{

"Parameters": {
  "MinFrontendsVar": {"Type": "Number", "MinValue": "0", "Default": "0"},
  "MaxFrontendsVar": {"Type": "Number", "MinValue": "1", "Default": "1"}
},


"Resources": {

"Frontends": {
  "Type": "AWS::AutoScaling::AutoScalingGroup",

  "UpdatePolicy": {
    "AutoScalingRollingUpdate": {
      "MinInstancesInService": {"Ref": "MinFrontendsVar"},
      "MaxBatchSize": "1",
      "PauseTime": "PT0S"
    }
  },

  "Properties": {
    "AvailabilityZones": [
      {"Fn::GetAtt": ["SubnetA", "AvailabilityZone"]},
      {"Fn::GetAtt": ["SubnetB", "AvailabilityZone"]},
      {"Fn::GetAtt": ["SubnetC", "AvailabilityZone"]}
    ],
    "VPCZoneIdentifier": [
      {"Ref": "SubnetA"},
      {"Ref": "SubnetB"},
      {"Ref": "SubnetC"}
    ],
    "LaunchConfigurationName": {"Ref": "FrontendLaunchConfiguration"},

    "MinSize": {"Ref": "MinFrontendsVar"},
    "MaxSize": {"Ref": "MaxFrontendsVar"},
    "DesiredCapacity": {"Ref": "MinFrontendsVar"},

    "HealthCheckType": "ELB",
    "HealthCheckGracePeriod": "1600",
    "LoadBalancerNames": [
      {"Ref": "ClientAPILoadBalancer"}
    ],

    "TerminationPolicies": ["OldestLaunchConfiguration", "OldestInstance"],

    "MetricsCollection": [{
      "Granularity": "1Minute",
      "Metrics": ["GroupMinSize", "GroupMaxSize"]
    }]
  }
},

"FrontendLaunchConfiguration" : {
  "Type" : "AWS::AutoScaling::LaunchConfiguration",
  "DependsOn": "InternetConnection",

  "Metadata": {
    "AWS::CloudFormation::Init": {}
  },

  "Properties" : {
    "InstanceType": "m3.medium",
    "ImageId": {"Ref": "InstanceAMIVar"},

    "KeyName": {"Ref": "IAMKeypairNameVar"},
    "SecurityGroups": [{"Ref": "FrontendSecurityGroup"}],

    "AssociatePublicIpAddress": "true",

    "UserData": {"Fn::Base64": {"Fn::Join": ["", [
      "#!/bin/bash\n",
      "export CFN_REGION='", {"Ref": "AWS::Region"}, "'\n",
      "export CFN_STACK_NAME='", {"Ref": "AWS::StackName"}, "'\n",
      "export CFN_INSTANCE_LOGICAL_NAME='FrontendLaunchConfiguration'\n",
      "export CFN_INSTANCE_HOSTNAME='", {"Fn::FindInMap": ["StackZoneRecords", "ClientAPI", "DNSName"]}, "'\n",
      "export BEXNG_ADMIN_API_HOST='", {"Fn::FindInMap": ["StackZoneRecords", "AdminAPI", "DNSName" ]}, "'\n",
      {"Ref": "UserDataEnvironmentVar"}, "\n",
      {"Ref": "CommonRoleScriptVar"}, "\n",
      {"Ref": "FrontendRoleScriptVar"}, "\n"
    ]]}}
  }
}

}

}