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Dynamically update Cloudflare DNS records with the machine's current external IP.
#!/usr/bin/env ruby
require 'net/http'
require 'json'
class Cloudflare
def initialize(email, key)
@email = email
@key = key
end
def get(path, query = {})
uri = URI.parse(build_url(path, query))
request = Net::HTTP::Get.new(uri)
perform(uri, request)
end
def put(path, data)
uri = URI.parse(build_url(path))
request = Net::HTTP::Put.new(uri)
request.body = data.to_json
perform(uri, request)
end
private
def build_url(path, query_string = {})
"https://api.cloudflare.com/client/v4#{path}?#{URI.encode_www_form(query_string)}"
end
def perform(uri, request)
request["X-Auth-Email"] = @email
request["X-Auth-Key"] = @key
request["Content-Type"] = "application/json"
Net::HTTP.start(uri.host, uri.port, use_ssl: (uri.scheme == 'https')) do |http|
handle_response http.request(request)
end
end
def handle_response(response)
data = parse_json(response.body)
case response
when Net::HTTPSuccess
data.fetch("result")
else
raise data.fetch("errors").map { |error|
"ERROR #{error["code"]}: #{error["message"]}"
}.join("\n")
end
end
def parse_json(body)
JSON.parse(body)
rescue => error
STDERR.puts "Could not parse JSON response: #{error}"
STDERR.puts body
exit 1
end
end
class VerboseCloudflare
def initialize(cloudflare)
@cloudflare = cloudflare
end
def get(path, query = {})
STDERR.puts "> GET #{path} #{query.to_json}"
verbose_response @cloudflare.get(path, query)
end
def put(path, data)
STDERR.puts "> PUT #{path}"
STDERR.puts "> #{data.to_json}"
verbose_response @cloudflare.put(path, data)
end
private
def verbose_response(response)
JSON.pretty_generate(response).split("\n").each do |line|
STDERR.puts "> #{line}"
end
response
end
end
class DnsUpdater
def initialize(cloudflare, zone_name, record_name)
@cloudflare = cloudflare
@zone_name = zone_name
@record_name = record_name
end
def update_dns_record(new_ip)
@cloudflare.put("/zones/#{zone_id}/dns_records/#{dns_id}", dns_record.merge(content: new_ip))
end
private
attr_reader :zone_name, :record_name
def fetch_zone_id
response = @cloudflare.get("/zones", name: zone_name)
zone = response.first
raise "Could not find zone with name #{zone_name}" unless zone
zone.fetch("id")
end
def zone_id
@zone_id ||= fetch_zone_id
end
def fetch_dns_record
response = @cloudflare.get("/zones/#{zone_id}/dns_records", name: record_name, type: "A")
record = response.first
raise "Could not find \"A\" DNS record with name #{record_name}" unless record
record
end
def dns_record
@dns_record ||= fetch_dns_record
end
def dns_id
dns_record.fetch("id")
end
end
def main(verbose: false)
email = ENV.fetch("CLOUDFLARE_API_EMAIL")
key = ENV.fetch("CLOUDFLARE_API_KEY")
zone_name = ENV.fetch("CLOUDFLARE_ZONE_NAME")
dns_record = ENV.fetch("CLOUDFLARE_DNS_RECORD")
cloudflare = Cloudflare.new(email, key)
cloudflare = VerboseCloudflare.new(cloudflare) if verbose
updater = DnsUpdater.new(cloudflare, zone_name, dns_record)
ip = determine_ip(verbose: verbose)
STDERR.print "Updating... " unless verbose
updater.update_dns_record(ip)
STDERR.puts "OK" unless verbose
STDOUT.puts ip
end
IP_URIS = [
URI.parse("https://4.ifcfg.me/i"),
URI.parse("http://whatismyip.akamai.com/"),
URI.parse("http://checkip.dyndns.com/"),
].freeze
def determine_ip(verbose:)
IP_URIS.each do |uri|
STDERR.puts "> GET #{uri}" if verbose
if (ip = fetch_ip(uri))
return ip
end
end
STDERR.puts "ERROR: Could not determine IP!"
exit 1
end
def fetch_ip(uri)
ip = Net::HTTP.get(uri).strip
if ip =~ /\d{1,3}(\.\d{1,3}){3}/
ip
else
STDERR.puts "ERROR: Not a valid IP: #{ip}"
nil
end
rescue => error
STDERR.puts "ERROR: Could not fetch IP from #{uri}: #{error}"
nil
end
if ARGV.include?("--help")
puts <<-USAGE
#$0 [-v] [--help]
Determines the machine's current external IP, then updates a specific DNS A record on Cloudflare with that IP.
OPTIONS:
-v Verbose. Show all HTTP requests and responses.
--help Show this help.
ENVIRONMENT VARIABLES:
CLOUDFLARE_API_EMAIL (Required) Email address of Cloudflare account.
CLOUDFLARE_API_KEY (Required) API key of Cloudflare account.
CLOUDFLARE_ZONE_NAME (Required) The name of your zone, for example "example.com".
CLOUDFLARE_DNS_RECORD (Required) The DNS record name, for example "example.com"
or "subdomain.example.com". Must be an A record.
USAGE
exit 0
end
main(verbose: ARGV.include?("-v"))
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