CloudFormation Example

cf.json

{
  "AWSTemplateFormatVersion": "2010-09-09",

  "Description": "Role: Renderer. Amazon CloudFormation Template",

  "Parameters": {
    "AMI":{
      "Description":"The AMI You want to use",
      "Type":"String",
      "Default":"ami-8fc476e6"
    },
    "InstanceType": {
      "Description": "Renderer Server EC2 Instance Type",
      "Type": "String",
      "Default": "c1.xlarge",
      "AllowedValues": ["c1.medium","c1.xlarge","cc1.4xlarge","cc2.8xlarge","cg1.4xlarge"],
      "ConstraintDescription": "must be a valid EC2 instance type"
    },
    "KeyName": {
      "Description": "Name of an existing EC2 Keypair to enable access to the machine",
      "Type": "String",
      "Default": "sw-production-east-va"
    }
  },  

  "Resources": {
    "RendererServerGroup": {
      "Type": "AWS::AutoScaling::AutoScalingGroup",
      "Properties": {
        "AvailabilityZones": { "Fn::GetAZs": "" },
        "LaunchConfigurationName": { "Ref": "LaunchConfig" },
        "MinSize": "2",
        "MaxSize": "16",
        "Tags": [
          { "Key": "Environment", "Value": "Production", "PropagateAtLaunch": "true" },
          { "Key": "Role", "Value": "renderer", "PropagateAtLaunch": "true" }
        ]
      }
    },

    "LaunchConfig": {
      "Type": "AWS::AutoScaling::LaunchConfiguration",
      "Properties": {
        "KeyName": { "Ref": "KeyName" },
        "ImageId" : {"Ref":"AMI"},
        "SecurityGroups": [ { "Ref": "InstanceSecurityGroup" }],
        "InstanceType": { "Ref": "InstanceType" }
      }
    },

    "RendererServerScaleUpPolicy" : {
      "Type" : "AWS::AutoScaling::ScalingPolicy",
      "Properties" : {
        "AdjustmentType" : "ChangeInCapacity",
        "AutoScalingGroupName" : { "Ref" : "RendererServerGroup" },
        "Cooldown" : "300",
        "ScalingAdjustment" : "6"
      }
    },

    "RendererServerScaleDownPolicy" : {
      "Type" : "AWS::AutoScaling::ScalingPolicy",
      "Properties" : {
        "AdjustmentType" : "ChangeInCapacity",
        "AutoScalingGroupName" : { "Ref" : "RendererServerGroup" },
        "Cooldown" : "300",
        "ScalingAdjustment" : "-1"
      }
    },

    "ScaleUpAlarm": {
     "Type": "AWS::CloudWatch::Alarm",
     "Properties": {
        "AlarmDescription": "Hit it with a hammer",
        "MetricName": "Prod-VideoRenderQueueLength",
        "Namespace": "DatCompany",
        "Statistic": "Average",
        "Period": "60",
        "EvaluationPeriods": "2",
        "Threshold": "60",
        "AlarmActions": [ { "Ref": "RendererServerScaleUpPolicy" } ],        
        "ComparisonOperator": "GreaterThanThreshold"
      }
    },

    "ScaleDownAlarm": {
     "Type": "AWS::CloudWatch::Alarm",
     "Properties": {
        "AlarmDescription": "Simmer Down",
        "MetricName": "Prod-VideoRenderQueueLength",
        "Namespace": "DatCompany",
        "Statistic": "Average",
        "Period": "60",
        "EvaluationPeriods": "5",
        "Threshold": "30",
        "AlarmActions": [ { "Ref": "RendererServerScaleDownPolicy" } ],
        "ComparisonOperator": "LessThanThreshold"
      }
    },

    "InstanceSecurityGroup": {
      "Type": "AWS::EC2::SecurityGroup",
      "Properties": {
        "GroupDescription": "Enable SSH access to the configured server",
        "SecurityGroupIngress" : [
          { "IpProtocol": "tcp", "FromPort": "22", "ToPort": "22", "CidrIp": "0.0.0.0/0" }
        ]
      }
    }
  }
}