https://github.com/bazaarvoice/cloudformation-ruby-dsl helpers

helpers.rb

#!/usr/bin/env ruby

require 'bundler/setup'
require 'cloudformation-ruby-dsl/cfntemplate'
require 'cloudformation-ruby-dsl/spotprice'
require 'cloudformation-ruby-dsl/table'

def tags_to_properties(tags)
  tags.map { |k,v| {:Key => k, :Value}}
end

def vpc(name,cidr, enableDnsSupport:nil, enableDnsHostnames:nil, dependsOn:[], tags:{}) 
  properties = {
    :CidrBlock => cidr,
  }
  properties[:EnableDnsSupport] = enableDnsSupport unless enableDnsSupport.nil?
  properties[:EnableDnsHostnames] = enableDnsHostnames unless enableDnsHostnames.nil?
  tags['Name'] = name unless tags.contains?('Name')
  properties[:Tags] = tags_to_properties(tags)
  options = {
    :Type => 'AWS::EC2::VPC',
    :Properties => properties
  }
  options[:DependsOn] = dependsOn unless dependsOn.empty?
  resource name, options
end


def subnet(name,vpc,cidr, availabilityZone:'', dependsOn:[], tags:{})
  properties = {
    :VpcId => vpc,
    :CidrBlock => cidr,
  }
  properties[:AvailabilityZone] = availabilityZone unless availabilityZone.empty?
  tags['Name'] = name unless tags.contains?('Name')
  properties[:Tags] = tags_to_properties(tags)

  options = {
    :Type => 'AWS::EC2::Subnet',
    :Properties => properties
  }
  options[:DependsOn] = dependsOn unless dependsOn.empty?
  resource name, options
end


def security_group(name,description,securityGroupEgress:[], securityGroupIngress:[],dependsOn:[],tags:{})
  properties = {
    :GroupDescription => description
  }
  properties[:SecurityGroupIngress] = securityGroupIngress unless securityGroupIngress.empty?
  properties[:SecurityGroupEgress] = securityGroupEgress unless securityGroupEgress.empty?
  tags['Name'] = name unless tags.contains?('Name')
  properties[:Tags] = tags_to_properties(tags)
  options = {
    :Type => 'AWS::EC2::SecurityGroup',
    :Properties => properties
  }
  options[:DependsOn] = dependsOn unless dependsOn.empty?
  resource name, options
end

def security_group_vpc(name,description,vpc)
  properties = {
    :VpcId => vpc,
    :GroupDescription => description
  }
  properties[:SecurityGroupIngress] = securityGroupIngress unless securityGroupIngress.empty?
  properties[:SecurityGroupEgress] = securityGroupEgress unless securityGroupEgress.empty?
  tags['Name'] = name unless tags.contains?('Name')
  properties[:Tags] = tags_to_properties(tags)
  options = {
    :Type => 'AWS::EC2::SecurityGroup',
    :Properties => properties
  }
  options[:DependsOn] = dependsOn unless dependsOn.empty?
  resource name, options
end

def network_interface(device_index, options:{})
  options[:DeviceIndex] = device_index
  options
end

def instance_vpc(name, image_id, subnet, security_groups, dependsOn:[], properties:{})
  raise "VPC instance #{name} can not contain NetworkInterfaces and subnet or security_groups" if properties.contains(:NetworkInterfaces)
  raise "VPC instance #{name} can not contain non VPC SecurityGroups" if properties.contains(:SecurityGroups)
  properties[:SubnetId] = subnet
  properties[:SecurityGroupIds] = security_groups
  options = {
    :Type => 'AWS::EC2::Instance',
    :Properties => properties
  }
  options[:DependsOn] = dependsOn unless dependsOn.empty?
  resource name, options
end

def instance_with_network(name,image_id,network_interfaces, properties:{})
  raise "VPC instance #{name} can not contain NetworkInterfaces and subnet or security_groups" if properties.contains(:SubnetId) or properties.contains(:SecurityGroups) or properties.contains(:SecurityGroupIds)
  properties[:NetworkInterfaces] = network_interface
  options = {
    :Type => 'AWS::EC2::Instance',
    :Properties => properties
  }
  options[:DependsOn] = dependsOn unless dependsOn.empty?
  resource name, options

end