example.cfn

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

    "Description": "Top Secret stack",

    "Parameters": {
        "Name": {
            "Description": "Name of the service",
            "Type": "String"
        },
        "VpcId": {
            "Description": "ID of the VPC onto which to launch the application eg. vpc-1234abcd",
            "Type": "String"
        },
        "PrivateVpcSubnets": {
            "Description": "Subnets to use in VPC for public internet-facing ELB eg. subnet-abcd1234",
            "Type": "CommaDelimitedList"
        },
        "PublicVpcSubnets": {
            "Description": "Subnets to use in VPC for public internet-facing ELB eg. subnet-abcd1234",
            "Type": "CommaDelimitedList"
        },
        "SSLCert": {
            "Description": "ARN of valid SSL certificate",
            "Type": "String"
        },
        "AMI": {
            "Description": "EC2 AMI ID",
            "Type": "String"
        },
        "InstanceType": {
            "Description": "EC2 instance type (m3.large, etc.)",
            "Type": "String"
        },
        "SshKey": {
            "Description": "Key for ssh access to EC2 instances",
            "Type": "String"
        },
        "AlarmSNS": {
            "Description": "ARN for an SNS topic, used to send Cloudwatch alerts for any alarms",
            "Type": "String"
        }
    },

    "Resources": {
        "InstanceProfile": {
            "Type": "AWS::IAM::InstanceProfile",
            "Properties": {
                "Path": "/",
                "Roles": [
                    {
                        "Ref": "Role"
                    }
                ]
            }
        },
        "Role": {
            "Type": "AWS::IAM::Role",
            "Properties": {
                "AssumeRolePolicyDocument": {
                    "Version": "2012-10-17",
                    "Statement": [
                        {
                            "Effect": "Allow",
                            "Principal": {
                                "Service": [
                                    "ec2.amazonaws.com"
                                ]
                            },
                            "Action": [
                                "sts:AssumeRole"
                            ]
                        }
                    ]
                },
                "Path": "/",
                "Policies": [
                    {
                        "PolicyName": "TopSecretPolicy",
                        "PolicyDocument": {
                            "Statement": [
                                {
                                    "Resource": [
                                        { "Ref": "DynamoTable" },
                                        { "Fn::Join": [ "", [ { "Ref": "DynamoTable" },"/index/*"] ] }
                                    ],
                                    "Action": [ "dynamodb:*" ],
                                    "Effect": "Allow"
                                },
                            ]
                        }
                    }
                ]
            }
        },
        "DynamoTable": {
            "Type": "AWS::DynamoDB::Table",
            "Properties": {
                "AttributeDefinitions": [
                    {
                        "AttributeName": "Id",
                        "AttributeType": "S"
                    }
                ],
                "GlobalSecondaryIndexes": [
                    {
                        "IndexName": "my-secondary-index",
                        "Projection": {
                            "ProjectionType": "ALL"
                        },
                        "KeySchema": [
                            {
                                "KeyType": "HASH",
                                "AttributeName": "Id"
                            },
                            {
                                "KeyType": "RANGE",
                                "AttributeName": "LastModified"
                            }
                        ],
                        "ProvisionedThroughput" : {
                            "ReadCapacityUnits" : 1,
                            "WriteCapacityUnits" : 1
                        }
                    }
                ],
                "KeySchema": [
                    {
                        "AttributeName": "Id",
                        "KeyType": "HASH"
                    }
                ],
                "LocalSecondaryIndexes": [ ],
                "ProvisionedThroughput": {
                    "WriteCapacityUnits": 1,
                    "ReadCapacityUnits": 1
                },
                "TableName": { "Ref": "Name" }
            }
            "ElasticLoadBalancer": {
                "Type": "AWS::ElasticLoadBalancing::LoadBalancer",
                "Properties": {
                    "CrossZone": true,
                    "Listeners": [
                        {
                            "Protocol": "HTTPS",
                            "LoadBalancerPort": "443",
                            "InstancePort": "8080",
                            "SSLCertificateId": { "Ref": "SSLCert" }
                        }
                    ],
                    "HealthCheck": {
                        "Target": "HTTP:8080/healthcheck",
                        "Timeout": "10",
                        "Interval": "20",
                        "UnhealthyThreshold": "10",
                        "HealthyThreshold": "2"
                    },
                    "Subnets": {
                        "Ref": "PublicVpcSubnets"
                    },
                    "SecurityGroups": [
                        {
                            "Ref": "ElasticLoadBalancerSecurityGroup"
                        }
                    ]
                }
            },
            "AppServerGroup": {
                "Type": "AWS::AutoScaling::AutoScalingGroup",
                "Properties": {
                    "AvailabilityZones": {
                        "Fn::GetAZs": ""
                    },
                    "VPCZoneIdentifier": {
                        "Ref": "PrivateVpcSubnets"
                    },
                    "LaunchConfigurationName": {
