auto_rds_ip.rb

require "aws-sdk"
require "yaml"
require "sanitize"
require "open-uri"

### 1. set configuration and build a RDS instance ###
config = YAML::load(File.open("#{File.dirname(__FILE__)}/config/config.yml"))
AWS.config({
  :access_key_id => config["access_key_id"],
  :secret_access_key => config["secret_access_key"],
  :max_retries => 3,
  :rds_endpoint => config["end_point"]
})
rds = AWS::RDS.new
puts "==== Checking IP Address at #{Time.now} ===="
### 2. get current ip and check if changed ###
ip_prompt = open("http://checkip.dyndns.org").readline
current_ip = Sanitize.clean(ip_prompt).match(/\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b/).to_s
old_ip = File.open("#{File.dirname(__FILE__)}/old_ip.txt", "r").size > 0 ? File.open("#{File.dirname(__FILE__)}/old_ip.txt", "r").readline.chomp : "192.168.0.1"

if old_ip == current_ip
  abort("==== IP address didn't change, happy coding :) ====")
else
  puts("==== IP address changed, will do the rest for you ====")
  File.open("#{File.dirname(__FILE__)}/old_ip.txt", "w") do |file|  
    file.puts "#{current_ip}"  
  end
end

### 3. check both ip address if already authorized ###
check_flag = false
response = rds.client.describe_db_security_groups(:db_security_group_name => config["security_group_name"])
response[:db_security_groups].first[:ip_ranges].each do |ip_record|
  if ip_record.has_value?("#{current_ip}/32")    
    check_flag = true
    break
  else
    check_flag = false
  end

  if ip_record.has_value?("#{old_ip}/32")
    rds.client.revoke_db_security_group_ingress(:db_security_group_name => config["security_group_name"], :cidrip => "#{old_ip}/32")
  end
end

### 4. authorizing if not in security groups
if check_flag
  puts "==== current ip #{current_ip} was authorized, take a beer and relax ===="
else
  puts "==== current ip #{current_ip} was not authorized, now authorizing for you ===="
  rds.client.authorize_db_security_group_ingress(:db_security_group_name => config["security_group_name"], :cidrip => "#{current_ip}/32")
  puts "==== current ip #{current_ip} authorized, have fun coding :) ===="
end