Certbot hook script for Cloud DNS

clouddns.certbot-hook.rb

#!/usr/bin/env ruby

require 'timeout'
require 'rake'

CLOUD_DNS_ZONE = "..."

def cloud_dns(action, args = [])
  sh "gcloud dns record-sets transaction #{action} --zone=#{CLOUD_DNS_ZONE} #{args.join(" ")}"
end

def load_txt
  `dig +short TXT _acme-challenge.#{ENV['CERTBOT_DOMAIN']}`.chomp
end

cloud_dns "start"
if (old = load_txt()) != ""
  cloud_dns "remove", [
    old,
    "--type=TXT", 
    "--name=_acme-challenge.#{ENV['CERTBOT_DOMAIN']}.",
    "--ttl=1"
  ]
end
cloud_dns "add", [
  ENV['CERTBOT_VALIDATION'], 
  "--type=TXT", 
  "--name=_acme-challenge.#{ENV['CERTBOT_DOMAIN']}.",
  "--ttl=1"
]
cloud_dns "execute"

started_at = Time.now.to_i
while load_txt() != '"' + ENV['CERTBOT_VALIDATION'] + '"'
  if Time.now.to_i - started_at > 60 * 5
    raise Timeout::Error
  end
  sleep 1
end