                        "Ref": "LaunchConfig"
                    },
                    "MinSize": 1
                    "MaxSize": 2,
                    "HealthCheckType": "ELB",
                    "HealthCheckGracePeriod": 300,
                    "LoadBalancerNames": [ {"Ref": "ElasticLoadBalancer"}],
                    "Tags": [
                        {
                            "Key": "Name",
                            "Value": {"Ref": "Name"},
                            "PropagateAtLaunch": "true"
                        }
                    ]
                }
            },
            "LaunchConfig": {
                "Type": "AWS::AutoScaling::LaunchConfiguration",
                "Properties": {
                    "ImageId": { "Ref": "AMI" },
                    "SecurityGroups": [ { "Ref": "AppSecurityGroup" } ],
                    "InstanceType": { "Ref": "InstanceType" },
                    "IamInstanceProfile": { "Ref": "InstanceProfile" },
                    "KeyName": { "Ref": "SshKey" },
                    "UserData": {
                        "Fn::Base64": {
                            "Fn::Join": [ "\n", [
                                "#!/bin/bash -v",
                                "# any (bash) commands to execute on instance startup",
                                "# you could also download or execute any other scripts here",
                                "# you might need to dl the code deploy code here (I'm not sure how it works)"
                            ] ]
                        }
                    }
                }
            },
            "ElasticLoadBalancerSecurityGroup": {
                "Type": "AWS::EC2::SecurityGroup",
                "Properties": {
                    "GroupDescription": "Allow public access over HTTP(S)",
                    "VpcId": {
                        "Ref": "VpcId"
                    },
                    "SecurityGroupIngress": [
                        {
                            "IpProtocol": "tcp",
                            "FromPort": "80",
                            "ToPort": "80",
                            "CidrIp": "0.0.0.0/0"
                        },
                        {
                            "IpProtocol": "tcp",
                            "FromPort": "443",
                            "ToPort": "443",
                            "CidrIp": "0.0.0.0/0"
                        }
                    ],
                    "SecurityGroupEgress": [
                        {
                            "IpProtocol": "tcp",
                            "FromPort": "8080",
                            "ToPort": "8080",
                            "CidrIp": "0.0.0.0/0"
                        }
                    ]
                }
            },
            "AppSecurityGroup": {
                "Type": "AWS::EC2::SecurityGroup",
                "Properties": {
                    "GroupDescription": "SSH and HTTP",
                    "VpcId": { "Ref": "VpcId" },
                    "SecurityGroupIngress": [
                        {
                            "IpProtocol": "tcp",
                            "FromPort": "8080",
                            "ToPort": "8080",
                            "SourceSecurityGroupId": {
                                "Ref": "ElasticLoadBalancerSecurityGroup"
                            }
                        },
                        {
                            "IpProtocol": "tcp",
                            "FromPort": "22",
                            "ToPort": "22",
                            "CidrIp": "0.0.0.0/0"
                        }
                    ]
                }
            },
            "HighLatencyAlarmAlert": {
                "Type": "AWS::CloudWatch::Alarm",
                "Properties": {
                    "AlarmName": { "Fn::Join": ["-", [ { "Ref": "Name"}, "alarm", "latency", "alert" ] ]},
                    "AlarmDescription": "Average latency is >= 3s for a 3 minute period",
                    "Namespace": "AWS/ELB",
                    "Dimensions": [ { "Name": "LoadBalancerName", "Value": { "Ref": "ElasticLoadBalancer" } } ],
                    "MetricName": "Latency",
                    "Statistic": "Average",
                    "ComparisonOperator": "GreaterThanOrEqualToThreshold",
                    "Threshold": "3",
                    "Period": "60",
                    "EvaluationPeriods": "3",
                    "AlarmActions": { "Ref": "AlarmSNS" }
                }
            },
            "High5xxAlarmAlert": {
                "Type": "AWS::CloudWatch::Alarm",
                "Properties": {
                    "AlarmName": { "Fn::Join": ["-", [ { "Ref": "Name"}, { "Ref": "Stage" }, "alarm", "5xx", "alert" ] ]},
                    "AlarmDescription": "Number of 5XXs is >= 100 for a 1 minute period",
                    "Namespace": "AWS/ELB",
                    "Dimensions": [ { "Name": "LoadBalancerName", "Value": { "Ref": "ElasticLoadBalancer" } } ],
                    "MetricName": "HTTPCode_Backend_5XX",
                    "Statistic": "Sum",
                    "ComparisonOperator": "GreaterThanOrEqualToThreshold",
                    "Threshold": "100",
                    "Period": "60",
                    "EvaluationPeriods": "1",
                    "AlarmActions": { "Ref": "AlarmSNS" }
                }
            }
        },

        "Outputs": {
            "ElasticLoadBalancer": {
                "Value": { "Fn::GetAtt": [ "ElasticLoadBalancer", "DNSName" ] }
            }
        }
    }
}

• you'll need to add your own attribute definitions to the Dynamo table (you only need to define fields which are used for indexes)
• you'll need to customise a lot of stuff, especially pay attention to the ELB healthcheck - you can set this to the EC2 type initially, but using a HTTP check is recommended

This link will help telling you what properties you can use:

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-template-resource-type-ref.html

Also worth checking out the available functions in cloudformation:

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html

More generally check out the left-hand-side menu bar for useful info.