Ruby script to use as a hook for the letsencrypt.sh client

lets-encrypt-route53.rb

#!/usr/bin/env ruby

require 'aws-sdk'

#
# This script requires you to have the following environment variables set:
#   AWS_REGION="us-west-2"
#   AWS_ACCESS_KEY_ID="<YOUR_KEY>"
#   AWS_SECRET_ACCESS_KEY="<YOUR_SECRET_KEY>"
#
# Based on https://gist.github.com/asimihsan/d8d8f0f10bdc85fc6f8a
#

def find_hosted_zone(route53, domain)
  route53 = Aws::Route53::Client.new
  hosted_zones = route53.list_hosted_zones_by_name.hosted_zones

  index = hosted_zones.rindex { |zone| domain.end_with?(zone.name.chop) }
  if index.nil?
    puts 'Unable to find matching zone.'
    exit 1
  end

  hosted_zones[index]
end

def wait_for_change(route53, change_id)
  status = ''
  until status == 'INSYNC'
    resp = route53.get_change(id: change_id)
    status = resp.change_info.status
    if status != 'INSYNC'
      puts 'Waiting for dns change to complete'
      sleep 5
    end
  end
end

def setup_dns(domain, txt_challenge)
  route53 = Aws::Route53::Client.new
  hosted_zone = find_hosted_zone(route53, domain)

  resp = route53.test_dns_answer({
    hosted_zone_id: hosted_zone.id,
    record_name: "_acme-challenge.#{domain}.",
    record_type: "TXT"
  })
  records = []
  resp.record_data.each do |val|
    records << {
      value: val
    }
  end
  records << {
    value: "\"#{txt_challenge}\""
  }
  changes = []
  changes << {
    action: 'UPSERT',
    resource_record_set: {
      name: "_acme-challenge.#{domain}.",
      type: 'TXT',
      ttl: 60,
      resource_records: records.uniq
    }
  }
  resp = route53.change_resource_record_sets(
    hosted_zone_id: hosted_zone.id,
    change_batch: {
      changes: changes
    }
  )
  wait_for_change(route53, resp.change_info.id)
end

def delete_dns(domain, txt_challenge)
  route53 = Aws::Route53::Client.new
  hosted_zone = find_hosted_zone(route53, domain)
  resp = route53.test_dns_answer({
    hosted_zone_id: hosted_zone.id,
    record_name: "_acme-challenge.#{domain}.",
    record_type: "TXT"
  })
  records = []
  method = "DELETE"
  if resp.record_data.count > 1
    method = "UPSERT"
    resp.record_data.delete("\"#{txt_challenge}\"")
    resp.record_data.each do |val|
      records << {
        value: val
      }
    end
  else
    records << {
      value: "\"#{txt_challenge}\""
    }
  end
  changes = []
  changes << {
    action: method,
    resource_record_set: {
      name: "_acme-challenge.#{domain}.",
      type: 'TXT',
      ttl: 60,
      resource_records: records.uniq
    }
  }
  resp = route53.change_resource_record_sets(
    hosted_zone_id: hosted_zone.id,
    change_batch: {
      changes: changes
    }
  )
  wait_for_change(route53, resp.change_info.id)
end

if __FILE__ == $PROGRAM_NAME
  hook_stage = ARGV[0]
  domain = ARGV[1]
  txt_challenge = ARGV[3]

  if hook_stage == 'deploy_challenge'
    puts "stage: #{hook_stage} domain: #{domain} txt_challenge: #{txt_challenge}"
    setup_dns(domain, txt_challenge)
  elsif hook_stage == 'clean_challenge'
    puts "stage: #{hook_stage} domain: #{domain} txt_challenge: #{txt_challenge}"
    delete_dns(domain, txt_challenge)
  end
end