[Ruby] Route53 で ELBにサブドメインを振る

前提: Route53 にベースとなるドメインが設定されていること

require "aws-sdk"
AWS.config access_key_id: ENV["AWS_ACCESS_KEY_ID"],
  secret_access_key: ENV["AWS_SECRET_ACCESS_KEY"]

def modify_route53 subdomain, operation, opt = {ttl: 300}
  resp = AWS::Route53.new.client.list_hosted_zones
  resp[:hosted_zones].each do |zone|
    if zone[:name] == "#{ENV['BASE_DOMAIN']}."
      elb_name = ENV["AWS_ELB_DNS_NAME"]
      dns_name = "#{subdomain}.#{zone[:name]}"
      record_type = "CNAME"
      options = {
        ttl: opt[:ttl],
        resource_records: [{value: elb_name}]
      }
      request_params = [dns_name, record_type, options]
      rrsets = AWS::Route53::HostedZone.new(zone[:id]).rrsets
      batch = AWS::Route53::ChangeBatch.new zone[:id]

      case operation
      when :create
        next if rrsets[dns_name, record_type].exists?
        batch << AWS::Route53::CreateRequest.new(*request_params)
      when :delete
        next unless rrsets[dns_name, record_type].exists?
        batch << AWS::Route53::DeleteRequest.new(*request_params)
      else
        raise "Error: Unknown operation."
      end

      batch.call
      break
    end
  end
end

def register_to_route53 subdomain
  modify_route53 subdomain, :create
end

def unregister_from_route53 subdomain
  modify_route53 subdomain, :delete
end

#### test.sh ##########################
# #!/bin/sh
# AWS_ACCESS_KEY_ID=YOUR_ACCESS_KEY_ID \
# AWS_SECRET_ACCESS_KEY=YOUR_SECRET_ACCESS_KEY \
# BASE_DOMAIN=YOUR_BASE_DOMAIN \
# AWS_ELB_DNS_NAME=YOUR_ELB_DNS_NAME \
# ruby -e "require '/path/to/route53.rb'; register_to_route53 'foo'"