Tool for /etc/hosts update

resolver.rb

require 'resolv'

# Alter /etc/hosts leveraging Augeus
# 1. Find /files/etc/hosts/$x/canonical with needed 
# |
# |---- Found:        2.1 Check ip 
# |
# |---- Not found:    2.2 Create node

node_start    = 1
node_end      = 100
dns_source    = '10.0.10.2'
augtool_cmd   = "augtool -L"


resolv_db                 = {}
resolver                  = Resolv::DNS.new(:nameserver => dns_source)
flag_file_updated         = false


# Make resolvdb
node_start.upto(node_end).each do |num|
  name   = "node-#{num}.domain.tld"
  result = resolver.getaddresses(name)

  unless result.empty?
    node    = resolv_db[name] = {}

    node[:ip]  =  result.first

    IO.popen(augtool_cmd,'r+') do |io|
      io.puts("match /files/etc/hosts/*/canonical[. = '#{name}']")
      io.close_write
      result = io.read
    end
   
    if result =~ /no matches/
      node[:new] = true
    else
      IO.popen(augtool_cmd, 'r+') do |io|
        io.puts("match /files/etc/hosts/*[canonical = '#{name}'][ipaddr = '#{node[:ip]}']")
        io.close_write
        result = io.read
        if result =~ /no matches/
          node[:new] = true
        end
      end
    end
  end
end

IO.popen(augtool_cmd,'r+') do |io|

  # Create new entries
  resolv_db.select { |name, opts| opts[:new] }.each.with_index do |entry,index|
    flag_file_updated = true unless flag_file_updated

    name, opts = entry

    io.puts <<-AUG
      set /files/etc/hosts/0#{index+1}/ipaddr #{opts[:ip]}
      set /files/etc/hosts/0#{index+1}/canonical #{name}
    AUG
  end

  # Update out of sync entries
  resolv_db.select { |name, opts| opts[:dirty] }.each.with_index do |entry,index|
    flag_file_updated = true unless flag_file_updated

    name, opts = entry

    io.puts <<-AUG
      set /files/etc/hosts/*[canonical = '#{name}']/ipaddr #{opts[:ip]}
    AUG
  end
  
  io.puts("save")
  io.close_write
end

if flag_file_updated
  puts "DEBUG: Host file was updated"
else
  puts "DEBUG: Host file is up to date"
end