaml に以下の値を入力します。

heat_template_version: 2014-10-16
description: A load-balancer server
parameters:
  image:
    type: string
    description: Image used for servers
  key_name:
    type: string
    description: SSH key to connect to the servers
  flavor:
    type: string
    description: flavor used by the servers
  pool_id:
    type: string
    description: Pool to contact
  user_data:
    type: string
    description: Server user_data
  metadata:
    type: json
  network:
    type: string
    description: Network used by the server

resources:
  server:
    type: OS::Nova::Server
    properties:
      flavor: {get_param: flavor}
      image: {get_param: image}
      key_name: {get_param: key_name}
      metadata: {get_param: metadata}
      user_data: {get_param: user_data}
      networks:
        - port: { get_resource: port }

  member:
    type: OS::Neutron::PoolMember
    properties:
      pool_id: {get_param: pool_id}
      address: {get_attr: [server, first_address]}
      protocol_port: 80

  port:
    type: OS::Neutron::Port
    properties:
      network: {get_param: network}
      security_groups:
        - base

outputs:
  server_ip:
    description: IP Address of the load-balanced server.
    value: { get_attr: [server, first_address] }
  lb_member:
    description: LB member details.
    value: { get_attr: [member, show] }

Web アプリケーションを実行するインスタンス用に別のテンプレートを作成します。以下のテンプレートは、ロードバランサーを作成して、既存のネットワークを使用します。パラメーターは環境に応じて必ず変更し、~/stacks/example2/lb-webserver-rhel7.yaml のようなファイルにテンプレートを保存してください。

heat_template_version: 2014-10-16
description: AutoScaling RHEL 7 Web Application
parameters:
  image:
    type: string
    description: Image used for servers
    default: RHEL 7
  key_name:
    type: string
    description: SSH key to connect to the servers
    default: admin
  flavor:
    type: string
    description: flavor used by the web servers
    default: m2.tiny
  network:
    type: string
    description: Network used by the server
    default: private
  subnet_id:
    type: string
    description: subnet on which the load balancer will be located
    default: 9daa6b7d-e647-482a-b387-dd5f855b88ef
  external_network_id:
    type: string
    description: UUID of a Neutron external network
    default: db17c885-77fa-45e8-8647-dbb132517960

resources:
  webserver:
    type: OS::Heat::AutoScalingGroup
    properties:
      min_size: 1
      max_size: 3
      cooldown: 60
      desired_capacity: 1
      resource:
        type: file:///etc/heat/templates/lb-env.yaml
        properties:
          flavor: {get_param: flavor}
          image: {get_param: image}
          key_name: {get_param: key_name}
          network: {get_param: network}
          pool_id: {get_resource: pool}
          metadata: {"metering.stack": {get_param: "OS::stack_id"}}
          user_data:
            str_replace:
              template: |
                #!/bin/bash -v

                yum -y install httpd php
                systemctl enable httpd
                systemctl start httpd
                cat <<EOF > /var/www/html/hostname.php
                <?php echo "Hello, My name is " . php_uname('n'); ?>
                EOF
              params:
                hostip: 192.168.122.70
                fqdn: sat6.example.com
                shortname: sat6

  web_server_scaleup_policy:
    type: OS::Heat::ScalingPolicy
    properties:
      adjustment_type: change_in_capacity
      auto_scaling_group_id: {get_resource: webserver}
      cooldown: 60
      scaling_adjustment: 1

  web_server_scaledown_policy:
    type: OS::Heat::ScalingPolicy
    properties:
      adjustment_type: change_in_capacity
      auto_scaling_group_id: {get_resource: webserver}
      cooldown: 60
      scaling_adjustment: -1

  monitor:
    type: OS::Neutron::HealthMonitor
    properties:
      type: TCP
      delay: 5
      max_retries: 5
      timeout: 5

  pool:
    type: OS::Neutron::Pool
    properties:
      protocol: HTTP
      monitors: [{get_resource: monitor}]
      subnet_id: {get_param: subnet_id}
      lb_method: ROUND_ROBIN
      vip:
        protocol_port: 80

  lb:
    type: OS::Neutron::LoadBalancer
    properties:
      protocol_port: 80
      pool_id: {get_resource: pool}

  lb_floating:
    type: OS::Neutron::FloatingIP
    properties:
      floating_network_id: {get_param: external_network_id}
      port_id: {get_attr: [pool, vip, port_id]}

outputs:
  scale_up_url:
    description: >
      This URL is the webhook to scale up the autoscaling group.  You
      can invoke the scale-up operation by doing an HTTP POST to this
      URL; no body nor extra headers are needed.
    value: {get_attr: [web_server_scaleup_policy, alarm_url]}
  scale_dn_url:
    description: >
      This URL is the webhook to scale down the autoscaling group.
      You can invoke the scale-down operation by doing an HTTP POST to
      this URL; no body nor extra headers are needed.
    value: {get_attr: [web_server_scaledown_policy, alarm_url]}
  pool_ip_address:
    value: {get_attr: [pool, vip, address]}
    description: The IP address of the load balancing pool
  website_url:
    value:
      str_replace:
        template: http://serviceip/hostname.php
        params:
          serviceip: { get_attr: [lb_floating, floating_ip_address] }
    description: >
      This URL is the "external" URL that can be used to access the
      website.
  gnocchi_query:
    value:
      str_replace:
        template: >
            gnocchi measures aggregation --query 'server_group="stackval"'
            --granularity 300 --aggregation mean cpu_util
        params:
          stackval: { get_param: "OS::stack_id" }
    description: >
      This is a gnocchi query for statistics on the cpu_util meter
      Samples about OS::Nova::Server instances in this stack.
      The --query parameter selects Samples according to the subject's metadata.
      When a VM's metadata includes an item of the form metering.X=Y,
      the corresponding gnocchi resource has a metadata item of the
      form user_metadata.X=Y and samples about resources so tagged can
      be queried with a gnocchi query term of the form
      metadata.user_metadata.X=Y.  In this case the nested stacks give
      their VMs metadata that is passed as a nested stack parameter,
      and this stack passes a metadata of the form metering.stack=Y,
      where Y is this stack's ID.

Telemetry のデータ収集の間隔を更新します。デフォルトでは、Telemetry はインスタンスを 10 分ごとにポーリングして、CPU のデータを取得します。以下の例では、/etc/ceilometer/pipeline.yaml で、この間隔を 60 秒に変更します。

- name: cpu_source
interval: 60
meters:
- "cpu"
sinks:
- cpu_sink

OpenStack ceilometer の全サービスを再起動して、更新された Telemetry の設定を適用します。

# systemctl restart openstack-ceilometer*

Orchestration のスクリプトを実行します。このスクリプトにより、環境が構築され、テンプレートを使用してインスタンスがデプロイされます。

# heat stack-create webfarm -f /root/lb-webserver-rhel7.yaml

/root/lb-webserver-rhel7.yaml の箇所は、実際のパスとファイル名に変更してください。