cf-custom-resource-template.template

{
  "AWSTemplateFormatVersion" : "2010-09-09",
 
  "Description" : "AWS CloudFormation AMI Look Up Sample Template: Demonstrates how to dynamically specify an AMI ID. This template provisions an EC2 instance with an AMI ID that is based on the instance's type and region. **WARNING** This template creates an Amazon EC2 instance. You will be billed for the AWS resources used if you create a stack from this template.",
 
  "Parameters": {
    "InstanceType" : {
      "Description" : "EC2 instance type",
      "Type" : "String",
      "Default" : "t2.micro",
      "AllowedValues" : ["t2.micro"],
      "ConstraintDescription" : "Must be a valid EC2 instance type."
    }
  },
  "Mappings" : {
    "AWSInstanceType2Arch" : {
      "t2.micro"    : { "Arch" : "HVM64"  }
    }
  },
 
  "Resources" : {
    "EC2Instance": {  
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "InstanceType"   : { "Ref" : "InstanceType" },
        "ImageId": { "Fn::GetAtt": [ "AMIInfo", "Id" ] }
      }
    },
 
    "AMIInfo": {
      "Type": "AWS::CloudFormation::CustomResource",
      "Properties": {
        "ServiceToken": "",
        "Region": { "Ref": "AWS::Region" },
        "Architecture": { "Fn::FindInMap" : [ "AWSInstanceType2Arch", { "Ref" : "InstanceType" }, "Arch" ] }
      }
    }
  },
 
  "Outputs" : {
    "AMIID" : {
      "Description": "The Amazon EC2 instance AMI ID.",
      "Value" : { "Fn::GetAtt": [ "AMIInfo", "Id" ] }
    }
  }  
}