virsh-nat-bridge

#!/usr/bin/env ruby
#
# Copyright 2013 Victor Penso
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

require 'ostruct'
require 'getoptlong' 
require 'erb'
require 'tempfile'
require 'logger'

exec_name = File.split(__FILE__)[-1]
HELP = <<EOF
Usage:

  #{exec_name} [-DhOv] [-b bridge] [-d domain] 
    [-m mac-addresses] [-N network] 
    [-n node[,node,..]] command

Configures and deploys a network configuration for LibVirt
called 'nat_bridge', Lookup of IP- and MAC-addresses for a
given hostname.

Commands:

  li,list 
    List all available FQDNs and IP-addresses (dnsmasq 
    host list format).
  lo,lookup hostname|ip|mac
    Show the configuration for a given MAC-, IP-address
    and hostname.
  st,status
    Show the state of the network.
  start
    Add the configuration to LibVirt and start the network.
  stop
    Stop the network and remove the configuration from 
    LibVirt.

Options:

  -b,--bridge name
    Network bridge used as NAT gateway (default nbr0).
  -d,--debug
    Show stacktraces in case of errors.
  -D,--domain name
    Domain name used for the hosts in the defined
    network (default 'devops.test').
  -h,--help
    Show this help information.
  -m,--mac-addresses prefix
    Mac-address prefix used for the virtual machines
    (default 02:FF:0A:0A:06)
  -N,--network prefix
    IP-address prefix used for the virtual machines
    (default 10.1.1)
  -O,--no-default-nodes
    Don't add the list of default host names to the 
    DNS configuration. Use option -n instead
  -n,--nodes name[,name,...]
    List of host names to added to the DNS.
  --version
    Print program version.
EOF


class System 
  
  def self.exec(command)
    command + ' 2>&1'
    unless $options.command_prefix.nil?
      command = %Q[#{$options.command_prefix} #{command}]
    end
    $logger.debug "Exec [#{command}]"
    # Execute command as subprocess and return the exit code
      pipe = IO.popen(command)
      # Get the process ID from the child
      pid = pipe.pid
      # Read the output from the stream
      output = pipe.read
      # Wait for successful return and pass back the code to the caller
      Process.wait(pid)
      state=$?
      $logger.debug "Returned with #{state}"
      if state == 0
        return output.gsub(/^$\n/, '')
      else
        $logger.warn "Failed to execute [#{command}]"
        return nil
      end
  end


end

module Virsh
  class Network

    def self.config
      # First used IP address in network
      ip = 5 
      # hostname lookup
      hosts = Array.new
      $options.nodes.each do |node|
        hosts << %Q[<host ip="#{$options.network}.#{ip}"><hostname>#{node}</hostname></host>]
        ip += 1
        next if ip > 100
      end
      # resolve IP
      ip = 5
      ips = Array.new
      $options.nodes.each do |node|
        bytes = "%02X" % ip
        mac = "#{$options.mac}:#{bytes}"
        ips << %Q[<host mac="#{mac}" name="#{node}.#{$options.domain}" ip="#{$options.network}.#{ip}"/>]
        ip += 1
        next if ip > 100
      end
      config = ERB.new(<<-EOF
      <network> 
        <name><%= $options.name  %></name>
        <bridge name="<%= $options.bridge %>" />
        <forward mode="nat"/>
        <domain name="<%= $options.domain %>"/>
        <dns>
          <%= hosts.join("\n      ") %>
        </dns>
        <ip address="<%= $options.network %>.1" netmask="<%= $options.netmask %>">
          <dhcp>
            <range start="<%= $options.network %>.100" end="<%= $options.network %>.254" />
            <%= ips.join("\n        ")%>
          </dhcp>
        </ip>
      </network>
      EOF
      ).result(binding)
      return config.gsub(/^  /,'')
    end

    def self.list
      if self.active?
        config = System::exec("virsh net-dumpxml #{$options.name} | grep 'host mac'")
        config.split("\n").each do |line|
          mac,name,ip = line.gsub(/^ *<host mac='/,'').gsub(/' name='/,' ').gsub(/' ip='/,' ').gsub(/' ?\/>/,'').split
          $stdout.puts "#{mac},#{name},#{ip}"
        end
      else
        $stdout.puts "Network [#{$options.name}] not configured."
      end
    end

    def self.lookup(node)
      config = `virsh net-dumpxml #{$options.name} | grep -o '^ *<host mac=.*#{node}.*/>$'`
      if config.empty?
        $stderr.puts "#{node} not defined!"
        exit 1
      end
      mac,name,ip = config.gsub(/^ *<host mac='/,'').gsub(/' name='/,' ').gsub(/' ip='/,' ').gsub(/' ?\/>/,'').split
      $stdout.puts "#{name} #{ip} #{mac}"
    end

