dynamic-ip.rb

#!/usr/bin/env ruby

require 'date'
require 'net/http'
require 'uri'
require 'json'

# crontab -e
# */30 * * * * path/to/dynamic-ip.rb

IP_REPORT = 'https://_____________'

CLOUDFLARE_API_TOKEN = '________________________________________'

CLOUDFLARE_ZONE_ID = '________________________________'
DNS_RECORD_NAME = '_______________'

DIR = File.expand_path(File.dirname(__FILE__))
STATE_JSON_FILE = File.join(DIR, "dynamic-ip.json")

IP_CHANGE_LOG_FILE = File.join(DIR, "dynamic-ip-changed.log")

time_now = DateTime.now().to_s
puts ":: Time: #{time_now}"

if File.exist?(STATE_JSON_FILE)
  state = JSON.parse(File.read(STATE_JSON_FILE))
else
  state = {}
end

puts ">> getting IP..."

ip = Net::HTTP.get(URI(IP_REPORT)).strip
puts ":: IP: #{ip}"

if state["last_ip"] == ip
  puts ":: IP is the same, skipping..."
  exit 0
end

puts ">> getting record id of #{DNS_RECORD_NAME}..."

record_list_uri = URI("https://api.cloudflare.com/client/v4/zones/#{CLOUDFLARE_ZONE_ID}/dns_records?name=#{DNS_RECORD_NAME}")
dns_record_id = Net::HTTP.start(record_list_uri.hostname, record_list_uri.port, use_ssl: true) do |http|
  req = Net::HTTP::Get.new(record_list_uri)
  req["Content-Type"] = "application/json"
  req["Authorization"] = "Bearer #{CLOUDFLARE_API_TOKEN}"

  JSON.parse(http.request(req).body)["result"][0]["id"] rescue nil
end

if dns_record_id
  puts ":: dns_record_id: #{dns_record_id}"
else
  puts ":: can not get dns_record_id, exiting..."
  exit 1
end

puts ">> updating IP to cloudflare..."
patch_ip_uri = URI("https://api.cloudflare.com/client/v4/zones/#{CLOUDFLARE_ZONE_ID}/dns_records/#{dns_record_id}")

res = Net::HTTP.start(patch_ip_uri.hostname, patch_ip_uri.port, use_ssl: true) do |http|
  req = Net::HTTP::Patch.new(patch_ip_uri)
  req["Content-Type"] = "application/json"
  req["Authorization"] = "Bearer #{CLOUDFLARE_API_TOKEN}"
  req.body = {
    "type" => "A",
    "content" => ip,
  }.to_json

  http.request(req)
end

puts ':: req sent, result:'
pp res
pp res.body

state["last_ip"] = ip

puts ">> writing state to file..."
File.write(STATE_JSON_FILE, state.to_json)
puts ':: state file written'

puts ">> writing IP_CHANGE_LOG_FILE: #{IP_CHANGE_LOG_FILE}"
ip_change_log = File.open(IP_CHANGE_LOG_FILE, 'a')
ip_change_log.write("#{time_now} :: #{ip}\n")
ip_change_log.close
puts ':: state file written'