template7

heat_template_version: 2013-05-23
parameters:
  subnet_id:
    type: string
resources:
  mydb:
    type: OS::DBInstance
    properties:
      database_name: wordpress
      database_user: wordpress
      database_password: wordpress_password
      database_root_password: root_password
  cfn_user:
    type: AWS::IAM::User
  web_server_keys:
    type: AWS::IAM::AccessKey
    properties:
      UserName: {get_resource: cfn_user}
  web_server_group:
    type: AWS::AutoScaling::AutoScalingGroup
    properties:
      AvailabilityZones: [nova]
      LaunchConfigurationName: {get_resource: launch_config}
      MinSize: 1
      MaxSize: 3
      LoadBalancerNames:
      - {get_resource: mylb}
  web_server_scaleup_policy:
    type: AWS::AutoScaling::ScalingPolicy
    properties:
      AdjustmentType: ChangeInCapacity
      AutoScalingGroupName: {get_resource: web_server_group}
      Cooldown: 60
      ScalingAdjustment: 1
  web_server_scaledown_policy:
    type: AWS::AutoScaling::ScalingPolicy
    properties:
      AdjustmentType: ChangeInCapacity
      AutoScalingGroupName: {get_resource: web_server_group}
      Cooldown: 60
      ScalingAdjustment: -1
  cpu_alarm_high:
    type: OS::Metering::Alarm
    properties:
      description: Scale-up if the average CPU > 50% for 1 minute
      meter_name: cpu_util
      statistic: avg
      period: 60
      evaluation_periods: 1
      threshold: 50
      alarm_actions:
        - {get_attr: [web_server_scaleup_policy, AlarmUrl]}
      matching_metadata: {'metadata.user_metadata.groupname': {get_resource: web_server_group}}
      comparison_operator: gt
  cpu_alarm_low:
    type: OS::Metering::Alarm
    properties:
      description: Scale-down if the average CPU < 15% for 1 minute
      meter_name: cpu_util
      statistic: avg
      period: 600
      evaluation_periods: 1
      threshold: 15
      alarm_actions:
        - {get_attr: [web_server_scaledown_policy, AlarmUrl]}
      matching_metadata: {'metadata.user_metadata.groupname': {get_resource: web_server_group}}
      comparison_operator: lt
  mymonitor:
    type: OS::Neutron::HealthMonitor
    properties:
      type: TCP
      delay: 3
      max_retries: 5
      timeout: 5
  mypool:
    type: OS::Neutron::Pool
    properties:
      protocol: HTTP
      monitors: [{get_resource: mymonitor}]
      subnet_id: {get_param: subnet_id}
      lb_method: ROUND_ROBIN
      vip:
        protocol_port: 80
  mylb:
    type: OS::Neutron::LoadBalancer
    properties:
      protocol_port: 80
      pool_id: {get_resource: mypool}
  launch_config:
    type: AWS::AutoScaling::LaunchConfiguration
    Metadata:
      AWS::CloudFormation::Init:
        config:
          files:
            /etc/cfn/cfn-credentials:
              content:
                str_replace:
                  template: |
                    AWSAccessKeyId=$key
                    AWSSecretKey=$secret
                  params:
                    $key: {get_resource: web_server_keys}
                    $secret: {get_attr: [web_server_keys, SecretAccessKey]}
              mode: '000400'
              owner: root
              group: root
          packages:
            yum:
              httpd: []
              wordpress: []
          services:
            systemd:
              httpd: {enabled: 'true', ensureRunning: 'true'}
    properties:
      ImageId: Fedora-x86_64-20-20131211.1-sda
      InstanceType: m1.small
      KeyName: heat
      UserData:
        str_replace:
          template: |
            #!/bin/bash -v
            /opt/aws/bin/cfn-init
            firewall-cmd --add-service=http
            firewall-cmd --permanent --add-service=http
            setsebool -P httpd_can_network_connect_db=1

            sed -i "/Deny from All/d" /etc/httpd/conf.d/wordpress.conf
            sed -i "s/Require local/Require all granted/" /etc/httpd/conf.d/wordpress.conf
            sed -i s/database_name_here/wordpress/ /etc/wordpress/wp-config.php
            sed -i s/username_here/wordpress/ /etc/wordpress/wp-config.php
            sed -i s/password_here/wordpress_password/ /etc/wordpress/wp-config.php
            sed -i s/localhost/$db_host/ /etc/wordpress/wp-config.php

            systemctl restart httpd.service
          params:
            $db_host: {get_attr: [mydb, server_address]}

Example template with AutoScaling and Load balancing