    def self.status
      if self.active?
        $stdout.puts System::exec("virsh net-info #{$options.name}")
      else
        $stdout.puts "Network [#{$options.name}] not configured."
      end
    end

    def self.start
      path = "/tmp/libvirt_network.xml.#{Time.now.to_i}"
      File.open(path,'w') do |file|
        file.puts self.config
      end
      System::exec("virsh net-define #{path}")
      System::exec("virsh net-start #{$options.name}")
      System::exec("virsh net-autostart #{$options.name}")
    end

    def self.stop
      System::exec("virsh net-destroy #{$options.name}")
      System::exec("virsh net-undefine #{$options.name}")
    end

    def self.active?
      if System::exec("virsh net-list | grep #{$options.name}").nil?
        false
      else
        true
      end
    end

  end
end


begin

  stdin = $stdin.tty? ? String.new : $stdin.read

  $options = OpenStruct.new
  $options.debug = false
  $options.name = 'nat_bridge'
  $options.bridge = 'nbr0'
  $options.domain = 'devops.test'
  $options.network = '10.1.1'
  $options.netmask = '255.255.255.0'
  $options.mac = '02:FF:0A:0A:06'
  $options.nodes = %w( 
    lxdns01 lxdns02
    lxcm01 lxcm02 
    lxcc01 lxcc02 lxcc03 lxcc04
    lxrm01 lxrm02
    lxb001 lxb002 lxb003 lxb004 lxb005 lxb006 lxb007 lxb008 lxb009 lxb010
    lxmon01 lxmon02 lxmon03 lxmon04 lxmon05
    lxdev01 lxdev02 lxdev03 lxdev04
    lxfs01 lxfs02 lxfs03 lxfs04 lxfs05
    lxhvs01 lxhvs02 lxhvs03 lxhvs04
    lxdb01 lxdb02 lxdb03
    lxrepo01 lxrepo02 lxrepo03
  )
  
  $logger = Logger.new($stderr)
  # Adjust the time format used for the logger
  $logger.datetime_format = "%Y-%m-%d %H:%M:%S "
  $logger.formatter = proc do |severity, datetime, progname, message|
    "[#{datetime.strftime($logger.datetime_format)}] #{severity} -- #{message}\n"
  end
  $logger.level = Logger::FATAL

  nodes = String.new

  GetoptLong.new(
    ['--bridge','-b',GetoptLong::REQUIRED_ARGUMENT],
    ['--domain','-D',GetoptLong::REQUIRED_ARGUMENT],
    ['--debug','-d',GetoptLong::NO_ARGUMENT],
    ['--help','-h',GetoptLong::NO_ARGUMENT],
    ['--log-level','-L',GetoptLong::REQUIRED_ARGUMENT],
    ['--mac-addresses','-m',GetoptLong::REQUIRED_ARGUMENT],
    ['--network','-N',GetoptLong::REQUIRED_ARGUMENT],
    ['--no-default-nodes','-O',GetoptLong::NO_ARGUMENT],
    ['--nodes','-n',GetoptLong::REQUIRED_ARGUMENT],
    ['--version',GetoptLong::NO_ARGUMENT]
  ).each do |opt,arg|
    case opt
    when '--bridge'
      $options.bridge = arg
    when '--debug'
      $options.debug = true
      $logger.level = Logger::DEBUG
    when '--domain'
      $options.domain = arg
    when '--help'
      $stdout.puts HELP
      exit 0
    when '--log-level'
      $logger.level = case arg
      when 'warn'
        Logger::WARN
      when 'debug'
        Logger::DEBUG
      when 'fatal'
        Logger::FATAL
      else
        Logger::INFO
      end
    when '--mac-addresses'
      $options.mac = arg
    when '--network'
      $options.network = arg
    when '--no-default-nodes'
      $options.nodes = Array.new
    when '--nodes'
      nodes = arg
    when '--version'
      $stdout.puts 0.2
      exit 0
    end
  end

  # Add the nodes defined by optional parameters
  nodes.split(',').each do |node|
    $options.nodes << node
  end


  command = ARGV.shift || raise('Expecting command argument!')
  case command
  when 'config'
    $stdout.puts Virsh::Network.config
  when 'status','st'
    Virsh::Network.status
  when 'start'
    Virsh::Network.start
  when 'stop'
    Virsh::Network.stop
  when 'list','li'
    Virsh::Network.list
  when 'lookup','lo'
    node = ARGV.shift || raise('Expecting name argument!')
    Virsh::Network.lookup node
  else
    raise("Command #{command} not supported!")
  end

rescue => exc
  $stderr.puts "ERROR: #{exc.message}"
  $stderr.puts " use -h for detailed instructions"
  if $options.debug
    $stderr.puts '-- Stack Trace --'
    $stderr.puts exc.backtrace
  else
    $stderr.puts 'You may want run this in debug mode with \'-d\''
  end
  exit 1
end

exit 0