manheim/cf_deployer

module CfDeployer
  module Driver
    class Route53
      def initialize(aws_route53 = nil)
        @aws_route53 = aws_route53 || AWS::Route53.new
      end

      def find_alias_target(hosted_zone_name, target_host_name)
        hosted_zone = get_hosted_zone(hosted_zone_name)
        raise ApplicationError.new('Target zone not found!') if hosted_zone.nil?
        record_set = get_record_set(hosted_zone, target_host_name)
        return nil if record_set.nil? || record_set.alias_target.nil?
        remove_trailing_dot(record_set.alias_target[:dns_name])
      end

      def set_alias_target(hosted_zone_name, target_host_name, elb_hosted_zone_id, elb_dnsname)
        Log.info "set alias target --Hosted Zone: #{hosted_zone_name} --Host Name: #{target_host_name} --ELB DNS Name: #{elb_dnsname} --ELB Zone ID: #{elb_hosted_zone_id}"
        hosted_zone_name = trailing_dot(hosted_zone_name)
        target_host_name = trailing_dot(target_host_name)
        hosted_zone = @aws_route53.hosted_zones.find { |z| z.name == hosted_zone_name }
        raise ApplicationError.new('Target zone not found!') if hosted_zone.nil?

        change = {
          action: "UPSERT",
          resource_record_set: {
            name: target_host_name,
            type: "A",
            alias_target: {
              dns_name: elb_dnsname,
              hosted_zone_id: elb_hosted_zone_id,
              evaluate_target_health: false
            }
          }
        }

        batch = {
          hosted_zone_id: hosted_zone.path,
          change_batch: {
            changes: [change]
          }
        }

        CfDeployer::Driver::DryRun.guard "Skipping Route53 DNS update" do
          change_resource_record_sets_with_retry(batch)
        end
      end

      def delete_record_set(hosted_zone_name, target_host_name)
        hosted_zone = get_hosted_zone(hosted_zone_name)
        return unless hosted_zone
        record_set = get_record_set(hosted_zone, target_host_name)
        CfDeployer::Driver::DryRun.guard "Skipping Route53 DNS delete" do
          record_set.delete if record_set
        end
      end
      private

      def change_resource_record_sets_with_retry(batch)
        attempts = 0
        while attempts < 20
          begin
            attempts = attempts + 1
            @aws_route53.client.change_resource_record_sets(batch)
            return
          rescue Exception => e
            Log.info "Failed to update alias target, trying again in 20 seconds."
            sleep(20)
          end
        end

        raise ApplicationError.new('Failed to update Route53 alias target record!')
      end

      def get_hosted_zone(zone_name)
        @aws_route53.hosted_zones.find { |z| z.name == trailing_dot(zone_name.downcase) }
      end
      
      def get_record_set(hosted_zone, target_host_name)
       hosted_zone.resource_record_sets.find { |r| r.name == trailing_dot(target_host_name.downcase) }
      end

      def trailing_dot(text)
        return text if text[-1] == '.'
        "#{text}."
      end

      def remove_trailing_dot(text)
        return text[0..-2] if text && text[-1] == '.'
        text
      end
    end
  end
end