AWS CloudFormation template with 3 different instance 'types' (Server, Agent, Relay) I'm using AutoScaling to dynamically launch X number of instances of a type.

Cloud-Formation template

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

"Description" : "uDeploy Agent-Relay-Server",

"Parameters" : {
    "keyName" : {
        "Description" : "SSH key to enable access on the servers",
        "Type" : "String",
        "Default" : "nick-portal"
    },

    "ServerInstanceCount" : {
        "Description" : "Number of Servers to start",
        "Type" : "Number",
        "Default" : "1"
    },
    "RelayInstanceCount" : {
        "Description" : "Number of Agent Relays to start",
        "Type" : "Number",
        "Default" : "2"
    },
    "AgentInstanceCount" : {
        "Description" : "Number of Agents to start",
        "Type" : "Number",
        "Default" : "4"
    },

    "ServerAMI" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "ami-7539b41c"
    },
    "RelayAMI" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "ami-7539b41c"
    },
    "AgentAMI" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "ami-7539b41c"
    },

    "ServerUserData" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "#!/bin/bash"
    },
    "RelayUserData" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "#!/bin/bash"
    },
    "AgentUserData" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "#!/bin/bash"
    },
    "Zone" : {
        "Description" : "",
        "Type" : "String",
        "Default" : "us-east-1d"
    }
},

"Resources" : {
    "ServerLaunchConfig" : { 
        "Type" : "AWS::AutoScaling::LaunchConfiguration",
        "Properties" : {
            "KeyName" : { "Ref" : "keyName" },
            "ImageId" : { "Ref" : "ServerAMI" },
            "UserData" : { "Fn::Base64" : { "Ref" : "ServerUserData" } },
            "SecurityGroups" : [ { "Ref" : "ServerSecurityGroup" }, { "Ref" : "SshSecurityGroup" } ],
            "InstanceType" : "t1.micro"
        }
    },
    "RelayLaunchConfig" : { 
        "Type" : "AWS::AutoScaling::LaunchConfiguration",
        "Properties" : {
            "KeyName" : { "Ref" : "keyName" },
            "ImageId" : { "Ref" : "RelayAMI" },
            "UserData" : { "Fn::Base64" : { "Ref" : "RelayUserData" } },
            "SecurityGroups" : [ { "Ref" : "RelaySecurityGroup" }, { "Ref" : "SshSecurityGroup" } ],
            "InstanceType" : "t1.micro"
        }
    },
    "AgentLaunchConfig" : { 
        "Type" : "AWS::AutoScaling::LaunchConfiguration",
        "Properties" : {
            "KeyName" : { "Ref" : "keyName" },
            "ImageId" : { "Ref" : "AgentAMI" },
            "UserData" : { "Fn::Base64" : { "Ref" : "AgentUserData" } },
            "SecurityGroups" : [ { "Ref" : "AgentSecurityGroup" }, { "Ref" : "SshSecurityGroup" } ],
            "InstanceType" : "t1.micro"
        }
    },


    "ServerAutoScalingGroup" : {
        "Type" : "AWS::AutoScaling::AutoScalingGroup",
        "Properties" : {
            "AvailabilityZones" : [ { "Ref" : "Zone" } ],
            "LaunchConfigurationName" : { "Ref" : "ServerLaunchConfig" },
            "MinSize" : { "Ref" : "ServerInstanceCount" },
            "MaxSize" : { "Ref" : "ServerInstanceCount" }
        }
    },
    "RelayAutoScalingGroup" : {
        "Type" : "AWS::AutoScaling::AutoScalingGroup",
        "Properties" : {
            "AvailabilityZones" : [ { "Ref" : "Zone" } ],
            "LaunchConfigurationName" : { "Ref" : "RelayLaunchConfig" },
            "MinSize" : { "Ref" : "RelayInstanceCount" },
            "MaxSize" : { "Ref" : "RelayInstanceCount" }
        }
    },
    "AgentAutoScalingGroup" : {
        "Type" : "AWS::AutoScaling::AutoScalingGroup",
        "Properties" : {
            "AvailabilityZones" : [ { "Ref" : "Zone" } ],
            "LaunchConfigurationName" : { "Ref" : "AgentLaunchConfig" },
            "MinSize" : { "Ref" : "AgentInstanceCount" },
            "MaxSize" : { "Ref" : "AgentInstanceCount" }
        }
    },

    "RelaySecurityGroup" : {
        "Type" : "AWS::EC2::SecurityGroup",
        "Properties" : {
            "GroupDescription" : "Enable inbound 20080 and 7916 from Agents",
            "SecurityGroupIngress" : 
            [
                { 
                    "IpProtocol" : "tcp", 
                    "FromPort" : "20080", 
                    "ToPort" : "20080", 
                    "SourceSecurityGroupName" : { "Ref" : "AgentSecurityGroup" } 
                },
                { 
                    "IpProtocol" : "tcp", 
                    "FromPort" : "7916", 
                    "ToPort" : "7916", 
                    "SourceSecurityGroupName" : { "Ref" : "AgentSecurityGroup" } 
                }
            ]
        }
    },
    "ServerSecurityGroup" : {
        "Type" : "AWS::EC2::SecurityGroup",
        "Properties" : {
            "GroupDescription" : "Enable inbound 8080 all and 7918 from Relays",
            "SecurityGroupIngress" : [
                { 
                    "IpProtocol" : "tcp", 
                    "FromPort" : "7918", 
                    "ToPort" : "7918", 
                    "SourceSecurityGroupName" : { "Ref" : "RelaySecurityGroup" } 
                },
                { 
                    "IpProtocol" : "tcp", 
                    "FromPort" : "8080", 
                    "ToPort" : "8080", 
                    "CidrIp" : "0.0.0.0/0" 
                }
            ]
        }
    },
    "AgentSecurityGroup" : {
        "Type" : "AWS::EC2::SecurityGroup",
        "Properties" : {
            "GroupDescription" : "Enable no inbound",
            "SecurityGroupIngress" : []
        }
    },
    "SshSecurityGroup" : {
        "Type" : "AWS::EC2::SecurityGroup",
        "Properties" : {
            "GroupDescription" : "Enable SSH from all",
            "SecurityGroupIngress" : [
                {
                    "IpProtocol" : "tcp",
                    "FromPort" : "22",
                    "ToPort" : "22",
                    "CidrIp" : "0.0.0.0/0"
                }
            ]
        }
    }


},

}