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

  "Description" : "AWS CloudFormation Sample Template ELBWithLockedDownEC2Instances: Create a load balanced, Auto Scaled sample website where the instances are locked down to only accept traffic from the load balancer. This example creates an Auto Scaling group behind a load balancer with a simple health check. The web site is available on port 80, however, the instances can be configured to listen on any port (8888 by default). **WARNING** This template creates one or more Amazon EC2 instances and an Elastic Load Balancer. You will be billed for the AWS resources used if you create a stack from this template.",

  "Parameters" : {
    "InstanceType" : {
      "Description" : "WebServer EC2 instance type",
      "Type" : "String",
      "Default" : "m1.small",
      "AllowedValues" : [ "t1.micro","m1.small","m1.medium","m1.large","m1.xlarge","m2.xlarge","m2.2xlarge","m2.4xlarge","m3.xlarge","m3.2xlarge","c1.medium","c1.xlarge","cc1.4xlarge","cc2.8xlarge","cg1.4xlarge"],
      "ConstraintDescription" : "must be a valid EC2 instance type."
    },

    "WebServerPort" : {
      "Description" : "TCP/IP port of the web server",
      "Type" : "String",
      "Default" : "8888"
    }
  },

  "Mappings" : {
    "AWSInstanceType2Arch" : {
      "t1.micro"    : { "Arch" : "64" },
      "m1.small"    : { "Arch" : "64" },
      "m1.medium"   : { "Arch" : "64" },
      "m1.large"    : { "Arch" : "64" },
      "m1.xlarge"   : { "Arch" : "64" },
      "m2.xlarge"   : { "Arch" : "64" },
      "m2.2xlarge"  : { "Arch" : "64" },
      "m2.4xlarge"  : { "Arch" : "64" },
      "m3.xlarge"   : { "Arch" : "64" },
      "m3.2xlarge"  : { "Arch" : "64" },
      "c1.medium"   : { "Arch" : "64" },
      "c1.xlarge"   : { "Arch" : "64" }
    },

    "AWSRegionArch2AMI" : {
      "us-east-1"      : { "32" : "ami-aba768c2", "64" : "ami-81a768e8" },
      "us-west-1"      : { "32" : "ami-458fd300", "64" : "ami-b18ed2f4" },
      "us-west-2"      : { "32" : "ami-fcff72cc", "64" : "ami-feff72ce" },
      "eu-west-1"      : { "32" : "ami-018bb975", "64" : "ami-998bb9ed" },
      "sa-east-1"      : { "32" : "ami-a039e6bd", "64" : "ami-a239e6bf" },
      "ap-southeast-1" : { "32" : "ami-425a2010", "64" : "ami-5e5a200c" },
      "ap-southeast-2" : { "32" : "ami-f98512c3", "64" : "ami-43851279" },
      "ap-northeast-1" : { "32" : "ami-7871c579", "64" : "ami-7671c577" }
    }
},

  "Resources" : {
    "WebServerGroup" : {
      "Type" : "AWS::AutoScaling::AutoScalingGroup",
      "Properties" : {
        "AvailabilityZones" : { "Fn::GetAZs" : "" },
        "LaunchConfigurationName" : { "Ref" : "LaunchConfig" },
        "MinSize" : "2",
        "MaxSize" : "2",
        "LoadBalancerNames" : [ { "Ref" : "ElasticLoadBalancer" } ]
      }
    },

    "LaunchConfig" : {
      "Type" : "AWS::AutoScaling::LaunchConfiguration",
      "Properties" : {
        "ImageId" : { "Fn::FindInMap" : [ "AWSRegionArch2AMI", { "Ref" : "AWS::Region" },
                                          { "Fn::FindInMap" : [ "AWSInstanceType2Arch", { "Ref" : "InstanceType" },
                                          "Arch" ] } ] },
        "UserData" : { "Fn::Base64" : { "Ref" : "WebServerPort" }},
        "SecurityGroups" : [ { "Ref" : "InstanceSecurityGroup" } ],
        "InstanceType" : { "Ref" : "InstanceType" }
      }
    },

    "ElasticLoadBalancer" : {
      "Type" : "AWS::ElasticLoadBalancing::LoadBalancer",
      "Properties" : {
        "AvailabilityZones" : { "Fn::GetAZs" : "" },
        "Listeners" : [ {
          "LoadBalancerPort" : "80",
          "InstancePort" : { "Ref" : "WebServerPort" },
          "Protocol" : "HTTP"
        } ],
        "HealthCheck" : {
          "Target" : { "Fn::Join" : [ "", ["HTTP:", { "Ref" : "WebServerPort" }, "/"]]},
          "HealthyThreshold" : "3",
          "UnhealthyThreshold" : "5",
          "Interval" : "30",
          "Timeout" : "5"
        }
      }
    },

    "InstanceSecurityGroup" : {
      "Type" : "AWS::EC2::SecurityGroup",
      "Properties" : {
        "GroupDescription" : "Enable SSH access and HTTP access on the inbound port",
        "SecurityGroupIngress" : [ {
          "IpProtocol" : "tcp",
          "FromPort" : { "Ref" : "WebServerPort" },
          "ToPort" : { "Ref" : "WebServerPort" },
          "SourceSecurityGroupOwnerId" : {"Fn::GetAtt" : ["ElasticLoadBalancer", "SourceSecurityGroup.OwnerAlias"]},
          "SourceSecurityGroupName" : {"Fn::GetAtt" : ["ElasticLoadBalancer", "SourceSecurityGroup.GroupName"]}
        } ]
      }
    }
  },

  "Outputs" : {
    "URL" : {
      "Description" : "URL of the website",
      "Value" :  { "Fn::Join" : [ "", [ "http://", { "Fn::GetAtt" : [ "ElasticLoadBalancer", "DNSName" ]}]]}
    }
  }
}