Monitor looking for changes in IP address. Written in ruby for being cron job.

ip_monitor.rb

#!/usr/bin/env ruby

require 'optparse'
require 'net/http'




options = {
  last_ip_file: "/var/www/last_ip.txt",
  log_file: "/var/www/ip.txt",
  daemon: false
}

OptionParser.new do |opts|
  opts.banner = """Usage: ip_monitor.rb [options]
    Add it to cron job by:

    # crontab -e

    * * * * * ruby ip_monitor.rb
  """

  opts.on("-l", "--log [path]", "Log file path") do |v|
    options[:log_file] = v
  end

  opts.on("-i", "--ip [path]", "Last ip file path") do |v|
    options[:last_ip_file] = v
  end

  opts.on("-d", "--daemon", "Run itself in endless loop") do 
    options[:daemon] = true
  end
end.parse!




def is_valid_ip(ip)
  valid_ip_regex = /^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/
  !!(valid_ip_regex =~ ip)
end

def get_ip_from(addrs)
  uri = URI(addrs)
  ip_addr = Net::HTTP.get(uri).strip
  is_valid_ip(ip_addr) && ip_addr
end

def get_public_ip
  public_ip_providers = ['http://ipinfo.io/ip', 'https://api.ipify.org/', 'https://www.trackip.net/ip']
  public_ip_providers.reduce(false) { |any_ip, url| any_ip || get_ip_from(url) }
end

def monit_ip_change(last_ip_file, log_file)
  my_current_ip = get_public_ip
  my_last_ip = File.exist?(last_ip_file) && File.read(last_ip_file).strip

  if my_current_ip != my_last_ip
    File.write(last_ip_file, my_current_ip)
    File.open(log_file,'a+') { |f| f.write("[#{Time.now}]\tIP change to: #{my_current_ip}\n") }
  end

  puts my_current_ip
end

if options[:daemon]
  sleep(60) && monit_ip_change(options[:last_ip_file], options[:log_file]) until false
else 
  monit_ip_change(options[:last_ip_file], options[:log_file])
end